• 한국운동역학회지
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• 제27권1호
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• pp.1-7
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• 2017

Objective: The purpose of this study was to analyze the relationship between ground reaction force (GRF) and attack time according to the position of hand segments during counter attack in Kendo. Method: The participants consisted of 10 kendo athletes (mean age: $21.50{\pm}1.95yr$, mean height: $175.58{\pm}5.02cm$, mean body weight: $70.96{\pm}9.47kg$) who performed standard head strikes (A) and counter attack with a preferred hand position of +10 cm (B), 0 cm (C), and -10 cm (D). One force-plate (AMTI-OR-7., USA) was used to collect GRF data at a sample rate of 1,000 Hz. The variables analyzed were the attack time, medial-lateral GRF, anterior-posterior GRF (AP GRF), peak vertical force (PVF), and loading rate. Results: The total attack time was shorter in types A and C than in types C and D. The AP GRF, PVF, and loading rate had significantly higher forces in types C and D than in types A and C. The attack time (bilateral and unilateral leg support and total) was positively correlated with the GRF variables (vertical GRF and loading rate) during the counter attack in Kendo (r = 0.779 [$R^2=0.607$], p < 0.001). Conclusion: The positions of the hand segments can be changed by various conditions of the opponent in Kendo competitions; however, the position preferred by an individual can promote the successful ratio of the counter attack.

• 대한기계학회논문집A
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• 제31권2호
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• pp.253-259
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• 2007

A new material tester has been developed to measure mechanical properties of thin film specimens at high temperature. It is useful for observing oxide film growth or local deformation on the surface, and for measuring creep strength. Main characteristics of the tester is as follows; First, high temperature is achieved by Joule heating generated by electricity passing through the specimen, which does not need to enclose the specimen by a furnace or a heating chamber. The exposed specimen enables one to observe the surface during the test. Because the overall size of the test rig is compact, the whole test rig can be placed in a chamber for environmental controlled tests. The loading device is from a level scales. Not only static load with fixed counter weight, but also variable load by moving counter weight controlled remotely can be applied for an ordinary creep test and creep-fatigue test, respectively. The detail of the construction, operation principle, and the specification are described. And also, an example of test result obtained using the creep tester is presented.

• 한국산학기술학회논문지
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• 제21권6호
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• pp.317-324
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• 2020

본 논문의 목적은 육상구조물과 비교하여 특수한 설치환경 및 목적을 가지고 있는 항만 외곽시설에 대한 보다 현실적인 침하 평가기준을 제안하는데 있다. 최근 신항만 개발 사업으로 축조된 외곽시설 특히 방파제는 먼 바다의 연약 지반에 설치되는 경우가 많다. 외곽시설은 자중으로 파랑 등의 외력에 직접 저항하는 구조물로 그 중량이 상당하여 연약 지반 위에 설치되는 경우에는 침하가 쉽게 발생하지만 구조물의 안정성 또는 기능성에 큰 영향을 주지 않는다. 하지만 현행의 안전점검 세부지침은 이러한 외곽시설의 특성을 고려하지 않은 침하 평가기준을 제시하고 있다. 이에 보다 현실적으로 외곽시설의 침하를 평가할 수 있는 간편식을 제안하였다. 간편식은 설계에서 고려한 허용잔류침하량과 침하 안정성평가 결과를 적용하여 최대 침하량을 선정하도록 하였다. 제안된 간편식의 적정성을 검증하기 위하여 최근 실시한 방파제 6개소의 측량 평가결과와 제안된 간편식 적용결과를 비교하였다. 간편식을 적용하였을 때, 기존 평가결과보다 침하 평가등급이 상향되었으며, 안정성평가 결과 적용 시에는 실제 측량결과와 거의 유사한 결과가 얻어짐을 확인할 수 있었다. 본 간편식을 활용하여 침하평가를 실시할 경우, 구조물에 안정성 및 기능수행 여부와는 무관하게 낮게 평가되는 기존의 침하평가를 보다 현실적으로 실시할 수 있을 것으로 기대된다.

• 대한임상독성학회지
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• 제1권1호
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• pp.43-46
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• 2003

Phenypropanolamine (PPA) is a sympathetic amine used in over-the-counter cold remedies and weight-control preparations. The side effects are hypertension, dysrhythmias, stroke, etc. The Food and Drug Administration (FDA) is taking steps to remove PPA from all drug products and has requested that all drug companies discontinue marketing products containg PPA due to high risk of hemorrhage stroke. But, in Korea now, patinets take products containg PPA with over the counter. We report here the case of PPA induced myocardial injury in a young woman who takes overdose for suicide.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.75-78
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• 1989

Insulation of P.E insulated cable under the field of high-voltage will be breakdown ultimately due to the degradation process called 'Treeing' which is generated in the insulation, so long as any counter-measure suppressing or eliminating it could not be provided. In this paper as a counter-measure Dodecyl Alcohol is mixed with P.E and Treeing under the temperature variation has been observed. Results show that the larger weight ratio of Dodecyl Alcohol is stronger the effect of suppressing Tree ing in the range from room temperature to 40$^{\circ}C$ and generated Treeing has been soon eliminated and it never again generated.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.263-266
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• 2008

We apply a closed die forging technology to a large crankshaft of which forging weight amounts to 850kg. 40ton counter-blow hammer forging machine is used. The forging process is optimized to reduce the forming load using finite element simulation. AFDEX 3D is used for forging simulation. The experiment is compared with finite element prediction and a good agreement is observed. The successful development of a large crankshaft by the closed die forging technology will contribute to opening a new area of closed-die forging application and to enhancing competitiveness of national machinery industries especially including ship part and power generation industries.

