• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1022-1026
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• 2013

Recently, the waste heat recovery technique using thermoelectric generator (TEG) in automotive engine has emerged to improve thermal efficiency in commercial vehicle. It is not difficult to recognize the numerous attempts that have been made to develop the TEG simulation model, but it is hard to find the model in conjunction with a particular heat engine system. In this study, 1-D commercial software AMESim was used to develop a computational model that can assess waste heat recovery from a diesel engine exhaust using TEG. The developed TEG simulation model can be used for evaluating the TEG performance of various types of TE module, and the diesel engine model can simulate any type of on and off-road diesel engines. The simulation results demonstrated that approximately 544.75W could be recovered from the engine exhaust and 40.4W could be directly converted into electricity using one TE module. The models developed in this study can be easily coupled with each other in the same computational program; thus, the models are expected to provide a viable tool for developing and optimizing a TEG waste heat recovery system in an automotive diesel engine.

• Journal of the Institute of Convergence Signal Processing
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• v.1 no.2
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• pp.169-176
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• 2000

Deadbeat property is well established in digital control system design in time domain. But in continuous time system, deadbeat is impossible because of it's ripples between sampling points inspite of designs using the related digital control system design theory. But several researchers suggested delay elements. A delay element is made from the concept of finite Laplace Transform. From some specifications such as internal model stability, physical realizations as well as finite time settling, unknown coefficents and poles in error transfer functions with delay elements can be calulted so as to satisfy these specifications. For the application to the real system, robustness property can be added. In this paper, error transfer function is specified with 1 delay element and robustness condition is considered additionally. As the criterion of the robustness, a weighted sensitive function's $H_{infty}$ norm is used. For the minimum value of the criterion, error transfer function's poles are calculated optimally. In this sense, optimal design of the continuous time deadbeat controller is obtained.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.2
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• pp.100-105
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• 2009

A watermarking for copyright protection of digital contents for broadcasting have to be made for a real-time system. In this paper, we propose a real-time video watermarking chip and system which is hardware based watermark embedding system of SD/HD video. Our chip is implemented by FPGA which is STRATIX device from ALTERA, and our system is implemented by GS1560A and GS1532 devices from GENNUM for HD/SD video signal processing. There was little visual artifact due to watermarking in subjective quality evaluation between the original video and the watermarked one. Embedded watermark was all extracted after a robustness test called natural video attacks such as A/D conversion and MPEG compression. Our implemented watermarking hardware system can be useful in movie production and broadcasting companies that requires real-time based copyright protection system.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.6
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• pp.273-282
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• 2016

Visualization tool can be divided by three components - data I/O, visual transformation and interactive rendering. In this paper, we present requirements of three major components on visualization tools for massive scientific dataset and propose strategies to develop the tool which satisfies those requirements. In particular, we present how to utilize open source softwares to efficiently realize our goal. Furthermore, we also study the way to combine several open source softwares which are separately made to produce a single visualization software and optimize it for realtime visualization of massiv espatio-temporal scientific dataset. Finally, we propose a distributed shared memory based scientific visualization tool which is called "GLOVE". We present a performance comparison among GLOVE and well known open source visualization tools such as ParaView and VisIt.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.171-176
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• 2006

In this paper, we develop energy efficient designs for the Fast Fourier Transform (FFT) on FPGAs. Architectures for FFT on FPGAs are designed by investigating and applying techniques for minimizing the energy dissipation. Architectural parmeters such as degrees of vertical and horizontal parallelism are identified and a design choices. We determine design trade-offs using high-level performance estimation to obtain energy-efficient designs. We implemented a set storage types as parameters, on Xilinx Vertex-II FPGA to verify the estimates. Our designs dissipate 57% to 78% less energy than the optimized designs from the Xilinx library. In terms of a comprehensive metric such as EAT (Energy-Area-Time), out designs offer performance improvements of 3-13x over the Xilinx designs.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2596-2604
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• 1997

There are two kinds of backends in ACK:code generator(full-fledged backend) and code expander(fast backend). Code generators generate target code using string pattern matching and code expanders generate target code using macro expansion. ACK translates EM to SPARC code using code expander. The corresponding SPARC code sequences for a EM code are generated and then push-pop optimization is performed. But, there is the problem of maintaining hybrid stack. And code expander is not considered to passes parameters of a procedure call through register windows. The purpose of this paper is to improve SPARC code quality. We suggest a method of SPARC cod generation using EM tree. Our method is divided into two phases:EM tree building phase and code expansion phase. The EM tree building phase creates the EM tree and code expansion phase translates it into SPARC code. EM tree is designed to pass parameters of a procedure call through register windows. To remove hybrid stack, we extract an additional information from EM code. We improved many disadvantages that arise from code expander in ACK.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.933-933
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• 2012

