• 한국소음진동공학회논문집
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• 제22권4호
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• pp.383-392
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• 2012

This paper reports the active vibration control of plates using a positive position feedback(PPF) controller with moment pair actuators. The equations of motion of the plates under a force and moment pairs are derived and the equations of PPF controllers are formulated. The numerical active control system is then achieved. The effect of the parameters - gain and damping ratio - of the PPF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the PPF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies without changing the phase behavior. The increase of the damping ratio of the PPF controller leads to decrease the magnitude of the open loop transfer function and to modify its phase characteristics, ie, system stability. Based on the behavior of the gain and the damping ratio of the controller, PPF controller for reduction of the plate vibration can be achieved. Two PPF controllers are designed with their connection in parallel to control the two modes simultaneously. Each PPF controller is tuned at the $1^{st}$ and $2^{nd}$ modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the tuned modes can be obtained.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.148-156
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• 2013

Since the demand for new military vehicle to fulfill the necessary conditions such as multi-purpose, high-mobility, and survivability has raised continuously from the army, the prototype of a Korean light tactical vehicle was developed to meet these requirements using our own technology. In particular, the new tactical vehicle was equipped with a double wishbone independent suspension to improve ride and handling and maximize off-road driving performance. In this paper, a comprehensive virtual durability process to evaluate the service life of the prototype is presented. A reliability of the trimmed body model based on CATIA data was verified by comparison result between mode analysis and modal test. The dynamic model was constructed using ADAMS/Car, and then the weight distribution and lateral slope driving performance of it were compared with the results of static weight and lateral slope tests. The validity of the VTL(Virtual Test Lab) was checked with test results from the 3-inch spaced impact road. The durability performances of trimmed body and suspension components were evaluated through MSM(Modal Superposition Method) fatigue analysis. It is shown that the virtual durability process could be a helpful tool to find out the weak areas and improve their structures in developing new military vehicle.

• Archives of Pharmacal Research
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• 제27권11호
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• pp.1177-1182
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• 2004

The effect of poly[2-methacryloyloxyethyl phosphorylcholine] (pMPC) on the skin permeation property was investigated by performing in vitro skin permeation study of a model drug, nicotinic acid (NA). Effect of pMPC polymer in donor solution on skin permeation rates was evaluated using side-by-side diffusion cells. Also, the structural alterations in the stratum corneum (SC), inter-lamellar bilayer (ILB) and dermis layers in pMPC-treated and -untreated skin sections were investigated with transmission electron microscopy (TEM). The permeation profile of NA without pMPC in donor solution showed biphasic mode: initial $1^{st} phase and 2^{nd}$ hydration phase. The sudden, more than 10-fold increase in flux from the initial steady state (43.5 $\mu g/cm^2$/hr) to the $2^{nd}$ hydration phase (457.3 $\mu g/cm^2$/hr) suggests the disruption of skin barrier function due to extensive hydration. The permeation profile of NA with 3% pMPC in the donor solution showed monophasic pattern: the steady state flux (10.9 $\mu g/cm^2$/hr) without abrupt increase of the flux. The degree of NA permeation rate decreased in a concentration-dependent manner of pMPC. TEM of skin equilibrated with water or 2% pMPC for 12 h showed that corneocytes are still cohesive and epidermis is tightly bound to dermis in 2% pMPC-treated skin, while wider separation between corneocytes and focal dilations in inter-cellular spaces were observed in water-treated skin. This result suggests that pMPC could protect the barrier property of the stratum corneum by preventing the disruption of ILB structure caused by extensive skin hydration during skin permeation study.

• Journal of Preventive Medicine and Public Health
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• 제38권2호
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• pp.132-140
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• 2005

Objectives: To propose a risk-adjustment model from insurance claims data, and analyze the changes in cesarean section rates of healthcare organizations after adjusting for risk distribution. Methods: The study sample included delivery claims data from January to September, 2003. A risk-adjustment model was built using the 1st quarter data, and the 2nd and 3rd quarter data were used for a validation test. Patients' risk factors were adjusted using a logistic regression analysis. The c-statistic and Hosmer-Lemeshow test were used to evaluate the performance of the risk-adjustment model. Crude, predicted and risk-adjusted rates were calculated, and compared to analyze the effects of the adjustment. Results: Nine risk factors (malpresentation, eclampsia, malignancy, multiple pregnancies, problems in the placenta, previous Cesarean section, older mothers, bleeding and diabetes) were included in the final risk-adjustment model, and were found to have statistically significant effects on the mode of delivery. The c-statistic (0.78) and Hosmer-Lemeshow test ($x^2$=0.60, p=0.439) indicated a good model performance. After applying the 2nd and 3rd quarter data to the model, there were no differences in the c-statistic and Hosmer-Lemeshow $x^2$. Also, risk factor adjustment led to changes in the ranking of hospital Cesarean section rates, especially in tertiary and general hospitals. Conclusion: This study showed a model performance, using medical record abstracted data, was comparable to the results of previous studies. Insurance claims data can be used for identifying areas where risk factors should be adjusted. The changes in the ranking of hospital Cesarean section rates implied that crude rates can mislead people and therefore, the risk should be adjusted before the rates are released to the public. The proposed risk-adjustment model can be applied for the fair comparisons of the rates between hospitals.

