태화강의 수질오염 특성에 관한 연구 : 화학적 산소요구량과 염소이온 농도 Chemical Oxygen Demand and Chloride Ion

류석환 한국환경과학회 1993 한국환경과학회지 Vol.2 No.4

The COD values and chloride ion concentrations of the Taewha river flowing through Ulsan area were determined along the main stream and the relationships between CODs and chloride ion concentrations were described. The results showed that the middle-upper stream and downstream of the Taewha river were polluted deeply with municipal sewage and self-purification occured in the middle-downstream of the river. When domestic sewage is a main source of pollutants, and is especially the only source of chloride in the stream water, the ratio of COD/[Cl^-] will be utilizable as a measure of self-purification of the stream.

대구가톨릭대학병원에서 자문의뢰 의사의 정신과 자문의뢰 만족도와 정신과에 대한 인식과 태도

류석환,이양현 대한신경정신의학회 2002 신경정신의학 Vol.41 No.6

잔존충전용량 추정을 위한 퍼지 H∞ 필터 설계

류석환,오설동 한국지능시스템학회 2010 한국지능시스템학회논문지 Vol.20 No.2

This paper deals with a nonlinear fuzzy H∞ filter design for SOC(state of charge) estimation in Lithium polymer battery. The dynamic equation of the battery cell is modeled as a T-S fuzzy system and the filter is designed via solutions of linear matrix inequalities. In order to illustrate the performance of the designed filter, a computer simulation is performed using the experimental data with the UDDS(urban dynamometer driving schedule) current profile. 본 논문은 리튬폴리머 배터리의 잔존충전용량 추정을 위한 비선형 퍼지 H∞ 필터의 설계 방법을 제시한다. 배터리 셀의 동적방정식을 T-S 퍼지시스템으로 모델하고 선형행렬 부등식의 해를 이용하여 퍼지필터를 설계한다. 제시한 퍼지 H∞ 필터의 성능을 입증하기 위하여 UDDS 전류 프로파일을 사용한 실험 데이터를 이용하여 모의실험을 수행하였다.

의과대학 학생의 자살 사고와 우울증, 삶의 질

류석환 순천향대학교 의학연구소 2009 Journal of Soonchunhyang Medical Science Vol.14 No.3

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열간압연 Monitor AGC에의 H∞ 최적화 기법의 적용

류석환 대구대학교 산업기술연구소 1992 産業技術硏究 Vol.11 No.-

A robust monitor AGC(Automatic Gauge Control) system for a hot strip mill plant of POSCO is designed by minimizing the H∞ norm of a so called mixed sensitivity function. In order to solve the minimization problem, the polynomial approach proposed by kwakernaak[5] is used. The controller performance is tested by a computer simulation under various circumstances.

A Balanced Model Reduction for Fuzzy Systems with Time Varying Delay

류석환,최병재 한국지능시스템학회 2004 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.4 No.1

This paper deals with a balanced model reduction for T-S(Takagi-Sugeno) fuzzy systems with time varying state delay. We define a generalized controllability gramian and a generalized observability gramian for a stable T-S fuzzy delayed systems. We obtain a balanced state space realization using the generalized controllability and observability gramian and obtain a reduced model by truncating states from the balanced state space realization. We also present an upper bound of the approximation error. The generalized controllability gramian and observability gramian can be computed from solutions of linear matrix inequalities. We demonstrate the efficacy of the suggested method by illustrating a numerical example.

