Young-Soo Kim

ABSTRACT This paper describes designing a tip-tilt-piston motion controller of fast steering mirror(FSM) in the Giant Magellan telescope(GMT) as a preliminary study. The mathematical model of tip-tilt-piston motion system of FSM is derived by using second-order differential equation approximation, which the overall model is considered as Multi-Input Multi-Output(MIMO) system. Based on this model, a H∞ controller is designed with mixed sensitivity approach. It's solved by two Riccati equations through selecting the appropriate weighting functions.

ABSTRACT In this paper, the decentralized iterative learning control algorithm for heterogeneous systems with interconnections on the arbitrary manner is presented. By synthesizing the ILC update law in each subsystem, the reference trajectory tracking can be achieved perfectively. For the validity of the proposed ILC algorithm, the numerical example is given.

ABSTRACT In this paper, iterative learning control for the trajectory tracking problem of heterogeneous systems interconnected arbitrarily is presented. The existing interconnected system is remodeled as a 1D system including all the subsystems, and then ILC scheme is designed and analyzed by using the discrete-time linear repetitive process (DLRP) which is based on the 2D system theory. The iterative control law used in this paper has the feedback loop of both the state error and tracking error. An illustrative example is given for the validity of the proposed control scheme.

In addition to the frontal lobe, the temporal lobe may also be involved in typical absence seizures. However, few studies have addressed the relationship between this involvement and drug responsiveness in childhood absence epilepsy (CAE). In this study, we observed the current-source distribution (CSD) of generalized spike-and-wave discharges (GSWDs) and investigated the relationship between temporal lobe involvement in the CSD and responsiveness to initial antiepileptic drug (AED) in CAE. Seventeen consecutive patients with CAE were retrospectively enrolled in the study. Patients were divided into an initial-response group and an initial-failure group, according to their responsiveness to the initial AED treatment. For each patient, the spike peak CSD of an averaged GSWD was obtained from the initial electroencephalogram. We compared the incidence of temporal involvement in the CSD between the two groups. We also compared clinical variables, including age of onset, gender, type and dose of first AED, time to cessation of clinical seizures, and seizure-free status. The initial-response and initial-failure groups contained 12 and five patients, respectively. Temporal lobe involvement was more frequent (80% vs. 17%, p=0.03), and time to cessation of clinical seizures was more prolonged (median 2.5 months vs. 8 months, p<0.01) in the initial-failure than in the initial-response group. None of the other variables studied differed between groups. Initial AED failure was associated with temporal involvement in the CSD of CAE patients. This electrophysiological information may be helpful in clinical practice by estimating the efficacy of initial AED treatment in AED-naïve CAE patients in advance.

In order to investigate functional characterization of callus extracts of apple 'Hirosaki' for cosmetic materials, biological activities of its extracts including wrinkle improvement, hair growth, and anti-inflammatory effect were investigated. The callus extract showed similar activity with TGF- used as positive control at 50 in the test of collagen synthesis, and increased 40% of proliferation of hair follicle dermal papilla cells. Especially, in case of anti-inflammatory effect, callus extract inhibited about 50% of COX-2 expression which was known as response for intermediating inflammation, and about 70% of eotaxin-1 production which was increased by atopy dermatitis.

Synthetic Aperture Radar (SAR) has been used for mapping the surface geomorphol-ogy of cloudy planets like Venus as well as the Earth. The cloud-free Mars is also going to be scanned by SAR in order to detect buried water channels and other fea-tures under the very shallow subsurface of the ground. According to the 'Mid and Long-term National Space Development Plan' of Korea, SAR satellites, in addition to the EO (Electro-Optical) satellites, are supposed to be developed in the frame of the KOMPSAT (Korean Multi-Purpose Satellite) program. Feasibility of utilizing a SAR payload on KOMPSAT platform has been studied by KARI in collaboration with As-trium U.K. The purpose of the SAR program is Scientific and Civil applications on the Earth. The study showed that KOMPSAT-2 platform can accommodate a small SAR like Astrium's MicroSAR. In this paper, system aspects of the satellite design are pre-sented, such as mission scenario, operation concept, and capabilities. The spacec...

Giant Magellan Telescope possesses two secondary mirror systems - Fast Steering Mirror (FSM) and Adaptive Secondary Mirror (ASM). FSM would compensate wind effect and structure jitter by using a tip-tilt mechanism. FSM is 3.2 m in diameter and has a fast focal ratio of 0.65. FSM consists of seven segments each of which is 1.1 m in diameter. An FSM prototype (FSMP) has been developed, which consists of a full-size off-axis mirror segment and a tip-tilt test-bed. By developing the FSMP, the key technologies- fabrication of highly aspheric off-axis mirror and tip-tilt actuation - would be achieved. The backside of the mirror was completed by spherical surface with light-weighting and etching. The grinding of the front surface was finished, and polishing is in progress. The tip-tilt test-bed has also been manufactured and assembled. Frequency tests are being performed with fine tuning of the assembly. For the development of the FSMP, Korea Astronomy and Space Science Institute is workin...

