• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.96-100
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• 2008

In this paper, a experimental and theoretical study is carried out on the hydroelastic vibration for a rectangular bottom and side plate of tank. It is assumed that the tank wall is clamped along the plate edges. The fluid velocity potential is used for the simulation of fluid domain and to obtain the added mass due to plate vibration. It is assumed that the fluid is imcompressible and inviscid. Assumed mode method is utilized to the plate model and hydrodynamic force is obtained by the proposed approach. The coupled natural frequencies are obtained from the relationship between kinetic energies of a wall including fluid and the potential energy of the wall. The theoretical result is compared with the three-dimensional finite element method. In order to verify the result, modal test was carried out for bottom/side plate of tank model by using impact hammer. It was found the fundamental natural frequency of bottom plate is lower than that of side plate of tank and theoretical result was in good agreement with that of commercial three-dimensional finite element program.

• 한국해양공학회지
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• 제30권4호
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• pp.277-286
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• 2016

The first part of this study found the tendencies of the mechanical properties of two arctic structural steels (EH32 and FH32). In the second part, the crashworthiness of stiffened panels scaled down from the side frame structure of a Korean research icebreaker was determined. A procedure for designing the shapes and sizes of the stiffened panels, mass and shape of a drop striker, and a large temperature chamber, and then manufacturing these, is introduced in detail. From impact bending tests for the stiffened panels, the residual permanent deformations and deformation histories over time were captured using manual measurement and video image analyses. Numerical simulations of the impact bending tests were carried out for three different finite element models, which were mainly composed of shell elements, solid elements, and solid elements, with welding beads. It was proven from a comparison of the test results and numerical simulation results that the solid element model with the welding bead consideration approached the test results in terms of the residual deformations as long as the strain rate effect was taken into account.

• 대한통합의학회지
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• 제1권1호
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• pp.1-9
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• 2013

Purpose : The purpose of this study is to investigate the impact on the ability to walk, balance after side walking training of hemiplegic patients caused by stroke. Method : The subjects were training before stroke onset whether more than one year elapsed 15 patients with chronic stroke patients, and Berg balance scale(BBS) and Timed up and go test(TUG), Functional reaching test(FRT), 20m walking time 200m walking time were measured and recorded. Training period, a total of three weeks, and training frequency circuit training times 10 minutes per training, 5-minute break, the 10-minute training total 25-minute training was conducted. Gait line of 3m to be based on the patient's side walking, and the risk of falling compared to the presence of the experimenter trained under was carried out. Result : 1. TUG, 2. 20m walking time, 3. 200m walking time 4. FRT, 5. All showed significant improvement in BBS. Judging from the results, the side walking training conducted three weeks due to chronic stroke hemiplegic patient's ability to balance and showed a positive effect on the improvement of walking ability. Conclusion : Accordingly, it was more effective to train hemiplegic patients with chronic stroke on side walking.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.112-119
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• 2006

This paper is concerned with the light-weight design of a center-pillar assembly for the high-speed side impact of vehicle using advanced high strength steels(AHSS). Steel industries continuously promote the ULSAB-AVC project for applying AHSS to structural parts as an alternative way to improve the crashworthiness and the fuel efficiency because it has the superior strength compared to the conventional steel. In order to simulate deformation behavior of the center-pillar assembly, a simplified center-pillar model is developed and parts of that are subdivided employing tailor-welded blanks(TWB) in order to control the deformation shape of the center-pillar assembly. The thickness of each part which constitutes the simplified model is selected as a design parameter. Factorial design is carried out aiming at the application and configuration of AHSS to simplified side-impact analysis because it needs tremendous computing time to consider all combinations of parts. In optimization of the center-pillar, S-shaped deformation is targeted to guarantee the reduction of the injury level of a driver dummy in the crash test. The objective function is constructed so as to minimize the weight and lead to S-shape deformation mode. Optimization also includes the weight reduction comparing with the case using conventional steels. The result shows that the AHSS can be utilized effectively for minimization of the vehicle weight and induction of S-shaped deformation.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.84-92
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• 2005

This paper is concerned with optimum design of a center-pillar assembly induced by the high-speed side impact of the vehicle. In order to simulate deformation behavior of the center-pillar assembly, simplified finite element model of the center-pillar and a moving deformable barrier are developed based on results of the crash analysis of a full vehicle model. In optimization of the deformation shape of the center-pillar, S-shaped deformation is targeted to guarantee reduction of the injury level of a driver dummy in the crash test. Tailor-welded blanks are adopted in the simplified center-pillar model to control the deformation shape of the center-pillar assembly. The thickness of each part which constitutes the simplified model is selected as a design parameter. The thickness of parts which have significant effect on the deformation mechanism are selected as design parameters with sensitivity analysis based on the design of experiment technique. The objective function is constructed so as to minimize the weight and lead to an S-mode deformation shape. The result shows that the simplified model can be utilized effectively for optimum design of the center-pillar members with remarkable saving of computing time.

