• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 춘계학술대회
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• pp.199-202
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• 1996

Artificial hearts are intended for use in patients with severe forms of heart disease for which no surgical repair is possible. The moving-actuator pump was developed to decrease the overall volume size of the electromechanical total artificial heart (TAH) by eliminating the occupied space of the fixed-actuator in the conventional pusher-plate type pump. In our pump, the actuator moves back and forth for alternative ejections of left and right ventricles. The problem of fitting the TAH to atrial remnants and arterial vessels could also be improved by circular or penduluous mot ion of the actuator instead of linear mot ion of the pusher-plate in the conventional pumps. We have evaluated two types of moving- actuator pump; one is a rolling cylinder type, and the other a pendulum type pump. In the rolling cylinder pump, frictional energy loss exists between the pump housing's guide bars and the actuator's end caps, while the bottom rack under the cylindrical actuator increases the height of the pump, the pump is therefor not implantable inside the small chest of human-sized animals with a body weight of less than 70kg. The new human type pump has a penduluous mot ion actuator to correct the above problems while maintaining the advantage of the moving- actuator's small total volume. The totally implantable TAH is composed of a blood pump, a control system and pheriperal equipments. The blood pump, which is constructed by a moving actuator, a right and left blood sac, and four artificial valves, is implanted in the thoracic. In 1988, the first implantation of the rolling cylinder TAH was performed into a female calf weighing 100kg, and the cal f recovered to the degree of voluntary standing and eat ing and survived to 100 hrs. We then survived two female sheep weighing about 63kg with the new human type TAH for three days.

• Journal of Biosystems Engineering
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• 제23권5호
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• pp.427-438
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• 1998

In Korea, rotary implements are mainly utilized in the tillage operation. The attitude control system for rolling phenominon of tractors, which in caused due to uneven ground surfaces and sinkage of tractor wheels, is one of the most important control systems in agricultural tractors. The attitude control system of a rotary implement, attached on tractors, was designed and fabricated in this study. The control system was largely composed of four main units; a setting unit, a detection unit, a controller and a hydraulic unit. The implement was controlled by control signals from a computer proportional to controlled errors, on/off action of two directional solenoide valve and lift cylinder on the right lift rod. Response characteristic experiments for the control system fabricated in this study were carried out indoors and outdoors. The results of experiments showed the response characteristics sufficient to use as the attitude control system of rotary implements for agricultural tractors.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1410-1415
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• 2000

This paper introduces the experimental analysis of the resonator in the rolling piston type compressor for air conditioner. The resonator located between cylinder and bearing is a major factor in the noise reduction of the rotary compressor. Several shapes for the resonator which can be built in the space limitations are derived. Then optimal resonator type for the noise reduction is determined by noise tests. 6 design parameters of the type are found and optimal level for each design factor is deduced from Taguchi method.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.82-89
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• 2005

This study was performed to investigate the behavior and spatial distribution of fuel mixtures with different wall angle and diameter of piston cavity in a DI gasoline engine. The spatial distribution of fuel mixtures after impingement of the spray against a piston cavity is one of the most important. factors for the stratification of fuel mixture. Thus, it is informative to understand in detail the behavior and spatial distribution of fuel mixtures after impingement in the cavity. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze the behavior and distribution of fuel mixtures inside cylinder by exciplex fluorescence method. The exciplex system of fluorobenzene/DEMA in non-fluorescing base fuel of hexane was employed. Cavity wall angle was defined as an exterior angle of piston cavity. Wall angles of the piston cavity were set to 30, 60 and 90 degrees, respectively. The spray impinges on the cavity and diffuses along the cavity wall by its momentum. In the case of 30 degrees, the rolling-up moved from the impinging location to the round and fuel-rich mixture distributed at periphery of cylinder. In the case of 60 and 90 degrees, the rolling-up recircurated in the cavity and fuel mixtures concentrated at center region. High concentrated fuel vapor phase was observed in the cavity with 90 degrees. From. present study, it was found that the desirable cavity wall angle with cavity diameter for stratification in a Dl gasoline engine was demonstrated.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1990년도 춘계학술대회
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• pp.1-6
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• 1990

A new version of moving actuator electromechanical total artificial heart was designed to improve total efficiency, durability, and fitting inside thoracic cavity. As compared with our present type of the rolling cylinder actuator, this new model has a pendulum-type actuator with reciprocating motion around the fixed circular path, connected through the gear mechanisms to the motor. By using this mechanism, the efficiency and durability could be improved by replacing sliding mechanism with rolling contact elements. Also, the height of the pump could be decreased from 9cm to 7cm with static stroke volume 65cc. With these improvements, we have implanted this new pump in human size animal (less than 70Kg weight).