• Journal of Chest Surgery
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• 제43권2호
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• pp.184-187
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• 2010

압축성 심막염은 개심술 후 드문 합병증이지만 여전히 심장 수술 후 이상적인 치료접근이 필요한 어려운 질환이다. 저자들은 심장 수술 후 우심부전증을 보이는 압축성 심막염 2예를 경험하였다. 심장 초음파 검사에서 보이는 심실중격떨림 현상으로 진단하였고, 두 환자에서 각각 개심수술 40일과 31일만에 좌측 전측방 소절개 개흉술로 심막절제술을 시행하였다. 심막절제술 후 1∼2주일에 걸쳐 심부전증은 서서히 호전되었다. 개심술 후 발생한 압축성심막염에 대해 보존적 내과적 치료방법으로 압축성 증상 및 증후가 호전되지 않는 경우 좌측 전측방 소절개 개흉술에 의한 심막절제술은 효과적인 치료 방법의 하나로 생각된다.

• 한국위성정보통신학회논문지
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• 제7권2호
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• pp.76-79
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• 2012

위성의 전력 시스템은 전력의 생산, 변환 및 분배를 담당하는 주요한 시스템으로, 임무 수명뿐 아니라 임무 횟수, 시기 등의 설계에 사용된다. 이중 전력의 변환을 담당하는 변압기의 부하와 입력 조건에 따라 안정화 설계가 이루어 져야 하지만, 실지 궤도상에서 Test 및 check-out을 진행할 수 없는 특성으로 다양한 입출 조건 변화에 대한 성능 및 안전성을 확인하기위한 방법이 요구된다. 일반적으로 위성 컨버터는 다양한 부하 조건에 따라 설계되므로, 부피 및 설계의 효율성을 위해 다중 출력 및 여러 개의 stage를 거쳐서 전력 변환이 이루어지게 된다. 하지만, 이로 인해 분석에 많은 어려움을 지니게 되어 직관적인 회로의 파악은 쉽지 않게 된다. 또한 일반적인 분석으로는 모든 상태 방적식의 해를 구하기 쉽지 않아서 실제 운용 시에 가해질 수 있는 소자에 대한 영향성에 대한 분석이 힘들 수 있게 된다. EDF model은 fundamental 주파수 분석을 통해 모든 소자에 대한 분석이 가능한 방법이며 multi-stage의 경우에도 입력 모델링으로 한꺼번에 1st stage와 2nd stage의 분석이 가능한 방법이다. 본 논문에서는 EDF 방법을 통한 modeling과 시뮬레이션 modeling을 비교하여 적용의 타당성을 분석하고, 이를 통해 제어기를 설계하여 multi-stage 컨버터의 직관적인 회로 분석이 가능함을 확인 하였다.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.309-313
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• 2008

We studied the sapphire and germanium fibers to determine which optical fiber best transmits Erbium:YAG laser for intracorporeal lithotripsy. Human calculi were ablated with an Erbium:YAG laser in contact mode using two fibers. Optical outputs at the distal end of fibers were measured before and after laser lithotripsy. Upon the irradiation on the calculus with the 50 mJ and 100 mJ pulse energy, the output energy at the distal end of germanium fiber declined to approximately 50% of the input energy. For the sapphire fiber, the output energy at the distal end remained unchanged with 100 mJ input energy; however the output energy had dropped to 50% for 200 mJ input energy. In order to examine how the types of target tissue affect the fiber damage, the sapphire fiber was tested for the irradiation on soft tissue and water as well. No energy decline was observed during soft tissue and water irradiation. We also characterized ablation craters with both optical fibers. Both fibers produced similar craters on calculi in terms of depth and diameter. Sapphire fibers are better suited than germanium fibers for Erbium:YAG lithotripsy in terms of the fiber damage.

