금속이온 치환법으로 제조된 티타니아를 이용한 유기물 분해에 대한 연구

이규환,이동석 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

In recent years, much attention has been paid to "Photocatalytic oxidation" as an alternative technique, where the pollutants are degraded by UV-irradiation in the presence of a semiconductor suspension such as titanium dioxide. TiO_(2) is the most often used photocatalyst due to its considerable photocatalytic activity, high stability, non-environmental impact and low cost. In this research, the photocatalytic degradation of humic acid, acetaldehyde and methylene blue in UV/TiO_(2) systems has been stydied. The effect of calcination temperature for manufacturing of TiO_(2) Photocatalysts and type of photocatalysts on photodegradation has been investigated. Photocatalysts with various metal ions(Mn, Fe, Cu and Pt) loading are tested to evaluate the effects of metal ions impurities on photodegradation. The photodegradation efficiency with Pt-TiO_(2) or Fe-TiO_(2) or Cu-TiO_(2) is higher than Degussa P-25 powder. However, the photodegradation efficiency with Mn-TiO_(2) is lower than Degussa P-25 powder. The photocatalytic properties of the nanocrystals were strongly dependent upon the crystallinity , Particle size, standard reduction potential of various transition metal and electronegativity of various transition metal. As a result photocatalysts with various metal ion loading evaluated the effect of photodegradation.

난분해성 유기물질 제거를 위한 오존/촉매 공정의 비교에 관한 연구

이규환,이유미,이동석 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.B

Ozone alone and catalytic ozone processes were introduced for treatment of humic acid, which is representative refractory organic compound. The treatment efficiencies of humic acid in each process were analyzed in pH variation, DOC removal, and UV_(254) decrease. Mn loaded CAC catalyst was prepared by loading potassium permanganate onto the granular activated carbon surface. BCM-GAC and BCM-Silicagel catalyst were prepared by BCM. UV_(254) decrease in all processes was comparatively high with efficiency over 87%. DOC removal in ozone/GAC process was the highest with 78%, and removal rated for other processes followed the order ozone/BCM-GAC(62%) > ozone/BCM-silica gel(45%) > ozone/silica gel(43%) > ozone/Mn Loaded GAC(42%) > ozone alone(37%).

디지털 구현에 의한 SVPWM 인버터의 출력특성 해석

이동희,오석규 진주산업대학교 2000 論文集 Vol.39 No.-

Recently, PWM inverter are much used in the motor control, UPS and factory automation. Of the various pulse programming methods, the carrier based PWM methods are the preferred approach in most applications due to the low harmonic distortion waveform characteristics with well defined harmonic spectrum, the fixed switching frequency, and implementation simplicity. In this paper, analysis of digital implemented SVPWM VSI inverter is provided. Output voltage error, current ripple characteristics and deadtime effects of digital implemented SVPWM VSI inverter are simulated for d.c. link voltage. With fixed high d.c. link voltage has high current ripple in low speed region because of voltage resolution and low back e.m.f. and dead-time effect more serious in the low speed range. Analytical results are verified in the sensorless speed control of PMSM.

UV/TiO_(2) 수처리 공정에서의 살균에 관한 연구

이규환,이상진,이용재,이동석 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A

This study investigated disinfection effect by general water purifier and water purifier with UV light disinfection. The results are as follows : (ⅰ) The general bacteria existed plentifully in a storage tank before treatment (ⅱ) Water treated in water purifier did not meet the water treatment regulation standard since the presence of bacteria, whereas with UV light application the regulation standard is totally satisfied. (ⅲ) Photocatalytic disinfection process with UV light in the presence of TiO_(2) more effectively killed general bacteria than UV light only.

난분해성 유기물질 제거를 위한 오존/촉매 공정의 비교에 관한 연구

이규환,이유미,이동석 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

Ozone alone and catalytic ozone processes were introduced for treatment of humic acid, which is representative refractory organic compound. The treatment efficiencies of humic acid in each process were analyzed in pH variation, DOC removal, and UV_(254) decrease. Mn loaded GAC catalyst was prepared by loading potassium permanganate onto the granular activated carbon surface. BCM-GAC and BCM-Silica gel catalyst were prepared by BCM. UV_(254) decrease in all processes was comparatively high with efficiency over 87%. DOC removal in ozone/GAC process was the highest with 78%, and removal rates for other processes followed the order ozone/BCM-GAC(62%) > ozone/BCM-silica gel(45%) > ozone/silica gel(43%) > ozone/Mn Loaded GAC(42%) > ozone alone(37%).

가변 링크전압을 이용한 영구자석 동기전동기의 토오크 리플 저감 제어

이동희,오석규 진주산업대학교 2000 論文集 Vol.39 No.-

Permanent magnet synchronous motors are widely used in high-performance drive applications such as industrial robots and machine tools because of their high-power density, high-torque/inertia ratio, and free maintenance. In recent sensorless and torque ripple reduction control are much studied for high-performance control. In this paper, A variable link voltage system is introduced for reduction of torque current ripple of PMSM. The PWM VSI inverter system with fixed high d.c. link voltage has high current ripple in low speed region because of voltage resolution and low back e.m.f. and dead-time effect more serious in the low speed range. The proposed variable link voltage inverter system controls the d.c. link voltage applied in the inverter input terminals according to the back e.m.f. of the motor and load conditions. In the low reference voltage command, variable link voltage system down the d.c. link voltage and up the d.c. link voltage in the high reference voltage command. So the time of the effective voltage vector in the SVPWM inverter remains constantly in the low speed range and voltage error and current ripple are decreased. The proposed algorithm is verified by simulation and experimental results.