Changing patterns of the reemerging Plasmodium vivax malaria in the Republic of Korea (South Korea) during the period 1993 to 2005 are briefly analyzed with emphasis on the control measures used and the effects of meteorological and entomological factors. Data were obtained from the Communicable Diseases Monthly Reports published by the Korea Center for Disease Control and Prevention, and webpages of World Health Organization and United Nations. Meteorological data of Kangwon-do (Province) were obtained from local weather stations. After its first reemergence in 1993, the prevalence of malaria increased exponentially, peaking in 2000, and then decreased. In total, 21,419 cases were reported between 1993 and 2005 in South Korea. In North Korea, a total of 916,225 cases were reported between 1999 and 2004. The occurrence of malaria in high risk areas of South Korea was significantly (P > 0.05) correlated with the mosquito population but not with temperature and rainfall. Control pr...

To determine whether clinical features of rotavirus-associated seizures have been altered by rotavirus vaccination, we compared clinical and laboratory data of 2 groups of patients with rotavirus-associated seizures: pre- and post-vaccine introduction groups. The seizure characteristics differed significantly between the groups, with a lower incidence of fever at seizure onset, longer interval between the onset of gastroenteritis and seizures, and more frequent seizures in the postintroduction group. These characteristics may suggest that seizure susceptibility was increased in the postintroduction group. Based on the lower serum Cl(-) (102.1 ± 4.1 vs 98.2 ± 3.2 mg/dL; P < .01) and Ca(2+) levels (9.2 ± 0.4 vs 9.0 ± 0.3 mg/dL; P = .12) in the postintroduction group, we propose that a change in the subjects' susceptibility to the rotavirus enterotoxin may have played a role in increasing the seizure susceptibility in this group. Our results suggest that a rotavirus vaccination ...

A full-scale pilot plant using SBR process was experimented with an actual wastewater emanating from a recreational center. The main purpose of this investigation was to evaluate applicability in the field and process removal efficiencies in terms of BOD, SS, TN and TP and its ...

Camellia japonica oil (CJ oil) has been used traditionally in East Asia to nourish and soothe the skin as well as help restore the elasticity of skin. CJ oil has also been used on all types of bleeding instances. However, little is known about its anti-inflammatory effects. Therefore, the anti-inflammatory effects of CJ oil and its mechanisms of action were investigated. CJ oil inhibited LPS-induced production of NO, PGE(2), and TNF-α in RAW264.7 cells. In addition, expression of COX-2 and iNOS genes was reduced. To evaluate the mechanism of the anti-inflammatory activity of CJ oil, LPS-induced activation of AP-1 and NF-κB promoters was found to be significantly reduced by CJ oil. LPS-induced phosphorylation of IκBα, ERK, p38, and JNK was also attenuated. Our results indicate that CJ oil exerts anti-inflammatory effects by downregulating the expression of iNOS and COX-2 genes through inhibition of NF-κB and AP-1 signaling. [BMB reports 2012; 45(3): 177-182].

To report a consecutive series of neonates with seizures or apnea and displaying white matter injuries with distinctive magnetic resonance diffusion-weighted imaging (DWI) pattern, and to discuss the high positive rate of rotavirus infection seen in these patients. In a retrospective review of neonates who were admitted to a tertiary referral center with seizures or apnea, we found a distinctive pattern of white matter injury (symmetrical restricted diffusion in the periventricular white matter and white matter tracts including the corpus callosum) in 18 patients. We describe the clinical and laboratory features of these 18 neonates. Additional PCR analyses for rotaviruses and parechoviruses were performed on banked frozen samples of CSF of 4 patients and blood of 15 patients. All 18 patients were born at term and healthy until symptoms occurred 4-7 days after birth. No history of asphyxia was observed. Only 1 patient presented with fever, and no patient showed a rash. All patients ...

General anesthetic-induced coma therapy has been recommended for the treatment of refractory status epilepticus (RSE). However, the influence of electroencephalographic (EEG) burst suppression (BS) on outcomes still remains unclear. This study investigated the impact of intravenous anesthetic-induced BS on the prognosis of RSE using a retrospective analysis of all consecutive adult patients who received intravenous anesthetic treatment for RSE at the Seoul National University Hospital between January 2006 and June 2011. Twenty-two of the 111 episodes of RSE were enrolled in this study. Of the 22 RSE patients, 12 (54.5%) were women and 18 (81.4%) exhibited generalized convulsive status epilepticus. Sixteen patients (72.7%) were classified as having acute symptomatic etiology, including three patients with anoxic encephalopathy, and others with remote symptomatic etiology. Only two patients (9.1%) had a favorable Status Epilepticus Severity Score (0-2) at admission. All patients recei...

