• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.1
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• pp.1-9
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• 1984

In the utilization of solar energy most often a flat solar collector is used for solar heating, system. Since solar energy is absorbed through this solar collector, it is considered to be a most important part in the whole solar heating system. The purpose of the present investigation is to evaluate the influence of varying design parameters for thermal performances of flat-plate solar collector. By analysing these parameters, optimum design of solar collector would become possible. Specification of the existing solar collector are utilized in calculation as a starting point. Analysis is carried out numerically for "Unit Solar Collector" which is composed of fin and tube. Among design parameters. such parameters as mass flow rate per unit area, tube spacing and fin thickness are selected as variables in the computer simulation model. Results are presented for thermal performances of flat-plate solar collector for each important design parameters, so that predictions become possible through numerical analysis without performing experiments whenever it is required. required.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.71-76
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• 2003

A numerical simulation of selective catalytic reduction (SCR) for NO with $NH_3$ is conducted over the $V_2O_5/TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts. The governing $NH_3$ and NO transport equations are considered by using the time-dependent FCT (Flux-Corrected Transport) algorithm. After a validating simulation for $NH_3$ step feed and shut-off experiments is analyzed, transient behavior of $NH_3$ and NO concentration in a SCR catalyst is investigated by changing such parameters as inflow $NH_3$ concentration, temperature of the catalyst, and $NH_3$/NOx ratios.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.584-587
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• 2007

PCS를 비롯하여 WLAN, DMB, W-CDMA, UWB 등의 무선통신 서비스가 증가함에 따라 안테나 동작 대역폭의 광대역화가 더욱 요구된다. 1/4 파장 선형 모노폴 안테나는 구조가 간단하고 전방향성을 갖는 복사특성으로 인하여 가장 널리 사용되는 안테나 중의 하나이다. 모노폴 안테나의 광대역화를 위해서 일반적으로 원통의 직경을 증가시키는 방법을 사용하지만, 평면 모노폴에 적용된 스텝 기법을 적용하여 광대역 특성을 얻을 수 있다. 그러나 스텝 모노폴 자체는 광대역 특성을 나타내지 않으며, 접지면에서도 일정 형태의 스텝 돌출부위가 필요하게 된다. 본 논문에서는 그라운드면의 볼록 계단 구조가 모노폴 안테나의 대역 특성에 미치는 영향을 분석하여 최적의 안테나 급전구조를 도출하고자 한다. 결과의 검증을 위해서 소프트웨어 시물레이션 및 측정결과를 제시한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.584-590
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• 1984

This study is to develop a program, with which the motion of the system can be simulated in view of kinematics and dynamics, and then evaluate functional capabilities of many robots in order to select the most suitable one for any given working conditions. According to the theory of Denavit & Hartenberg, rectangular coordinate is set at each joint in the robot of six joints, as this one is the major concern, and transformation matrices are derived between any two coordinates. The necessary displacement of each joint for executing a given a work is obtained from the position and posture transformation and the in-stantaneous velocity of the joint is got from given velocity distribution of the path. The necessary torque of each joint is finally calculated by Newton-Euler Method. This simulation program is applied to a robot with six rotational joints, Rotational angle and torque to time which has a given motion trajectory are figured and also torque to r.p.m.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.292-297
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• 2003

A stochastic approach has been presented for superplastic deformation of Ti-6AJ-4V alloy, and probability function are used to heterogeneous phase distributions. The experimentally observed spatial correlation function are developed, and microstructural evolutions together with superplastic deformation behavior have investigated by means of the probability function. The result have shown that the probability varies approximately linearly with separation with distance, and significant deformation enhanced probability changes during the deformation. The stress-strain behavior with the evolutions of probability function can be correctly predicted by the model. The finite clement implementation using Monte Carlo simulation associated with phase re-distributions shows that better agreement with experimental data of failure strain on the test specimen.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.693-698
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• 2003

The application of object-oriented modeling to develop a powertrain performance simulation program, called P-DYN, is introduced. Powertrain components, such as the engine, transmission, shaft, clutch are modeled as classes which have data and method by using object-oriented modeling methodology. P-DYN, a performance simulation program, based on the object-oriented modeling is made in C++. One powertrain example is simulated through the P-DYN. It is expected that the simulation program or individual class constructed in this paper would be useful for automotive engineers in predicting the performance of powertrains and developing a simulation program.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.65-71
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• 2003

To maximize the storage density in a localized hologram recording method, each hologram should be recorded as close as possible to its neighboring holograms. In this case, the reference beams used to record two adjacent holograms may overlap in spatial multiplexing. Through simulations and experiments, we show that there exists an optimal reference beam size to minimize the overlap for a given shifting distance of the reference beams in spatial multiplexing. Thus the advantages of the localized hologram recording method can be minimally sacrificed while the storage density is increased.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.74-76
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• 2008

최근 BLDC 모터는 널리 사용되고 있지만, 불필요한 코깅 토크가 발생된다. 본 논문에서는 BLDC 모터의 코깅 토크 감소 방법을 설계하고 실험 하였다. 이론을 바탕으로 한 이 방법은 모터의 Magnet을 움직여 고주파성분을 제거하여 코깅 토크를 감소시키는 방법이다. 4극 24슬롯 BLDC 모터를 이용하여 Flux2D로 시물레이션 하고 계산 결과를 얻었다.

• Proceedings of the ESK Conference
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• 1993.04a
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• pp.69-77
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• 1993

원자력분야에서 인적요인의 검토, 평가, 개선의 필요성이 강조되고 있으나 인간공학 응용을 위한 기반기술의 미비로 인해 명시적 수단을 제공하지 못하고 있다. 본 연구는 인간공학적 응용수단의 하나인 운전원 모형을 개발하 기위하여, 그 첫 단계로 모형개발의 방향을 모색하였다. 원자력분야의 응용에 적합한 개발방향을 설정하기 위 하여, 첫째 모형화되어야 할 주요 운전원의 특성을 파악하였으며, 둘째 다른 응용분야와 원자력분야에서의 주요 모형개발사례를 조사분석하고, 셋째 모형화 방법론과 구현기법을 검토하였다. 그 결과, 중앙제어실 운전원을 대상 으로 진단(diagnosis)등 주요 직무수행에 나타나는 의사결정의 전략과 특성을 체계화하여 인지심리학적 기반이 확고한 개념모형(conceptual model)을 개발하고, 이를 전문가 시스템 개발도구(tool)에 의해 구체적인 소프트웨어로 구현함으 로써, 인적요인의 검토, 평가, 개선 등에 직접 활용가능한 시물레이션 수단(simulation tool)을 확보한다는 추진전략을 수립하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.2
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• pp.54-63
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• 1981

An ultrasonic imaging system with fan reflection mode time of fight is developed and its performance has been examined by system implementation. Experimental results obtained indicafe potential of the method for tomographic imaging. The basic concept of this method is reconstruction of reflectivity with reflection data collected in fan mode using a new "arbitrary ray" reconstruction algorithm. Computer simulations as well as experimental results are presented.presented.