• 한국자동차공학회논문집
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• 제18권2호
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• pp.104-113
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• 2010

Domestic insurance claims were statistically investigated to analyze the elderly driver's accident patterns and injury types in side impact crashes. Medical treatment records and accident vehicle damage photos have been surveyed for 5,419 cases. The results of our statistical analysis showed that the thorax injury risk of the elderly drive group is 8.8 and 4.0 times higher than that of the young and middle age group respectively. Diagnosis showed that most thorax injuries were caused by rib fracture. The head injury risk of the elderly female driver group seemed to be higher than that of the younger female driver group, however, statistical test has not been conducted because of the lack of number of samples for elderly female accident.

• 정보처리학회 논문지
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• 제13권6호
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• pp.278-283
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• 2024

소프트웨어를 구현할 때 인간의 생명에 위협이 될 수 있는 부작용이 발생할 수 있습니다. 그러므로 소프트웨어가 안전에 미치는 영향을 측정하고 위협을 완화하고 예방하기 위한 대안을 만드는 것이 필요합니다. 위협 요소에 의한 영향도 측정을 위하여 소프트웨어 안전 진단을 수행하기 위한 구성요소가 필요하다. 본 논문은 소프트웨어의 위협 요인을 내부 요인과 외부 요인으로 분류하고 이러한 위협 요인의 영향을 정량적으로 시연하는 것을 목표로 합니다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.178-183
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• 2020

A series of experiments covering lowest three natural frequencies of rolling coupled pitching were conducted to investigate liquid sloshing with low liquid depth. The test results show that the most violent liquid sloshing in rolling and pitching is located in the vicinity of the first order natural frequency (f1). When the excitation frequency of rolling and pitching is located between 0.98f1 and 1.113f1, roof-bursting phenomenon of liquid appeared, and the maximum impact pressure is at 1.09f1. When the external excitation frequency is at 1.113f1, the number of sloshing shocks decreases sharply. Furthermore, the space distribution of the impact pressure on the left bulkhead and the top bulkhead was analyzed. It is concluded that with low liquid filling, the impact load is greater near the free surface and the top of tank, and the impact position of the side bulkhead increases with the increasing of the frequency near the resonant frequency.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.35-41
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• 2011

Recently, board level solder joint reliability performance of IC packages during drop impact becomes a great concern to semiconductor and electronic product manufacturers. The handheld electronic products are prone to being dropped during their useful service life because of their size and weight. The IC packages are susceptible to solder joint failures, induced by a combination of printed circuit board (PCB) bending and mechanical shock during impact. The board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this paper, applying the JEDEC (JESD22-B111) standard present a finite element modeling of the FBGA. The simulation results revealed that maximum stress was located at the outermost solder ball in the PCB or IC package side, which consisted well with the location of crack initiation observed in the failure analysis after drop reliability tests.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.233-239
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• 2003

측방 낙상에 관계된 상해는 노인들에 있어서 가장 치명적이고 빈번한 의료 문제를 야기한다. 측방 낙상에 의해 발생하는 심각한 결과 중 하나인, 고관절 골절은 넘어진 사람 중 약 1%에서만 발생하지만 고관절 골절은 신체장애, 사망 및 이에 관련된 의료비용의 상승 등을 초래한다. 본 연구에서는 측방 낙상시 고관절 골절에 큰 영향을 미치는 충돌 단계에서의 위험요소를 하중각도로 가정하여 이 요소에 대한 영향과 직립시와 비교하여 상대적인 위험도를 비교하고자 하였다. 실험 조건은 이전 연구자의 자료를 토대로 모사골반을 구성하였고, 이렇게 구성된 모사골반을 진자형 충격 시험기에 고정시키고 충격각도(0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$)를 변화시켜가며 대퇴골의 동적 거동을 조사하였다. 본 실험을 통하여 하중각도의 변화가 대퇴골 근위부에서의 변형에 영향을 주며, 다른 부위에 비해 대퇴골 경부에 상대적으로 큰 변형이 생겨 골절 가능성이 높다는 것을 확인하였다. 또한 낮은 충격속도에서도 직립 상태에 비해 큰 변형을 보였으며, 변형 분포의 차이도 나타내었다. 따라서 변형 크기의 차이뿐만 아니라 이러한 변형 분포의 차이도 고관절 골절 기전에 영향을 줄 것으로 사료된다.