• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.247-251
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• 2003

In this paper, we propose an approximation of the M/G/1 system with finite workload capacity, where customers whose admission to the system would increase the workload beyond a prespecified finite capacity limit are not accepted. Our approximation method is based on the idea that the service time of a customer in the M/G/1 system can be approximated as the sum of service times of a batch of customers in the $M^{X}/d/1$ system where the service time is deterministic and very small. That is, the original service time is discretized and approximated by the batch size. We exemplified our method by obtaining the average workload of the M/M/1 system by means of the $M^{X}/d/1$ system, where the batch size is geometric. In addition, the approximate blocking probabilities of the M/M/1 and $M/E_{k}/1$ system with finite workload capacities are sought. The proposed method turns out to give a good approximation, which is compared with a simulation.

• The Journal of Internal Korean Medicine
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• v.13 no.1
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• pp.181-194
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• 1992

In order to study oriental medical literature and clinical effects of Chungsimondamtang, the experiments of analgesic action, sedative action, anticonvulsive action, action on the isolated ileum, action on the circulatory system and hyperlipidaemia were observed. The results were as follows: 1. The analgesic effects were significantly noted. 2. The prolongaton of hypnotic time was noted. 3. The inhibitory effects on the convulsion induced by strychnine, picrotoxin and caffeine were significantly recognized. 4. The spontaneous momentum of isolated ileum was evidently inhibited, and recognized anti Ach. and anti Ba. effects. 5. The effects of descending blood pressure in normal rats and anesthetized rabbits were strongly recognized. 6. The effects of inhibition on the increase of TG. and TC. levels in hyperlipidaemia rats induced by Triton WR-1339 was significantly recognized. 7. The effects of inhibition on the increase of TG. and TC. levels in hyperlipidaemia rats induced by 75% fructose was significantly recognized. With the genelalization of the above-mentioned experimental results, literatual and clinical effects of Chungsimondamtang were approximate to actual experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.582-591
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• 2001

It is known that the reduced integration, modified shape function, anisoparametric and non-conforming element can reduce the error induced by stiffness locking phenomenon in the finite element analysis. In this study, we propose new anisoparametric curved beam element. The new element based on reduced minimization theory is composed of different shape functions in each displacement field. By the substitution of this modified shape function, the unmatched coefficient that cause stiffness locking in the constraint energy is eliminated. To confirm the availability of this new model, we performed numerical tests for a simple model. As a result of numerical test, the undulate stress patterns are disappeared in static analysis, and displacements and stresses are close to exact solution. Not only in the static analysis but also in the eigen analysis of free vibrated curved beam model, this element shows successful convergent results.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.65-72
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• 2009

The new method is proposed to improve high speed detection of grid voltage phase and magnitude during a voltage dip due to a grid faults. Usually, A LPF(Low Pass Filter) is used in the feedback loop of PLL (Phase Locked Loop) system because the measured grid voltage contains harmonic distortions and sensor noises. so, a new design method of the loop gain of the PI -type controller in the PLL system is proposed with the consideration of the dynamics of the LPF. As a result, a better transient response can be obtained with the proposed design method. The LPF frequency and PI controller gain are designed in coordination according to the steady state and dynamic performance requirement. This paper shows the feasibility and the usefulness of the proposed methods through the computer simulation and the lab-scale experiments.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.218-220
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• 2006

Sn-3.0Ag-0.5Cu solder is widely used as micro-joining materials of flip chip package(FCP) because of the fact that it causes less dissolution and has good thermal fatigue property. However, compared with ternary electroplating in the manufacturing process, binary electroplating is still used in industrial field because of easy to make plating solution and composition control. The objective of this research is to fabricate Sn-3.0Ag-0.5Cu solder bumping having accurate composition. The ternary Sn-3.0Ag-0.5Cu solder bumping could be made on a Cu pad by sequent binary electroplating of Sn-Cu and Sn-Ag. Composition of the solder was estimated by EDS and ICP-OES. The thickness of the bump was measured using SEM and the microstructure of intermetallic-compounds(IMCs) was observed by SEM and EDS. From the results, contents of Ag and CU found to be at $2.7{\pm}0.3wt%\;and\;0.4{\pm}0.1wt%$, respectively.

• Journal of Chest Surgery
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• v.43 no.3
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• pp.300-303
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• 2010

A thrombus in the aorta is a rare condition that is generally detected after cerebral, visceral or peripheral emboli. We reported here on two cases of aortic thrombus with myocardial infarction.