ABSTRACT This paper develops a tip-tilt motion controller of fast steering mirror (FSM) in the Giant Magellan telescope (GMT). A mathematical model of tip-tilt motion system of FSM is derived, and then based on this model, stability analysis is carried out. A heuristic adaptive controller is designed for the tip-tilt motion control with modeling error. The heuristic controller consists of two different adaptations such as initial adaptive control and adaptation at steady state errors . Through numerical simulations, the validity of the controller is illustrated. After that this paper addresses several practical issues like disturbance from wind, actuator saturation and resonance frequency from mechanical structure in implementing the controller to the actual system.

ABSTRACT Iterative learning control (ILC) has been successfully employed for trajectory tracking of uncertain dynamic systems with less system information. This paper attempts to adopt the benefits of ILC to improve the trajectory tracking performance of spatially interconnected systems. By utilizing the ILC update law along the iteration domain repetitively, a perfect reference trajectory tracking can be ensured. It is the key benefit of using ILC that less system model information is used in the design of a trajectory tracking controller for spatially interconnected systems. Through a numerical simulation, the validity of the proposed control scheme is illustrated.

ABSTRACT The fast steering mirror (FSM) is a key element in astronomical telescopes to provide real-time angular correction of line-of-sight error due to telescope jitter and wind-induced disturbance. The Giant Magellan Telescope (GMT) will utilize a FSM as secondary mirror under unfavorable wind conditions that excites the telescope at the lowest resonance frequency around 8Hz. A flexure in the center of the mirror constrains lateral displacements, while still allowing tip-tilt motion to steer. Proper design of this central flexure is challenging to meet lateral loading capability as well as angular and axial flexibility to minimize optical surface distortion forced by redundant constraints at the flexure. We have designed the lateral flexure and estimated its performance from a variety of design case studies in a finite element analysis tool. A carefully designed finite element model at the sub-system level including the flexure, lightweight mirror and 3 point axial supports allows evaluating whether the designed flexure is qualified within specifications. In addition, distorted surface maps can be achieved as a function of forces that could be induced in telescope operation or due to misalignment errors during assembling. We have also built a test set-up to validate the finite element analysis results. Optical quality was measured by a phase shifting interferometer in various loading conditions and the measurements were decomposed by standard Zernike polynomials to concentrate specific surface shapes and to exclude low order shapes as measurement uncertainties.

ABSTRACT The Giant Magellan Telescope (GMT) will be one of the next class of extremely large segmented mirror telescopes. The GMT will utilize two Gregorian secondary mirrors, and Adaptive Secondary Mirror (ASM) and a Fast-steering Secondary Mirror (FSM). The FSM consists of six off-axis mirrors surrounding a central on-axis circular segment. The segments are 1.1 m in diameter and conjugated 1:1 to the seven 8.4 m segments of the primary. A prototype of the FSM mirror (FSMP) has been developed, analyzed and tested in order to demonstrate the mechanical and optical responses of the mirror assembly when subjected to structural and thermal loadings. In this paper, the mechanical and thermal performances of the FSMP were evaluated by performing finite element analyses (FEA) in NX Nastran. The deformation of the mirror's lateral flexure was measured when the FSMP was axially loaded and the temperature response of the mirror assembly was measured when exposed to a sample thermal environment. In order to validate the mirror/lateral flexure design concept, the mechanical, optical and thermal measurements obtained from the tests conducted on mirrors having two different lateral flexures were compared to the responses calculated by FEA.

We conducted this study to define the relationship between the hyperventilation-induced EEG changes (HV-EEG changes) and PCO2. In consecutive EEG recordings of 190 patients, we gathered data on PCO2 during the hyperventilation procedure. The data included baseline PCO2 (B-PCO2), PCO2 after 5 min of hyperventilation (5 min-PCO2), the mean value of the PCO2 (M-PCO2), and the difference between B-PCO2 and 5 min-PCO2 (ΔPCO2). We divided the enrolled patients into two groups by hyperventilation response (response group and no-response group), presence of epilepsy (epileptic group and non-epileptic group) and age (child-adolescent group and adult group) repeatedly. We compared the four variables between the two groups in each pair. ΔPCO2 was 14.2±5.0 mmHg (mean±SD) in response group (n=48) and 12.4±5.0 in no-response group (n=142; p=0.033) for all the patients. For adult patients only, 5 min-PCO2 was 24.3±3.4 in response group (n=30) and 26.2±4.6 in no-response group (n=115; p=0.048), and ΔPCO2 was 15.8±4.0 and 12.9±5.0, respectively (p=0.004). In non-epileptic patients, 5min-PCO2 was 23.4±2.2 in response group (n=7) and 26.3±3.8 in no-response group (n=44; p=0.026), and ΔPCO2 was 15.9±4.3 and 12.7±3.9, respectively (p=0.053). In adults and non-epileptic patients, ΔPCO2 and 5 min-PCO2 may be crucial to the induction of EEG changes by hyperventilation. PCO2 could be a crucial factor for provoking HV-EEG changes in a limited group of patients.

