• Journal of the Korea Society for Simulation
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• v.22 no.3
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• pp.81-87
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• 2013

This paper is about study how to decrese surge pressure that is occurred in excavator driving motor. We used computer simulation program SimulationX. It is also about the way finding design problem and approaching a solution through interpreting shape design sensitivity analysis. Programmes are below. First of all, finding shape fault by analyzing dynamic behavior of valves installed in hydraulic driving motor which is designed now. And drawing variable which is considered sensitive to improve dynamic efficiency among a lot of shape variables. Then, targeting that variable and examining dynamic efficiency stabilization tendency with controlling it. Finally, suggesting the most effective tuning method through variable combination as there are a lot of sensitive variables.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.268-268
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• 2016

우리가 알고 있는 북한 수리 시설물들의 용량은 대부분 일제 시기의 자료나 북한과 국제기구에서 발행하는 간행물에 근거하고 있다. 그러나 실제 발전용량 및 저수용량은 기존 자료와는 차이를 보이는 것으로 조사되고 있다. 본 연구에서는 북한 수리 시설물들의 저수량을 재산정하고, 이를 추후 각종 조사 및 분석에 활용하고자 하였다. 이를 위해 해당 지역의 위성자료와 DEM(Digital Elevation Model) 자료를 수집 및 활용하였다. 북한지역의 DEM은 격자 크기 $100m{\times}100m$로 분석하였다. 북한 수리 시설물의 저수량 파악을 위해 Global Mapper 프로그램을 이용하였으며, DEM과 위성자료를 입력해서 분석하였다. 선정된 수리 시설물에 대한 유역경계를 설정하고, 수면표고별 저수면적 및 저수량을 산정하였다. 이를 통해 Hypsometric Curve와 수면표고-저수면적-저수량 곡선을 작성하였으며, 해당 시설물의 저수량을 평가하였다. 이러한 방법으로 북한 금야강발전소의 저수량을 산정한 결과 약 19억7천만$m^3$으로 나타났다. 금야강발전소의 높이는 약 90m, 발전용량은 18만kW 정도이고, 우리나라 소양강댐의 높이가 123m, 발전용량이 20만kW일때 총 저수용량이 29억$m^3$인 점을 감안하면 적절한 산정결과인 것으로 판단되었다. 본 연구의 성과는 추후 북한의 분석 가능한 수력발전소들의 실제 저수용량을 계산하며, 주요 지점별로 개발 가능한 저수량을 산정해서 각종 개발사업 계획 수립에 활용할 수 있을 것으로 기대된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.936-944
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• 2003

In this paper, we propose an AND/XOR-based technology mapping method for field programmable gate arrays (FPGAs). Due to the fixed size of the programmable blocks in an FPGA, decomposing a circuit into sub-circuits with appropriate number of inputs can achieve excellent implementation efficiency. Specifically, the proposed technology mapping method is based on Davio expansion theorem to decompose a given Boolean circuit. The AND/XOR nature of the proposed method allows it to operate on XOR intensive circuits, such as error detecting/correcting, data encryption/decryption, and arithmetic circuits, efficiently. We conduct experiments using MCNC benchmark circuits. When using the proposed approach, the number of CLBs (configurable logic blocks) is reduced by 67.6% (compared to speed-optimized results) and 57.7% (compared to area-optimized results), total equivalent gate counts are reduced by 65.5 %, maximum combinational path delay is reduced by 56.7 %, and maximum net delay is reduced by 80.5 % compared to conventional methods.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.58-64
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• 2014

Hydraulic dual chamber, as the simulator for a dual pulse rocket motor, was tested by a high pressure device with various orifice-hole size being applied. Pressure difference occurs between 1st chamber and 2nd chamber depending on area ratio of the orifice to nozzle throat. Studying a design configuration of the orifice is essential to the motor development because pressure difference severely affects the rocket motor performance. It is noticed in this study that energy dissipation is caused by the vortex flow originating from the orifice as the 2nd chamber is operated. The flow field is simulated by a commercial computational fluid dynamics program, ANSYS FLUENT V14.5.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.4
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• pp.310-318
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• 2015

In this paper, dual-port eFuse OTP (one-time programmable) memory cells with smaller cell sizes are used, a single VREF (reference voltage) is used in the designed eFuse OTP IP (intellectual property), and a BL (bit-line) sensing circuit using a S/A (sense amplifier) based D F/F is proposed. With this proposed sensing technique, the read current can be reduced to 3.887mA from 6.399mA. In addition, the sensing resistances of a programmed eFuse cell in the program-verify-read and read mode are also reduced to $9k{\Omega}$ and $5k{\Omega}$ due to the analog sensing. The layout size of the designed 32-bit eFuse OTP memory is $187.845{\mu}m{\times}113.180{\mu}m$ ($=0.0213{\mu}m2$), which is confirmed to be a small-area implementation.