• 비파괴검사학회지
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• 제20권4호
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• pp.314-321
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• 2000

모의 원자로내 용융물 냉각 실증 실험 결과 용융물 $Al_2O_3/Fe$ thermite 와 lower head vessel사이에 간극이 발생된다. 간극을 정량적으로 측정하기 위한 기존의 초음파 방법은 구조물의 복잡성과 $2300^{\circ}C$ 에서 용융되는 thermite $Al_2O_3/Fe,\;Al_2O_3$의 영향으로 발생되는 lower head의 열영향부위(HAZ)의 금속학적인 결정입자 크기의 변화로 결정 계면으로부터 발생되는 잡음신호와 초음파 산란, 감쇠, 모드 변환 등이 발생되어 신뢰성이 떨어지고 있다. 간극을 정량적으로 측정하기 위해서 thermite와 lower head 사이에 물이 채워진 형태의 즉 고체, 액체, 고체의 다층구조에서 초음파의 진행 및 반사 형태를 분류 및 분석하였다. 결정립의 잡음을 억제하기 위하여 주파수대역의 확률 처리 방식인 PT(polarity threshold) 알고리즘을 이용하여 약 6dB 신호 대 잡음비의 개선효과를 가져왔다.

• KEPCO Journal on Electric Power and Energy
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• 제2권4호
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• pp.577-582
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• 2016

최근 급속한 녹색환경 정책으로 LED를 이용한 조명 광원들이 설치 운용하고 있으나, 이들 광원의 전원 공급은 안정된 직류 전원 공급을 위해서 스위칭 모드 전원 공급(SMPS) 장치로 전원을 공급하고 있다. 그러나, 이들 전원 공급 장치는 공급 단가 때문에 설계 및 설치과정에서 스위칭에 따른 전력과 변환역률, 전기적 노이즈 및 돌입전류들은 간과하고 있다. 따라서, 본 연구에서는 SMPS는 고품질의 전원을 LED 조명 부하에 공급하기 위하여 스위칭 시에 다음과 같은 3가지 관점에서 회로를 연구하였다. 첫 번째, 역률과 효율을 약 85% 확보하고, 두 번째, 노이즈(고조파 포함) 최소화, 세 번째는 스위치-온 시 3A 돌입전류를 $100{\mu}sec$ 후 최소 0.3 A로 감소하여 돌입 전류 침입을 최소화 하고자 하였다. 본 연구에서는 IC형 구동기(LNK 409)를 적용하여 입력전압과 출력상황을 귀환 형태로 감시하도록 하였으며, 정전류 출력을 위하여 정전압을 유지할 수 있는 제어회로와 시상수를 개발하였다. 그러나, 부하 변동 시 미세한 전류의 불규칙으로 인한 발열 문제는 해결하지 못하고 있다. 이를 증명하고자 LED 조명 부하 46 W급을 대상으로 효과를 검증하였다.

• 복식문화연구
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• 제2권2호
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• pp.395-413
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• 1994

Costume is mirror of diverse life styles and attitudes in human life. It has a meaning beyond "clothing" . Fashion illlustration is to express these costumes with a picture. So, it can be said that it is a ′mirror of costumes′ in historical side. The purpose of this study is to find the meaning of fashion illustration of 17th century, which called its first one and to look into its characteristics and costumes of 17th century respotlighting fashion illustrators and painters related with fashion illustration in those days. This study is based on Western Europe by literatures. The fashion illustration in 17th century designed by painters and fashion illustrators. They are Wenceslaus Hollar, Abraham Bosse, Jacques Callot, Jean de st Jean, N. Bonar, A. Trouvain, A. Arnoult in France and so on. The characteristics of fashion illustration in 17th century are as follows : 1. There was a quickening of modern civil consciousness in 17th century. As the subject of costume culture moved from noble class to the working class which began to have a free, the fashion illustration changed to the direction of informing their social class and job. 2. The fashion illustrations of 17th century showed storng realism which was a base of modern picture. 3. The most of them showed costume plates. It was not to transmit adding intended forecast but to describe sincerely in costumes′ record. However, the fashion illustration since the middle of 17th century was designed considering fashion. 4. It could be said that the fashion illustration of 17th century was the forest one of today. It was expressed by Wenceslaus Hollar′s ones. And it is found in his suggestion of popular costumes before and behind and delicate description like accessories. 5. They were transmitted by fashion magazines internationally. Le Mercure Galant, which printed mode plates in 1678, was the first modern fashion magazine aiming at general readers. The fashion illustration of 17th century can divide into ones for court, for working classes, costume plates. The fashion illustrations for court designed by court painters. There were court costumes of early time, spanish Mode and of lately time, French Court Culture. They had baroque elements with a bunddle of ribbons and race decoration. On the other hand, the fashion iooustrations for working class were under the influence on Netherlands styles. They were designed for the purpose of god function and much use. That′s why was under the influence of puritanical life creed. In this situation, the costume plates directed the fashion in those days. At that time, they were supplied widely and it amy be an attempt of popularization. The fashion illustrations of 17th century appeared that they had transmissible character and artistics expression. On the basis of them, we can look into the fashion illustrations of today.