• 한국컴퓨터정보학회논문지
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• 제17권6호
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• pp.1-11
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• 2012

공정기술이 지속적으로 발달함에 따라 멀티코어 프로세서는 성능 향상이라는 장점과 함께 내부 연결망의 긴 지연 시간, 높은 전력 소모, 그리고 발열 현상 등의 문제점들을 내포하고 있다. 이와 같은 2차원 멀티코어 프로세서의 문제점들을 해결하기 위한 방안 중 하나로 3차원 멀티코어 프로세서 구조가 주목을 받고 있다. 3차원 멀티코어 프로세서는 TSV를 이용하여 수직으로 쌓은 여러 개의 레이어들을 연결함으로써 2차원 멀티코어 프로세서와 비교하여 배선 길이를 크게 줄일 수 있다. 하지만, 3차원 멀티코어 프로세서에서는 여러 개의 코어들이 수직으로 적층되므로 전력밀도가 증가하고, 이로 인해 발열문제가 발생하여 높은 냉각 비용과 함께 신뢰성에 부정적인 영향을 유발한다. 따라서 3차원 멀티코어 프로세서를 설계할 때에는 성능과 함께 온도를 반드시 고려하여야 한다. 본 논문에서는 캐쉬 구성에 따른 3차원 쿼드코어 프로세서의 온도를 상세히 분석하고, 이를 기반으로 발열문제를 해결하기 위해저온도 캐쉬 구성 방식을 제안하고자 한다. 실험결과, 명령어 캐쉬는 최고온도가 임계값보다 낮고 데이터 캐쉬는 많은 웨이를 가지는 구성을 적용할 때 최고온도가 임계값보다 높아짐을 알 수 있다. 또한, 본 논문에서 제안하는 캐쉬구성은 쿼드코어 프로세서를 사용하는 3차원 구조에서 캐쉬의 온도 감소에 효과적일 뿐만 아니라 성능 저하 또한 거의 없음을 알 수 있다.

• 동력기계공학회지
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• 제20권1호
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• pp.11-17
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• 2016

In this study, the simulation for performance comparison between basic single stage organic rankine cycle, multi stage reheater cycle and multi stage reheater & recuperator cycle was carried out. The multi stage reheater cycle and multi stage reheater & recuperator cycle was designed to improve the efficiency for organic rankine cycle using heat source from industrial waste heat and heat sink from deep ocean water. R245fa was selected as a refrigerant for the cycle and system efficiencies were simulated by the variation of the heat sink temperature and the cycle classification. Performance characteristics were simulated by using the Aspen HYSYS. It was confirmed that the system efficiency was decreased by the increase of heat sink temperature. These results can be considered to be applied as geo-ocean thermal energy conversion in where plenty of geothermal or ocean thermal resource exist.

• 한국해양공학회지
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• 제9권1호
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• pp.63-72
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• 1995

The crack which is discovered in various structures and machine elements is multi-cracks. Multi-cracks may cause serious problems because they grow individually, and coalesce into one and it leads to fracture. Fatigue tests have been carried out to study the growth and coalescence behavior of multi-surface-cracks initiated at the semicircular surface notch in type 304 stainless steel at elevated temperature. The results are as follows; When multi-surface-cracks are lying on the surface of material, the major surface crack has greater influence on the fatigue life than the subcracks. The aspect ratio of multi-surface-cracks is lower than that of single crack because of the interaction and coalescence of surface cracks. Crack growth shape turns to semiellipse from the semicircle notch. After coalescence, the surface crack length increases rapidly, and it leads to fracture. Further, the slope transition of Paris law was found in the da/dN-$\Delta$K$_1$ plots.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1362-1364
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• 2003

As non-isothermal mixed pixel is widely existed, the pixel-mean temperature cannot adequately represent the actual thermal state of land surface. The row crop was chosen as target to discuss the problem of component temperature retrieval. At first, the matrix model was found to express the thermal radiant directionality of the target. Then correlation of multi-angle infrared radiance was analyzed. In order to increase the retrieving accuracy, we chose the retrievable parameters and established the iterative method combining with inverse matrix to retrieve component temperature. It was proved by field experiment that the method could improve the retrieving accuracy and stability remarkably.

