• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.121-128
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• 2009

During a hypothetical high-pressure accident in a nuclear power plant (NPP), molten corium can be ejected through a breach of a reactor pressure vessel (RPV) and dispersed by a following jet of a high-pressure steam in the RPV. The dispersed corium is fragmented into smaller droplets in a reactor cavity of the NPP by the steam jet and released into other compartments of the NPP by a overpressure in the cavity. The fragments of the corium transfer thermal energy to the ambient air in the containment or interact chemically with steam and generate hydrogen which may be burnt in the containment. The thermal loads from the ejected molten corium on the containment which is called direct containment heating (DCH) can threaten the integrity of the containment. DCH in a NPP containment is related to many physical phenomena such as multi-phase hydrodynamics, thermodynamics and chemical process. In the evaluation of the DCH load, the melt dispersion rates depending on the RPV pressure are the most important parameter. Mostly, DCH was evaluated by using lumped-analysis codes with some correlations obtained from experiments for the dispersion rates. In this study, MC3D code was used to evaluate the dispersion rates in the APR1400 NPP during the high-pressure accidents. MC3D is a two-phase analysis code based on Eulerian four-fields for melt jet, melt droplets, gas and water. The dispersion rates of the corium melt depending on the RPV pressure were obtained from the MC3D analyses and the values specific to the APR1400 cavity geometry were compared to a currently available correlation.

• 해양환경안전학회지
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• 제22권1호
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• pp.123-128
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• 2016

프로펠러 표면의 생물 부착이 프로펠러 성능에 상당한 영향을 미치지만 프로펠러 표면 거칠기와 관련된 연구는 상대적으로 선체 표면에 비하여 많지 않다. 본 연구에서는 Schultz(2007)가 발표한 Granville's similarity-law scaling 절차에 기초하여 실선 7 m 크기의 탱커 프로펠러에 표면 부착물 상태가 서로 다른 3가지 경우를 고려하여 프로펠러 단독 효율의 감소의 변화를 Lifting surface code를 사용하여 수치적 계산을 수행하여 효율을 비교하였다. 본 논문에서의 결과는 표면 거칠기가 큰 석회질 부착물($k_s=0.001$)은 선박 설계 속도(J=0.5)에서 최대 15 %의 프로펠러 효율 감소를 보였음을 확인하였으며 이는 선박 운항 시 생물 부착에 의한 효율 감소에 대한 평가가 고려되어야 한다는 점을 나타내고 있다.

• 한국컴퓨터정보학회논문지
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• 제1권1호
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• pp.105-128
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• 1996

소프트웨어의 전체 비용 중에서 유지보수 비용이 절반 이강을 차지하고 있기 때문에, 이 비용을 줄이기 위한 도구가 필요하다. 유지보수를 위한 공학적인 기법들 중에서 역 공학은 원시 코드로부터 설계 정보를 추출하고 원시 코드를 다른 형태 혹은. 좀 더 추상화된 형태로 표현하는 과정이다. 본 논문에서는 역 공학 기법을 적용하여. 기존 COBOL 프로그램으로부터 프로그램들 간의 호출 관계. 프로그램 내의 논리 구조와 프로그램의 자료 흐름에 대한 정보를 추출하는 방법에 대해서 제안하고 회복된 설계 정보로부터 프로그램 구조조도와 모듈 구조도를 생성하는 방법에 대해서 제시한다. 원시 코드로부터 정확하게 생성된 구조도는 유지보수 자가 프로그램을 전체적으로 혹은, 구체적으로 이해하도록 지원하는 중요한 정의가 될 것이다. 또한. 유지보수 자가 프로그램을 재분석할 때 혹은 다른 유지보수 자들이 그 프로그램을 분석할 때. 명확하게 수정된 구조도는 유지보수 자들에게 프로그램을 더욱 쉽게 이해하도록 지원하게 될 것이다.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.128-133
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• 2012