• 대한조선학회논문집
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• 제43권6호
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• pp.667-674
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• 2006

Accurate prediction of ship dynamics, particularly roll motion, is very important in ship safety. In the past, empirical or vortex based methods were commonly used for the hydrodynamic roll damping predictions but they could not be applied to practical ship roll motion cause of limitations about geometries ad design conditions. Recently RANS-based techniques are developed for the practical ship motion analysis. In this study, RANS based roil analysis about a rectangular cylinder with WAVIS developed by MOERI/KORDI are performed and compared with the experimental data and other RANS results.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.711-729
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• 2018

This paper reports on the experimental investigations on the failure modes of ring-stiffened cylinder models subjected to external hydrostatic pressure. Nine models were welded from general structural steel. The shells were initially formed by cold-rolling, and flat-bar ring frames were welded to the shell. The hydrostatic pressure tests were conducted by using water as the medium in pressure chambers. The details of the preparation and main test were briefly explained. The investigation identified the consequence of the structural failure modes, including: shell yielding, local shell buckling between ring stiffeners, overall buckling of the shell together with the stiffeners, and interactive buckling mode combining local and overall buckling. In addition, the ultimate strengths were predicted by using existing design codes. Non-linear numerical computations were also conducted by employing the actual imperfection coordinates. Finally, accuracy and reliability of the predictions of design formulae and numerical were substantiated with the test results.

• Journal of Biosystems Engineering
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• 제27권2호
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• pp.79-88
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• 2002

This study was conducted to develop system for high speed rice transplanting machines. The control system includes a sensor detecting the tilt angle of the seedling bed, a micro-controller and a hydraulic system consisting of a double acting cylinder, a four-way three-position solenoid valve, a relief valve and a hydraulic pump. The levelling system shared the pump with the existing steering control, resulting in a tandem center circuit for the steering and levelling control systems. Using the input signal from the sensor, the micro-controller determined and generated the output signal to control the cylinder through the solenoid valve to keep the seedling bed always parallel to the water surface regardless of soil unevenness during the transplanting operations. Both an ON/OFF and a PWM control schemes were tested. When the flow rate was more than 1 ι/min in the ON/OFF control, the system showed unstable rolling. However, in the PWM control, the system worked stably although the flow rate was more than 1 ι/min. The PWM control showed a better performance when a large difference between the angle and the dead band of the control system occurred. The characteristics of tile system response to given tilt angles were predicted by a computer simulation. Both the ON/OFF and the PWM control systems worked well providing that the operating and waiting times were properly adjusted.

• Journal of the Korean Wood Science and Technology
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• 제39권4호
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• pp.333-343
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• 2011

백합나무(yellow poplar)는 기후변화의 주범인 이산화탄소의 흡수율이 매우 뛰어나고 오존흡수율도 뛰어나 저탄소 녹생성장 시대에 적합한 수종이다. 속성수인 백합나무는 구조용 부재로의 성능은 약간 부족하지만 가구재나 내장재, 합판용재 등 다양한 용도로 활용가능한 수종이다. 본 연구에서는 백합나무를 이용하여 대단면 스킨팀버를 개발하고 압축 성능을 평가하였으며 다양한 용도 개발을 위해 수치해석 모델을 개발하였다. 정각형 스킨팀버는 소재에 대해 56.3%의 잔존 강도를 보여서 우수한 성능을 나타내었으며 원통형 스킨팀버의 경우 잔존면적율이 25%임에도 불구하고 소재에 대해 50% 가까운 압축 성능을 나타내어 가구용 뿐만 아니라 대단면 재료로써 다양한 쓰임새가 가능함을 보여주었다. 정각형과 원통형 모두 Brooming or end rolling이 주요 파괴모드로 나타났으며 부분적으로 splitting 파괴 모드도 나타났다. 잔존면적률이 큰 정각형 스킨팀버의 압축성능이 원통형 스킨팀버보다 높게 나타났지만 두 집단간에 압축성능에 있어 통계적 유의성은 보이지 않아 사용자의 편의대로 혼용하여 활용 가능할 것으로 판단된다. 수치해석 모델은 실제 압축성능 실험과 상당히 유사한 결과를 보였다. 따라서 다양한 형태와 치수에 대한 수치해석 모델 적용을 통해 백합나무 스킨팀버의 다양한 용도 개발에 활용할 수 있을 것으로 기대된다.

• 한국소음진동공학회논문집
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• 제14권1호
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• pp.3-9
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• 2004

This paper introduces the experimental analysis of the resonator in the rolling piston type compressor for air conditioner. The resonator located between cylinder and hearing is a major factor in the noise reduction of the rotary compressor. Several shapes for the resonator which can be built in the space limitations are derived. Then optimal resonator type for the noise reduction is determined by noise tests. 6 design parameters of the type are found and optimal level for each design factor is deduced from Taguchi method.