• The Journal of the Korea Contents Association
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• v.9 no.10
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• pp.186-195
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• 2009

This research is intended to provide basal material on institute composition of nursing homes that will be built in the near future. According to the result, five of the passages are central type, one of them is extensive type, and the other is group type. Secondly, in living space bedroom area is widest, and both sizes of bedroom system and floor heating system are the same. Thirdly, the sizes of clinic room and physical therapy room are similarly widest in medical space, and people use physical therapy room most frequently. Fourth, dining room and kitchen area are widest in public space, and it is hard to move to program room. Fifth, office area is widest in superintendent space, and it is located near lobby on the first floor. Sixth, the dimension per individual doesn't reach the standard of bedroom size per individual. Seventh, in each space, the rate of whole dimension of living space is highest.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1104-1110
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• 2011

The conventional semiconductor equipment has adopted SRAM module as the test pattern memory, which has a simple design and does not require refreshing. However, SRAM has its disadvantages as it takes up more space as its capacity becomes larger, making it difficult to meet the requirements of large memories and compact size. if DRAM is adopted as the semiconductor inspection equipment, it takes up less space and costs less than SRAM. However, DRAM is also disadvantageous because it requires the memory cell refresh, which is not suitable for the semiconductor examination equipments that require correct timing. Therefore, In this paper, we will proposed an algorithm for punctuality guarantee of memory-free inspection equipment using DDR2 SDRAM. And we will Developed memory controller using punctuality guarantee algorithm. As the results, show that when we adopt the DDR2 SDRAM, we can get the benefits of saving 13.5 times and 5.3 times in cost and space, respectively, compared to the SRAM.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1082-1086
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• 2008

소양강댐 유역에서 몇 년간 계속되는 고탁수 문제가 좀처럼 개선되고 있지 않는 실정이다. 탁수발생의 원인은 여러 가지가 있지만 농경지를 중심으로 유입되는 토양유실이 가장 직접적인 원인으로 지적되고 있다. 특히, 고랭지 농경지에서 소득 작물에 대한 연작피해 경감, 작물의 생산성 향상과 농민들의 소득 증대와 연관되어 무분별하게 농경지에 행해진 객토와 농약 및 비료는 수질 악화의 매우 큰 영향을 미치고 있다. 이러한 문제로 인하여, 토양유실량 추정을 위한 여러 모형들이 개발되었다. 이 중, SWAT 모형은 미국 농무성의 농업연구소에서 개발된 유역단위 모형으로 대규모의 복잡한 유역에서 장기간에 걸친 다양한 종류의 토양과 토지이용 및 토지관리 상태에 따른 수문과 유사 및 농업화학물질의 거동에 대하여 예측하기 위해 개발된 모형이다. 이 SWAT모형은 유역내 수문 및 유사 모의시, DEM을 기반으로 유역 평균경사도를 이용하여 경사도-경사장 관계식 산정 경사장을 유역내 모든 수문학적 반응단위 (HRU: Hydrologic Response Unit)의 동일하게 적용한다. 이는 SWAT 모의 유사량과 실측 자료에 있어서 큰 차이를 초래할 수 있다. 따라서 본 연구에서는 해안면 지역의 모든 농경지에 대해 강원발전연구원에서 전수 조사한 실측 경사장 및 경사도 자료를 반영할 수 있도록 소유역내 모든 HRU에 면적 가중 경사도/경사장을 할당해 주는 프로그램을 개발하여 준분포 모형인 SWAT의 단점을 극복하였다. 그 결과 유출량의 경우 면적 가중 실측경사장 및 경사도를 적용 유무에 따라 월 평균유량 3,951,537 m3/month, 3,953,947 m3/month로 2,410 m3/month의 큰 차이를 보이지 않았지만, 유사량의 경우 면적 가중 실측경사장 및 경사도 적용 하였을 경우 10,826 ton/month 이고, 기존 SWAT 예측 유사량은 월평균 3,642 ton/month으로 7,184 ton/month (66.4 % 차이) 큰 차이를 보였다. 이러한 결과는 SWAT 모형 적용시 경사장 및 경사도 산정에 따라, 유사량이 과소 또는 과대 평가 될 수 있음을 보여준다.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.4
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• pp.129-143
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• 2014

The purpose of this study is to evaluate flooding vulnerability considering spatial characteristics focused on Changwon-si, Gyeongsangnam-do. Assessment Factors are water cycle area ratio, surface runoff, and precipitation. And construction of assessment factors and vulnerability was analyzed by GIS program. Water cycle ratio and surface runoff were vulnerable in urban area. Precipitation was often distributed in agriculture of the northern region. Results of flooding vulnerability were low in agriculture and forest of the northern region. In contrast, urban area was high because there has covered impervious land cover. Analytical results of flooding vulnerability density using hotspot spatial cluster analysis were high in urban area. And these areas were situated in down stream so flooding were generated. Therefore, flooding vulnerability assessment of this study can help for selecting construction sites of pervious land cover and rainwater management facilities in urban and environmental planning.

• Composites Research
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• v.23 no.2
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• pp.17-23
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• 2010

The stealth technology can increase the survivability of aircrafts or warships and enhance the capability of mission completion in hostile territory. The purpose of this paper is to present the low observable structure with curved surfaces made by fiber-reinforced composites and to show the possibility of developing omnidirectional stealth platforms for military applications. In this study, we developed a radar absorbing structures(RAS) based on a circuit analog absorber to reduce the radar cross section(RCS) of an object with curved surfaces. Firstly, the RAS with a periodic square patterned conducting polymer layer was designed and simulated using a commercial 3-D electromagnetic field analysis program. Secondly, the designed semi-cylindrical structure with low RCS was fabricated using fiber-reinforced composites and conducting polymer. To make the periodic pattern layer, acts as resistive sheet, the intrinsic conducting polymer paste containing PEDOT with a polyurethane binder was used. Finally, the radar cross section was measured to evaluate the radar absorbing performances of the fabricated RAS by the compact range facility in POSTECH.