최근 들어 우리나라를 포함한 전 세계적으로 극심한 기후변화와 기상이변으로 집중호우에 의한 피해가 급증하고 있으며, 기상재해에 따른 강우-유출 현상에 관한 정확한 해석이 필요하게 되었다. 국내의 경우에도 1990년 중반부터 매년 국지적 집중호우나 이상호우로 인해 재산 및 인명피해가 속출하고 있다. 대상유역으로 선정한 우이천 유역 또한 강북구의 대표적인 상습침수지역으로 피해 받고 있는 상황이며, 이를 예방하기 위해 홍수범람도 작성, 재해지도 작성 등의 지리정보시스템 기법 및 각종 수해대책이 활발하게 진행되고 있지만 아직은 미비한 실정이다. 본 연구에서는 우이천 유역에 대한 강우-유출 해석을 위한 분포형 모형인 Vflo$^{TM}$의 적용성을 검토 분석하는 데에 의의를 두었다. 또한 각 격자크기별로 유출량의 변화를 타 모형과의 비교를 통하여 적정성을 검토하였다. 이를 위해 대상유역의 1:1000 수치지형도를 이용하여 50m, 100m, 150m, 200m의 DEM을 생성하였고 ArcGIS 프로그램의 Hydro툴을 이용하였다. DEM을 보간하기 전 총 세 곳의 Sink를 발견하여 조정한 후 Filling하였으며 수치지형도와 정밀토양도로부터 초기 입력자료를 생성한 후 ASCII 파일로 변환하여 분포형 모형에 적용하였다. 또한 VfloTM 를 통해 구성한 격자망을 실제 흐름 방향을 고려하여 최종 유출구로 흐를 수 있도록 격자망을 재구성하였으며, 강우의 공간적 분포 방법으로 Cokriging 기법을 사용하였다. 분석 결과 격자 크기가 작은 경우 오히려 첨두유량이 작게 산정되었는데 이는 배수계통의 변화 및 수치지형도와는 다른 지표면 특성으로 인한 것으로 사료된다. 또한 배수구역의 최적화 결과 전반적으로 실측치와 유사한 값을 나타내었으며, 타 모형과 비교한 결과 비슷하거나 조금 나은 결과를 보였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.133-133
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• 2010

3-5족 화합물 반도체를 이용한 집광형 삼중 접합 태양전지는 35% 이상의 광변환 효율로 주목을 받고 있다. 일반적으로 삼중 접합 태양전지는 넓은 영역대의 파장을 흡수하기 위해 밴드갭이 다른 InGaP, GaAs, Ge이 사용된다. 그 중 하부셀은 기계적 강도가 높고 장파장을 흡수할 수 있는 Ge이 사용되는데, p-type Ge 기판위에 III-V 결정막 성장 시 5족 원소가 확산되어 pn접합을 형성하게 된다. 이러한 구조를 가진 Ge 하부셀이 효율적으로 홀-전자 쌍을 형성하기 위해서는 두꺼운 베이스와 얇은 에미터 접합이 필요하다. InGaP의 phosphorus는 낮은 확산계수로 인해 GaAs의 arsenic에 비해 얇은 접합이 형성 가능하며, Ge표면 에칭효과가 더 적다는 장점이 있다. 이를 고려해 우리 연구그룹에서는 metalorganic chemical vapor depostion(MOCVD)을 이용하여 Ge기판위에 성장한 InGaP layer의 특성을 관찰해 보았다. <111>로 $6^{\circ}$ 기울어진 p-type Ge(100) 기판위에 MOCVD를 통해 InGaP layer를 형성하였고, 성장된 layer를 atomic force microscope(AFM)와 high-resolution x-ray diffraction(HRXRD)을 이용하여 표면형상, 조성, 응력상태 등을 각각 관찰하였다. 또한 phosphorus 확산에 의해 형성되는 도핑농도는 electrochemical capacitance-voltage(ECV)을 이용하여 관찰하였다. 성장된 Ge기판위의 InGaP layer의 경우 특징적으로 높이 50 nm, 밑변 길이 $1\;{\mu}m$의 경사진 표면을 관찰할 수 있었으며, 이러한 구조는 TMIn과 TMGa의 비율이 증가 할수록 감소하였다. 따라서 이러한 경사진 형태의 구조는 격자 불일치 때문인 것으로 판단된다. 추가적으로 V/III ratio의 최적화를 통해 1.3 nm의 표면 거칠기를 갖는 InGaP layer를 얻을 수 있었다. ECV를 통해 Ge 하부셀의 pn접합 형성을 관찰한 결과 약 160 nm에서 접합이 형성되는 것을 관찰할 수 있었다. 또한, 같은 성장 조건의 샘플을 1000 초 열처리 후에 접합깊이의 변화를 관찰한 결과 180 nm에서 접합이 관찰되었지만, GaAs의 arsenic에 의한 pn접합은 열처리 후에 그 깊이가 170 nm에서 300 nm로 증가 하였다. 따라서 삼중접합 태양전지의 제작 공정을 고려할 경우 phosphorus에 의한 접합 형성이 Ge 하부셀의 동작 특성에 유리할 것으로 판단된다.

• Journal of the military operations research society of Korea
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• v.33 no.1
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• pp.105-115
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• 2007

It is essential to give a fatal damage to the enemy force by using prompt and accurate fire in order to overcome the lack of artillery force. During the artillery fire operations, minimizing the firing time will secure the adapt ability in tactical operation. In this paper, we developed a mathematical model to schedule the artillery fire on the multiple targets to decrease total fire operation time. To design a program to describe a real firing situation, we consider many possible circumstances of changes such as commander's intention, firing constraints, target priority, and contingency plan to make a fire plan in an artillery unit. In order to work out the target sequencing problem, MIP is developed and the optimum solution is obtained by using ILOG OPL. If this analytical model is applied to a field artillery unit, it will improve the efficiency of the artillery fire force operations.

• Journal of KIISE
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• v.42 no.9
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• pp.1078-1089
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• 2015

In this paper, we propose the Min-hash Assisted Delta-compression Engine(MADE) to improve the lifetime of NAND flash-based storages at the device level. MADE effectively reduces the write traffic to NAND flash through the use of a novel delta compression scheme. The delta compression performance was optimized by introducing min-hash based LSH(Locality Sensitive Hash) and efficiently combining it with our delta compression method. We also developed a delta encoding technique that has functionality equivalent to deduplication and lossless compression. The results of our experiment show that MADE reduces the amount of data written on NAND flash by up to 90%, which is better than a simple combination of deduplication and lossless compression schemes by 12% on average.