장기입원환자 관리 방해요인

이경석,윤석만,권희,이호,김혜경,조미자,한규남,김명성 순천향의학연구소 2003 Journal of Soonchunhyang Medical Science Vol.9 No.1

Background: Recently the health insurance review agency tried to cut off the cost of unnecessary hospital stay. It is important to reduce the prolonged occupation of the hospital beds. However, there are some obstacles of the management for the prolonged bed occupation. We report our experiences and the problems of bed-control. Methods: To increase the rate of effective bed-usage, a task force was made. This team was consisted of 4 dctors, 2 nurses and 2 personnel of the administrative department. From December 20th 2001 to May 17th 2002, the task force analysed the rate, number and causes of the prolonged (more than 60 days, regardless of the disease entities) bed occupation. We announced and explained the necessity of bed-control and actively pressed to reduce the prolonged bed occupation. Results: The number of the prolonged bed occupation was 71 at the beginning of the management. It was reduced to 46 at best, then turned back to 65 at the end. It seems to be impossible to reduce the prolonged bed occupation until there are sufficient numbers of long-term care facilities. Aggressive bed control makes the sick patients to move every two or three months, it is never desirable. Conclusion: We cannot expect any Quality Improvements without improvement of the wrong system. Prior to the management for the prolonged bed occupation, it is necessary to build a sufficient number of long-term care facilities.

Equisetum arvense L.이 고혈당 쥐의 혈중 포도당 농도에 미치는 영향

이현자,김석환,손기호,강우규,최종원 慶星大學校 環境問題硏究所 1992 環境硏報 Vol.2 No.1

The effect of methanol extract of Equisetum arvense L.(EM) on blood glucose level in streptozotocin-induced diabetic rat and acute toxicity of EM were investigated. Male Sprague-Dawley rats(200∼250g), with free access to commercial rat chow and water, were divided into four groups: Group 1 served as control; Group 2 received STZ only: Group 3 received EM only; Group 4 received pretreatment with EM followed by STZ administration. EM did not affect the normal blood glucose level and LD50 was about 6,250㎎/㎏. EM pretreatment in STZ-induced diabetic rats slightly inhibited Weight loss and water consumption. EM pretreatment in STZ-induced diabetic rats slightly inhibited the rise of serum glucose concentration. Serum transaminase(AST, ALT) and sorbitol dehydrogenase(SDH) were slightly increased by STZ induced changes in the serum glucose level.

C 의과대학에서 문제강의에 대한 학생들의 직접평가가 강의개선에 미친 영향

김석용, 이상진, 최재운, 김승렬, 김용대, 배성은, 김영규 충북대학교 의과대학 충북대학교 의학연구소 2012 忠北醫大學術誌 Vol.22 No.1

연구목적: 팀티칭에 근거한 통합강의는 최근 대부분의 의과대학에서 시행되는 강의형태이다. 그러나 기 존에 사용되고 있는 온라인 강의평가 방식은 이러한 강의 특성에서 나타나는 문제점을 파악하기 힘든 점이 있다. 본 대학에서는 팀티칭에 의한 통합강의에서 문제강의를 직접적으로 파악하는 ‘문제강의 직 접평가지’를 개발하였다. 본 연구의 목적은 새로이 개발된 문제강의 직접평가지가 강의개선에 끼친 영 향력을 알아보고자 하는 것이었다. 연구방법: 2007년 2학기부터 2009년 2학기까지 충북대학교 의과대학 1, 2학년을 대상으로 문제강의 직접평가지에 의한 강의평가를 실시하였다. 평가지 질문 중에서 두 가지 객관식 질문에 대한 답변을 분 석대상으로 선택하였다. 질문은 첫째, ‘가장 유익하고 도움이 많이 되었던 강의들은 무엇입니까?’와 둘 째, ‘가장 어렵거나 이해하기 힘들었던 강의들은 무엇입니까?’였다. 강의평가를 실시한 강좌들 중에서 2 년 이상 연속적으로 강좌구조와 평가지의 객관식 질문 형식이 변하지 않은 14개의 강좌를 분석대상으로 하였다. 각각 연도의 평균 긍정비율을 다른 연도의 것과 카이제곱 검정 방법을 사용하여 비교하였다. 결과: 14개의 강좌 중에서 시작연도와 마침 연도 간에 긍정비율이 증가된 경우는 13개 강좌였다. 그 러나 통계적으로 의미가 있는 경우는 5개 강좌에서 나타났다. 결론: 문제강의 직접평가지에 의한 문제강의를 판별해 내는 방법은 단기간에 통합강좌의 개선에 효과 적이다.

송전선로에 있어서 상호작용을 고려한 디지털 거리계전기의 신뢰도 향상

이재규,유석구 漢陽大學校 工學技術硏究所 1998 工學技術論文集 Vol.7 No.1

In this paper, the digital distance relay of parallel transmission lines under single-phase-to-ground fault conditions is discussed. Distance relay is used to protect the transmission lines. The priciple of distance relay is well-known; the impedance measured by a relay is proportional to the distance from the relay to the fault point. Hence, by measuring the impedance, it can be determined whether the line is faulted or not. Unfortunately, the measurment of the fault distance is distorted by mutual coupling. To improvement more reliable and practical digital distance relay, the mutual coupling effect has to be considered.