• Current Applied Physics
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• 제18권11호
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• pp.1436-1440
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• 2018

SiN and SiCN film production using plasma-enhanced atomic layer deposition (PE-ALD) is investigated in this study. A developed high-power and high-density multiple inductively coupled plasma (multi-ICP) source is used for a low temperature PE-ALD process. High plasma density and good uniformity are obtained by high power $N_2$ plasma discharge. Silicon nitride films are deposited on a 300-mm wafer using the PE-ALD method at low temperature. To analyze the quality of the SiN and SiCN films, the wet etch rate, refractive index, and growth rate of the thin films are measured. Experiments are performed by changing the applied power and the process temperature ($300-500^{\circ}C$).

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.49-53
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• 2005

This paper presents a multi-scale hybrid simulation for the design of a catalytic multi-tubular reactor with high performance. The multi-tubular reactor consists of shell and a large number of tubes in which various catalytic chemical reactions occur. To consider fluid dynamics in the shell-side and kinetics in the tube-side at the same time, commercial CFD package and process simulation tool are coupled. This hybrid approach allowed us to predict many kinds of meaningful results such as tube center temperature profile, heat transfer coefficients on the tube wall, temperature rise of cooling medium, pressure drop through shell and tube side, concentration profile of each chemical species along the tube, and so on., and to achieve the optimal reactor design.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.91-99
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• 2017

In order to meet the thermal performance analysis accuracy requirements of high density permanent magnet synchronous motor (PMSM), a method of multi physical domain coupling thermal analysis based on control circuit, electromagnetic and thermal is presented. The circuit, electromagnetic, fluid, temperature and other physical domain are integrated and the temperature rise calculation method that considers the harmonic loss on the frequency conversion control as well as the loss non-uniformly distributed and directly mapped to the temperature field is closer to the actual situation. The key is to obtain the motor parameters, the realization of the vector control circuit and the accurate calculation and mapping of the loss. Taking a 48 slots 8 poles high density PMSM as an example, the temperature rise distribution of the key components is simulated, and the experimental platform is built. The temperature of the key components of the prototype machine is tested, which is in agreement with the simulation results. The validity and accuracy of the multi physical domain coupling thermal analysis method are verified.

• 한국유체기계학회 논문집
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• 제16권5호
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• pp.18-23
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• 2013

Thermal aging test is performed to qualify the life time of equipment in thermally aged condition. Due to long life time more than 10 years like as in power plant, the equipment is subjected to the accelerated thermal aging condition which is able to shorten the long aging test period by increasing aging temperature. Normally, conservatism of thermal aging test causes to impose unbalanced and excessive thermal load on components of the equipment, and deformation and damage problems of the components. Additionally, temperature rise of each component through heat generation of the electric equipment leads to long-term problem of the test period. Multi-phase accelerating aging test is to perform thermal aging test in multiple aging conditions after dividing into groups with various components of equipment. The groups might be classified considering various factors such as activation energy, temperature rise, glass transition temperature and melting temperature. In this study, we verify that the multi-phase accelerating aging test method can reduce and equalize the thermal over load of the components and shorten aging test time.

• 소성∙가공
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• 제14권9호통권81호
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• pp.785-790
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• 2005

High-speed multi-pass wet wire drawing has become very common for production of high-carbon steel cord because of the increase in customer demand and production rates in real industrial fields. Although, the wet wire drawing process is performed at a high speed usually above 1000m/min, greater speed is required to improve productivity. However, in the high-carbon steel wire drawing process, the wire temperature rises greatly as the drawing speed increase. The excessive temperature rise makes the wire more brittle and finally leads to wire breakage. In this study, the variations in wire temperature during the multi-pass wet wire drawing process were investigated. A multi-pass wet wire drawing process with 21 passes, which is used to produce steel cord, was redesigned by considering the increase in temperature. Through a wet wire drawing experiment, it was possible to increase the maximum final drawing speed to 2000m/min.

• 대한기계학회논문집B
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• 제25권4호
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• pp.467-474
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• 2001

The mathematical model of a air-conditioning system is generally very complex and difficult to apply to controller design. In this paper, simple models applicable to the controller design are obtained by modeling the air-conditioning system by single-input single-output between compressor speed and indoor temperature, and by multi-input single-output between compressor speed, indoor fan speed and indoor temperature. Using these empirical models, model predictive control(MPC) technique was implemented for indoor temperature control of the air-conditioning system. It has been shown from various experiments that the indoor temperature control based on the MPC scheme yields reasonably good tracking performance with smooth changes in plant inputs. this multi-input multi-output MPC approach can be extended to multi air- conditioning systems where the conventional PID control scheme is very difficult to apply.