• 한국운동역학회지
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• 제22권1호
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• pp.25-34
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• 2012

The purpose of this study was to determine the effects of landing height on the lower extremity during a counter movement jump. Fourteen healthy male subjects (age: $27.00{\pm}2.94$ yr, height: $179.07{\pm}5.03$ cm, weight: $78.79{\pm}6.70$ kg) participated in this study. Each subject randomly performed three single-leg jumps after s single-leg drop landing (counter movement jump) on a force platform from a 20 cm and 30 cm platform. Paired t-test (SPSS 18.0; SPSS Inc., Chicago, IL) was performed to determine the difference in kinematics and kinetics according to the height. All significance levels were set at p<.05. The results were as follows. First, ankle and knee joint angles in the sagittal plane increased in response to increasing landing height. Second, ankle and knee joint angles in the frontal plane increased in response to increasing landing height. Third, there were no significant differences in the moment of each segment in the sagittal plane for the jumping height increment. Fourth, ankle eversion moment and knee valgus moment decreased but hip abduction moment increased for the jumping height increment. Fifth, Ankle and knee joint powers increased. In percentage contribution, the ankle joint increased but the knee and hip joints decreased at a greater height. Lastly, as jumping height increased, the power generation at the ankle joint increased. Our findings indicate that the height increment affect on the landing mechanism the might augment loads at the ankle and knee joints.

• International Journal of Aeronautical and Space Sciences
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• 제17권3호
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• pp.442-453
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• 2016

A significant source of vibration in helicopters is the main rotor system, and it is a technical challenge to reduce the vibration in order to ensure the comfort of crew and passengers. Several types of passive devices have been applied to conventional helicopters in order to reduce the vibration. In recent years, helicopter manufacturers have increasingly adopted active vibration control systems (AVCSs) due to their superior performance with lower weight compared with passive devices. AVCSs can also maintain their performance over aircraft configuration and flight condition changes. As part of the development of AVCS software for light civil helicopter (LCH) applications, a test bench is constructed and vibration control tests and simulations are performed in this study. The test bench, which represents the airframe, is excited using a pair of counter rotating force generators (CRFGs) and a multiple input single output (MISO) AVCS that consists of three accelerometer sensors and a pair of CRFGs; a filtered-x least mean square (LMS) algorithm is applied for the vibration reduction. First, the vibration control tests are performed with uniform sensor weights; then, the change in the control performance according to changes in the sensor weight is investigated and compared with the simulation results. It is found that the vibration control performance can be tuned through adjusting the weights of the three sensors, even if only one actuator is used.

• 한국산학기술학회논문지
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• 제16권8호
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• pp.5534-5540
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• 2015

철도 신호제어시스템에서 열차의 위치 및 점유 유무를 검지하기 위하여 궤도회로 이외에 axle counter적용 사례가 증가하고 있는 추세이다. 이에 본 연구에서는 열차검지 및 차축계수의 신뢰성을 높이기 위해 axle counter의 센서 방식을 지자기 센서 방식과 근접센서 방식을 비교하였으며, 그에 따른 차이점과 결과를 제시하였다. 또한, 정확한 차축검지를 위한 센서부의 취부조건 등을 고려한 설치에 대해 현장 경험을 기반으로 적용된 결과를 제시한다. 본 연구에서는 차축검지의 신뢰성 향상을 위해 센서의 위상차를 판단할 수 있도록 설계 변경한 결과 차축검지 기능뿐만 아니라 다양한 기능까지(열차의 방향검지, 열차속도검지 등) 수행할 수 있는 확장성을 확보하였다. 또한 열차의 종별, 무게 등의 특성에 종속되지 않았으며, 자체적으로 제작한 차축검지를 위한 모의차축 이송장치와 Test Bed를 구축하여 Lab. 테스트를 수행한 결과 350km/h의 속도에서도 차축 검지의 누락이 발생하지 않았음을 확인하였다. 이를 통해 열차의 검지뿐만 아니라 통과하는 열차의 속도와 편성 수, 선로전환기 통과 시 철사쇄정 조건 그리고 건널목 장치에도 적용할 수 있는 기반을 마련하였으며, 향후 철도 신호제어 시스템 전반에 확대 적용하게 되면 열차안전운행에 많은 기여를 할 것으로 판단된다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.108-114
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• 2000

The excitation forces from the periodical firing pressure in cylinder and the rotating crank mechanism cause lots of vibration problems in diesel engine. In this paper, the theoretical formulas for excitation forces are introduced and computational program for the optimization of crank angle is also developed to reduce the free moments in diesel engine. The computational results of 4-stroke in-line engine are applied to verify the reliability of the program.