• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.22-28
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• 2009

Recently, there has been an active study about smart fluid to control the vibration, in which MR fluid is evaluated as most efficient because it can generate different bonding forces based on the intensity of the external magnetic fields. This paper attempts to find a mechanism that, under limited conditions during a clutch production that uses such dynamic characteristic, defects the maximum intensity of electromagnetism. Using the finite element analysis program, we predicted a change within the bonding force of the MR fluid occurring inside the clutch when it is subjected to an increased electric current. In addition, we analyzed the change in the magnetic intensity when the coil comprising the coil control center is switched to multiple lines from the standard single line, to find a mechanism that can maximize the effect. Based on this analysis, we developed the clutch and tested its function, hoping to widen future MR fluid's range of application.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1511-1517
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• 2008

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid's cohesiveness. The core can be said to determine the magneto-rheological fluid damper's performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.

• Journal of Energy Engineering
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• v.9 no.3
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• pp.202-211
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• 2000

본 연구는 다양한 각도를 가지는 와이어코일을 사용하여 관내 단상 열전달 촉진 및 압력강하 특성 실험을 수행하였다. 작동유체는 순수 물과 에틸렌글리콜을 체적비율로 50% 혼합하여 사용하였으며, 시험부 관지름은 11mm와 13.88mm이고, 시험부 길이는 760mm를 사용하였다. 평활관과 와이어코일을 삽입한 열전달촉진관에 대한 관내 열전달계수와 마찰계수는 실험에서 측정한 온도, 유량, 압력강하 값을 기초로 구하였다. 와이어코일에 대한 거친표면해석을 수행하였으며, 그 결과를 거칠기 래이놀즈수에 대한 운동량전송 거칠기함수와 열전달 거칠기함수로 표현하였으며 이에 대한 상관식을 제시하였다. 이 상관식들은 거칠기 레이놀즈수, 코일 각도, 프란틀수의 함수로 표현하였다.

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.545-550
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• 2023

A pretensioner is a safety device that protects occupants by pulling the seat belt in the event of a vehicle collision. However, since the pretensioner is driven by a explosive method, it is necessary to replace not only the gas generator but also all connecting parts including the manifold after an accident. Therefore, in this paper, we propose an elastic force-based pretensioner that can be used safely and semi-permanently. After analyzing the operating mechanism of the existing pretensioner from a thermodynamic/dynamic point of view, the spring stiffness that can be deployed within an appropriate operating time was determined by converting the gas explosion energy into elastic energy. In addition, the coil spring shape that satisfies the elastic stiffness was designed in consideration of the vehicle interior installation standard. Finally, the operating performance of the pretensioner driven by elastic force was verified through fabrication.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1997.10a
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• pp.114-121
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• 1997

회전 열파이프의 열전달 성능은 액막 두께 및 증발부로 귀환되는 응축 액막 유동율에 의해 결정된다. 그 동안 응축액 유동율을 촉진시키기 위하여 용기 내벽에 groove, 테이퍼 및 나선형 코일을 삽입하여 유동율을 높이는 방법들이 연구되었다. 본 연구도 회전 열파이프의 내부 관벽 구조에 관한 것으로써 삼각 단면을 갖는 회전 열파이프의 열전달 특성을 파악하고자 하였다. 삼각 단면을 갖는 회전 열파이프는 고속 회전 영역에서 모서리 부분으로 액막이 집중되어 관 내벽에 형성되는 액막 두께를 줄일 수 있으나 증발부에서 국부적인 과열이 발생되어 불안정한 작동 상태를 나타내었다. 따라서 본 연구에서는 개선방안으로 증발부에 부분적으로 원형관을 접합하였으며, 그 결과 dry-out의 억제와 함께 삼각 유동 단면에 의한 액막 두께 감소 효과를 볼 수 있었다. 회전체 발열부 냉각에 적용시키기 위해서는 앞으로 최적의 기하학적 형상에 따른 충전율 및 액막에서의 열전달에 대한 정량적인 해석 연구가 필요할 것으로 생각된다.