• Journal of Chest Surgery
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• v.43 no.2
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• pp.176-179
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• 2010

Cardiac papillary fibroelastomas are the second most common primary tumor of the heart and they most commonly affect the left cardiac valves. However, occurrence of this tumor on the right side of the heart has been rarely reported, with only a few cases having been documented on the pulmonary valve. We present here a rare case of a papillary fibroelastoma that occurred on the pulmonary valve and this was successfully managed by replacing the pulmonary valve in a patient with congestive heart failure.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.442-449
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• 2006

탈 장르화와 영상의 다양화로 예술에서의 표현의 한계는 극대화 되고 있으며, 디지털 매체를 통한 인터랙션 역시 디지털 아트에서의 보편적인 표현 방법으로 전환 되었다. 예술에서의 상호작용은 보여주는 것에서 참여하는 것으로의 전환을 꿰 하고 있고, 디지털을 기반으로 한 다매체, 다중화가 이를 뒷받침 한다. 상호작용을 위한 디지털 아트 작품을 위해서는 센서를 이용한 표현방법들이 있으나, 기타의 센서도구를 사용치 않고, 단지 카메라로부터 입력된 신호만을 기반으로 영상과 관객의 상호작용을 끌어 낼 수 있다. 이를 위해서는 모션트레킹을 위한 알고리즘을 응용함으로써 사물의 밝기 값에 충족한 데이터를 만들어 낼 수 있고 그에 해당하는 밝기의 변환 값을 이용해 미세한 사물의 변화를 감지 할 수 있는 것이다. 이런 일련의 영상작업을 위해서는 사물의 움직임과 반복성을 얼마만큼 인지하고 감지 해내느냐고 관건인데, 다시 말해 한번 측정한 움직임이 있는 사물의 데이터도 프로그램상에서 계속하여 인지가 되어야 하고, 그 데이터 값을 영상으로 반환하여야 하는데, 이는 영상의 지속적인 변화를 가져 올 수 있다는 걸 의미한다. 따라서 본 논문에서는 모션 트래킹의 기본 알고리즘을 제시하고 영상작품과 인턱래션작품의 변환를 위해 사용된, 센서 대체도구인 웹 캠의 데이터 즉, 색상 값과 밝기 값을 적절하게 활용함으로써 표현의 다양성을 이끌어 내고 디지털 인터랙티브 작품으로써의 제작을 꾀하고자 한다.

• Current Industrial and Technological Trends in Aerospace
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• v.4 no.1
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• pp.34-43
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• 2006

헬기는 비행에 필요한 추력, 모멘트 및 조종력을 회전하는 로터시스템에서 발생시키기 때문에 근본적으로 진동이 많이 생기는 항공기이다. 로터시스템의 회전에 의해 발생되는 진동소스를 제어함으로써 헬기 동체에 전달되는 진동을 감소시키고자 하는 연구들이 지금까지 수많이 진행되었다. 이러한 연구들을 크게 두 가지로 분류하면, 수동적 진동제어 방법과 능동적 진동제어 방법으로 나눌 수 있다. 수동적 진동제어 방법은 그간 오랫동안 연구되어 현재 운용 헬기에 실제적으로 적용되고 있으나 능동적 진동제어 방법은 최근까지 활발한 연구가 진행되고 있는 상태이다. 본 논문의 서론에서는 헬기 진동제어를 위한 일반적인 방법에 대한 개요를 소개하였다. 본문은 로터시스템 진동제어 기술 중 최근까지 연구가 진행되고 있는 능동적 진동제어 방법을 중심으로 기술하였다. 특히 최근 비행시험에 성공하여 거의 실용화 단계에 이르고 있는 PZT를 이용한 Trailing Edge Flap 기술, Active Twist Rotor 등을 중점적으로 소개하였다. 마지막으로 유로콥터 BK117의 ADASYS 로터 시스템 성공사례 및 향후 해결해야 할 기술적 제한사항 등을 간략하게 기술하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.4003-4012
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• 1996

Hydro dynamically developing and simultaneously (hydro dynamically and thermally) developing laminar flows of a Bingham plastic in a circular pipe have been investigated numerically. Solutions have been obtained by using a four-step fractional method combined with an equal order bilinear finite element method. For the hydro dynamically developing flow, shorter entrance length is required to reach fully developed velocity field for larger yield stress and non-monotonic pressure drop along the pipe centerline is observed when the yield stress exceeds a certain critical value. For the simultaneously developing flow, the heat transfer characteristics show the same trends as those predicted for the thermally developing flow (Graetz problem).