특이섭동 퍼지시스템의 H∞ 출력 궤환제어

류석환,최병재 한국지능시스템학회 2004 한국지능시스템학회논문지 Vol.14 No.3

This paper deals with an H∞ output feedback controller design for singularly perturbed T-S fuzzy systems. It is shown that the H∞ norm of the singularly perturbed T-S fuzzy system is less than γ for a sufficiently small ε>0 if the H∞ norms of both the slow and fast subsystem are less than γ. Using this fact, we develop a linear matrix inequality based design method which is independent of the singular perturbation parameter ε. A numerical example is provided to demonstrate the efficacy of the proposed design method. 이 논문에서는 특이섭동 T-S 퍼지시스템의 H∞ 출력 궤환 제어기의 설계를 취급한다. 특이섭동 시스템에서 저속 부시스템과 고속 부시스템의 H∞ 노옴이 각각 γ보다 적다면 충분히 적은 ε>0에 대해서 특이섭동 퍼지시스템의 H∞ 노옴이 γ보다 적음을 증명한다. 이러한 사실을 이용하여 특이섭동 파라메터 ε과 무관한 선형 행렬부등식을 기반으로하는 제어기 설계법을 제시한다. 제시된 설계법의 효용성을 입증하기 위하여 수치예를 보여준다.

독시사이클린이 저산소 조건에서 세포 생존에 미치는 영향

류석환,서헌석,신임희,임선하,이종원 대한신경정신의학회 2002 신경정신의학 Vol.41 No.5

연구목적: 뇌졸중은 환자의 삶에 심각한 영향을 주는 질환이나, 현재까지의 치료법은 수 시간이내에 병원에 도착 해야 양호한 결과를 기대할 수 있는 단점이 있다. 이 시간동안 세포를 살려두기 위한 새로운 방법을 찾 고자 하였다. 방 법: 쥐의 신경교종세포주를 사용하여 정상포도당 상태와 고포도당 상태에서 독시사이클린이 세포의 생존에 미치는 영향을 알아보기 위하여 hemocytometer를 이용하여 생존한 세포의 수를 구하고, 포도당 및 젖 산 농도와 pH를 측정하였다. 결 과: 정상포도당 배지에서 독시사이클린이 투여되지 않은 대조군에서는 저산소 조건(1% 산소농도)에서 배양 1일 후 배지 내의 포도당이 모두 고갈되어 세포가 모두 죽었으나 독시사이클린이 투여된 경우에 는 포도당이 모두 고갈되었음에도 불구하고 세포의 생존이 현저하게 개선되었다. DNA 조각내기 아쎄이 검사에서 세포 자살을 억제하여 세포 생존을 개선시켰다. 고포도당 배지에서는 독시사이클린이 투여 되지 않은 대조군에서는 저산소 조건에서 약 60시간이 지난 후에 포도당은 남아 있으나 pH가 감소하여 세포들이 모두 죽는데 반해, 독시사이클린이 투여된 경우에는 포도당은 남아 있으나 pH 감소가 억제 되어 70시간 후에도 세포가 살아있었다 결 론: 독시사이클린이 저산소 조건에서 정상포도당 농도와 고포도당 농도 모두에서 직접적으로 세포의 생존 을 개선시켰으며, 이러한 결과는 허혈성 뇌졸중의 치료에 응용될 가능성이 있음을 시사한다. Objectives:Cerebrovascular diseases seriously effect patient’s quality of life, and the treatment has, its limitation to bring functional recovery unless a patient is brought to a hospital within several hours from the onset. In this study, we tried to find a way to prolong the survival cells under hypoxic conditions using cell culture. Methods:Cultured rat glioma cells grew in normal and high glucose medium under hypoxic conditions, with or without doxycycline. Cell viability, glucose and lactic acid concentration were measured. Results:The cells died after 1 day of culture under hypoxic conditions in normal glucose medium without doxycycline due to the total consumption of glucose. On the contrary, the cells still survived even after 3 days of culture under the same hypoxic conditions in normal glucose medium with doxycycline despite the total consumption of all glucose. For both cases, the cause of death was not, at least, due to the decrease of pH as the pH was kept neutral during the whole period of culture. In this case, doxycycline was the cell survival factor by suppressing apoptosis, which was proved by DNA fragmentation assay. On the other hand, the cells died after 60 hours of culture under hypoxic conditions in high glucose medium without doxycycline due to the decrease of pH. The cells still survived even after 70 hours of culture under the same hypoxic conditions in high glucose medium with doxycycline due to the inhibition of decreased pH. For both cases, the cause of death was not, at least, due to the consumption of total glucose because some glucose remained in the medium at the end culture. Conclusion:Doxycycline increased cell viability both in normal glucose and high glucose medium under hypoxic conditions, which might have an application for the treatment of patients with ischemic stroke.