• Journal of Energy Engineering
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• v.4 no.2
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• pp.261-269
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• 1995

본 연구에서는 밀폐형 2상 열사이폰의 액체 Pool에서 발생하는 핵비등현상과 유동영역에 대해 가시화 방법으로 연구하였다. 실험용 열사이폰은 스텐레스와 유리관을 이용하여 제작하였으며, 열공급은 증발부 주위에 설치된 유도 가열용 코일에 고주파를 가함으로써 스텐레스 외면에 발열이 일어나도록 하였다. 이에 따른 결과는 다음과 같다. 실험용 열사이폰은 고주파 가열등 열사이폰의 작동성능을 저해하는 여러 요인들이 포함되어 있었으나, 실험결과 이러한 문제는 실험 내용에 영향을 미칠만큼 크게 나타나지 않았다. 열속과 상당압력의 범위는 각각2$m^2$, 0.1

• Journal of Energy Engineering
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• v.8 no.2
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• pp.325-332
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• 1999

When a rotating heat pipe is in operation, liquid condensate returns from the condenser to the evaporator along the inside surface by both components of gravitational and centrifugal forces. It was known that its performance was largely dependent on how to increase the flow rates of condensate and keep the condensate film thickness as thin as possible. Most of research works were focussed on this goal, and various inner wall structures such as tapered wall, stepped wall or coil inserted pipe etc. were developed. In the present study, a stepped wall structure with 3 internal grooves in the condenser and adiabatic zone was examined. For this system, the condensate would flow down to the evaporator through the grooves, resulting a reduced film thickness over the condenser surface. Experimental data showed an enhancement of heat transfer coefficient in the condenser zone. An analytical solution to the condensate film thickness showed that the analytically calculated values of heat transfer coefficient were considerably higher than the experimental data.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.149-151
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• 2006

고주파 유도가열은 무공해 에너지 절약을 기본으로 하는 전기가열의 한 방법으로 환경 친화와 에너지 절감에 많은 기대를 하고 있다. 본 논문에서는 절연체 용기내에 특수 발열체 부하를 수납하여 외부의 코일과 비접촉상태로 전자유도에 의해 와전류를 발열체에 흘림으로서 발열하게 되는 새로운 방식을 제안하였다. 설계한 인버터는 스위칭 주파수 20[kHz] 대역에서 작동되는 고주파 직렬 부하 공진형이며 LC 공진 설계에서 L을 부하로 설정하여 효율을 최대화 하였다.

• Fire Science and Engineering
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• v.28 no.5
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• pp.8-13
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• 2014

The purpose of this study is to analyze the damage pattern when overcurrent is applied to a thermal magnetic type molded case circuit breaker (MCCB) using a Primary Current Injection Test System (PCITS). When an overcurrent of 150 A was applied to the PCITS for 5 seconds with the trip bar of an MCCB being damaged, it was found that the surface of the temperature control device (bimetallic strip) positioned at the right was significantly carbonized. When an overcurrent of 300 A was applied to the PCITS for 5 s under the same conditions, the entire temperature control device was deteriorated, becoming flattened and in close contact with the MCCB. When an overcurrent of 450 A was applied to the PCITS for 5 s, the coil of the temperature control device was melted and disconnected. In addition, it was observed that the contacts, the enclosure and upper cover were deformed and there was a trace of carbonization on them. When approximately 3 s had elapsed after an overcurrent of 600 A was applied, white smoke occurred inside the MCCB and a flame was radiated out, after which the overcurrent supply stopped with "phutt" (whomp) sound. It was observed that when the same type of MCCB is damaged by a general flame, the surfaces of its handle, terminal, arc divider (extinguisher) and temperature control device were carbonized uniformly. In addition, it was found that the trip bar of the operating mechanism was melted down and the metal operation pin was moved while being tripped.