ABSTRACT Fast Steering Mirror (FSM) is one of the secondary mirror systems of the Giant Magellan Telescope. FSM is 3.2 m in diameter and has a fast focal ratio of 0.65. FSM consists of seven segments. Each segment is 1m in diameter and the surrounding six segments except the center one are off-axis mirrors. FSM compensates image degradations caused by wind disturbances and structure jitter by using a tip-tilt mechanism. Korea Astronomy and Space Science Institute is developing a prototype of the FSM together with collaborators in Korea and USA. The prototype is a full-size FSM segment, which has two features; an off-axis mirror and a test-bed for tip-tilt actuation. The off-axis mirror with a diameter of 1.06m is being fabricated. Light-weighting is proceeding, and polishing, figuring, and testing will follow. The tip-tilt test-bed is integrated with a dummy aluminum mirror, three axial supports, a lateral support, and a test-bed frame. The test-bed will demonstrate to verify the tip-tilt parameters and measure reaction forces from tip-tilt actuation. The prototype is expected to be completed by 2012. In this paper, we present progress of the prototype development, and future works.

Although non-convulsive status epilepticus (NCSE) is an important type of epilepsy, it is not often recognized. In order to analyze the clinical characteristics and outcome in patients with NCSE, we examined the medical records of patients with NCSE admitted to the Seoul National University Hospital between June 2005 and October 2008. The clinical details and electroencephalography records of 34 adult NCSE patients (aged over 16 years) were collected. Their mean age was 47 years (standard deviation 20 years, range, 16-87 years), and 20 were female. Twenty-seven patients (79.4%) showed decreased awareness with acute onset, and seven (20.6%) were obtunded or comatose. Ten patients (29.4%) had a history of epilepsy, and four (11.8%) had a history of stroke. NCSE was etiologically attributed to acute medical or neurological problems in 25 patients (73.5%), was cryptogenic in three (8.8%), and was secondary to underlying epilepsy in six (17.7%). Acute symptomatic etiology was associated with poor recovery (p=0.048), with all unresponsive patients in this acute symptomatic group. Eight (23.5%) of the 34 NCSE patients did not recover or died, whereas nine (26.5%) recovered. Our study shows that the presence of acute symptoms or central nervous system infection is associated with poor outcome, suggesting that a high level of vigilance is required to identify and prevent complications.

... ScL 40, 63--69. McCarthy JF, Jimenez BD and Barbee T. (1985) Effect of dissolved humic material on accumulation of polycyclic aromatic hydrocarbons: structure-activity relationships. Aquat. ... Butterworths, Boston. Thurman ME (1985) Organic Geochemistry of Natural Waters. ...

ABSTRACT In this paper, robust stability analysis of spatially interconnected systems with random delays as well as structured uncertainties in discrete-time domain is presented. The random delays are represented as a series of Markovian jumping parameters with some transition probability. A sufficient condition to guarantee well-posedness, stochastic stability, and H∞H∞ performance of the spatially interconnected systems is established. Through numerical simulations, the validity of the proposed approach is illustrated.

Aluminum–titanium mixed metal oxides with various compositions were synthesized by sol–gel method and the photocatalytic activities for acetaldehyde decomposition were investigated. A mixture of aluminum isopropoxide and titanium butoxide in isopropanol ...

The solubility of sodium naproxen was determined over a range of temperatures from 15.2 degrees C to 39.7 degrees C by two methods: analyses of samples from equilibrated solutions and a recently developed procedure utilizing a focused-beam reflectance method (FBRM). The results demonstrate the utility of the newer and, in some cases, simpler method. A discontinuity in the solubility was observed at 29.8 degrees C, identifying the temperature as which the dihydrate and anhydrous forms of sodium naproxen trade places as being the more stable of the two forms. The heats of solution for the two pseudopolymorphs were obtained from van't Hoff plots of the solubility data. These results were used to demonstrate how the heat of solution of one form can be estimated using the heat of dehydration obtained from differential scanning calorimetry (DSC) and the heat of solution from another form.

Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.