비정신과 의사의 정신과에 대한 인식과 태도

류석환,이양현 대한생물치료정신의학회 2001 생물치료정신의학 Vol.7 No.1

Objectives : The aim of this study was to investigate the nonpsychiatric physicians' attitudes and opinions toward psychiatry. Methods : A total of 212 survey questionnaire was distributed to physicians in Daegu Catholic University Medical Center. 181 surveys were returned. The return rate was 85.4%. All answers were analyzed statistically by ANOVA or t -test Results : Internal consistency was high, measuring 0.719 for the 26 items. In factor overall merits of the field of psychiatry, for positions, staffs scored more higher than residents averagely, and for age, those who are forties scored highest, those who are twenties lowest In factor efficacy, for positions, staffs scored more higher than residents and interns averagely, and for age, those who are above fifties scored highest, those who are twenties lowest. In factor role definition and functioning of psychiatrists and in factor possible abuses and social criticisms, there was no significant difference in sex, position, and specialty. In factor career and personal rewards, for positions, staffs scored more higher than residents and interns averagely, and for age, those who are forties scored highest, those who are twenties lowest. Elderly physicians and more clinical experienced physicians were likely to be positive toward psychiatry. There was no statistically difference in sex, among medical group and surgical group and support group. Conclusion : This study results support the hypothesis that elderly physicians and experienced physicians have more positive attitude toward psychiatry than younger and less experienced physicians, and no significant difference In sex.

일 병원 직원의 삶의 질에 관한 예비적 연구 - 경험에 대한 비교 -

류석환,서승우,정수기,Ryu, Seuk-Hwan,Seo, Seung-Woo,Jung, Soo-Gie 한국정신신체의학회 2004 정신신체의학 Vol.12 No.1

연구목적: 병원에 근무하는 직원의 삶의 질에 관하여 조사하여 향후, 정신과 환자와 보호자의 삶의 질을 평가하기 위한 기초자료로 활용하기 위함이다. 방 법: 안강중앙병원에 근무 중인 직원을 대상으로 하여 삶의 질에 관한 설문지를 이용하여 조사하였다. 결 과: 삶의 질은 통계적으로 유의하지 않으나 대체로 긍정적이었으며, 간접 접촉군이 더 긍정적이었다. 기혼집단이 더 긍정적이었다. 연령에서는 30대와 40대가 더 긍정적이었으며, 대체로 고학력군이 긍정적이었으나, 유능감 요인과 신체적 안녕 요인은 저학력군이 더 긍정적이었다. 결 론: 본 연구에서 실시된 장기 가족교육모형은 가족의 대처방식을 향상시키고 우울증상의 감소를 가져오며, 환자가 자각하는 가족의 정서적 지지의 향상 및 우울증상의 호전을 가져오고, 재입원율의 저하 및 사회재활의 향상을 보이는 것으로 나타났다. Objectives: The aim of this study was to investigate the quality of life of staffs in a hospital. The results of the investigation were taken as a basic data of evaluating the quality of life of patients in psychiatric hospital and family members. Methods: The subjects of this study were Ankang Chungang Hospital staffs. The tool of this study was the Korean version of the SmithKline Beecham Quality of Life Scale. A total of 39 survey was returned. All answers were analyzed statistically by ANOVA or t-test. Results: Internal consistency was high, measuring 0.887 for the 23 items. Staffs have, statistically insignificant, relatively high quality of life. Indirect patient contact group and married group scored more higher than the other group. In so far as age, 30s and 40s scored more higher than the others averagely, the higher educated group, the higher quality of life, except factor competence and physical well-being. Conclusion: This study results support that the indirect patient contact group have higher quality of life in competence factor in quality of life. We recommend that the program that lift self-esteem and quality of life should be supplied for direct patient contact group who may have burnout syndrome. It will be necessary to evaluate the quality of life of patients in psychiatric hospital and patients' family members later.