본 논문에서는 기만신호의 영향을 분석하기 위하여 기만신호의 코드지연에 따른 코드 및 반송파 추적에 대한 결과를 분석하였다. 기만신호의 특성 및 방어 방법에 대한 조사를 통하여 현재 GPS 신호와 동기를 유지할 수 있는 중급기만을 고려하여 기만신호생성기를 이용하여 시뮬레이션을 수행하였다. 기만신호생성기에서 생성한 정상신호 및 기만신호가 합성된 신호를 소프트웨어 수신기를 통하여 신호처리를 수행하였다. 본 논문에서는 코드추적루프(DLL) 및 위상추적루프(PLL)의 출력값을 비교분석하여 기만신호의 영향을 파악하였으며 또한 기만신호 인가 시 잘못된 의사거리에 따른 항법해의 영향을 분석하였다. 결과적으로 기만신호의 영향은 신호추적 단계에서는 1칩 이내의 코드지연을 갖는 기만신호의 영향을 받으며 신호획득에서는 코드 지연에 상관없이 영향을 받는 것을 확인하였다.

• Structural Engineering and Mechanics
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• 제88권2호
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• pp.117-128
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• 2023

On February 6, 2023, Türkiye woke up with a strong ground motion felt in a wide geography. As a result of the Kahramanmaraş, Pazarcık and Elbistan earthquakes, which took place 9 hours apart, there was great destruction and loss of life. The 2023 Kahramanmaraş earthquakes occurred on active faults known to pose a high seismic hazard, but their effects were devastating. Seismic code spectra were investigated in Hatay, Adıyaman and Kahramanmaraş where destruction is high. The study mainly focuses on the investigation of ground motion parameters of 6 February Kahramanmaraş earthquakes and the correlation between ground motion parameters. In addition, earthquakes greater than Mw 5.0 that occurred in Türkiye were compared with certain seismic parameters. As in the strong ground motion studies, seismic energy parameters such as Arias intensity, characteristic intensity, cumulative absolute velocity and specific energy density were determined, especially considering the duration content of the earthquake. Based on the study, it was concluded that the structures were overloaded far beyond their normal design levels. This, coupled with significant vertical seismic components, is a contributing factor to the collapse of many buildings in the area. In the evaluation made on Arias intensity, much more energy (approximately ten times) emerged in Kahramanmaraş earthquakes compared to other Türkiye earthquakes. No good correlation was found between moment magnitude and peak ground accelerations, peak ground velocities, Arias intensities and ground motion durations in Türkiye earthquakes. Both high seismic components and long ground motion durations caused intense energy to be transferred to the structures. No strong correlation was found between ground motion durations and other seismic parameters. There is a strong positive correlation between PGA and seismic energy parameter AI. Kahramanmaraş earthquakes revealed that changes should be made in the Turkish seismic code to predict higher spectral acceleration values, especially in earthquake-prone regions in Türkiye.

• Asian-Australasian Journal of Animal Sciences
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• 제22권7호
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• pp.943-954
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• 2009

Diacylglycerol acyltransferase (DGAT) is a key enzyme that catalyzes the final and rate-limiting step of triglyceride synthesis. Both DGAT1 and DGAT2 genes code proteins with DGAT activity. Studies have shown DGAT1 polymorphisms associate with intramuscular fat deposition in beef cattle, but fewer associations between DGAT2 and beef cattle economic traits have been reported. The objective of this study was to investigate single nucleotide polymorphism (SNP) in intron3 of bovine DGAT2 and evaluate the associations of that with carcass, meat quality, and fat yield traits. Test animals were 157 commercial feedlot steers belonging to 3 Chinese native breeds (22 for Luxi, 24 for Jinnan, and 23 for Qinchuan), 3 cross populations (20 for Charolais${\times}$Fuzhou, 18 for Limousin ${\times}$Luxi, and 17 for Simmental${\times}$Jinan) and 1 Taurus pure breed population (16 Angus steers). In the current study, 15 SNP were discovered in intron3 and exon4 of DGAT2 at positions 65, 128, 178, 210, 241, 255, 270, 312, 328, 334, 365, 366, 371, 415, and 437 (named as their positions in PCR amplified fragments). Only 7 of them (128, 178, 241, 270, 312, 328, and 371) were analyzed, because SNP in three groups (65-128-255, 178-210-365 and 241-334-366) were in complete linkage disequilibrium within the group, and SNP 415 was a deletion and 437 was a null mutation. Frequencies for rare alleles in the 3 native breed populations were higher than in the 3 cross populations for 178 (p = 0.04), 270 (p = 0.001), 312 (p = 0.03) and 371 (p = 0.002). A general linear model was used to evaluate the associations between either SNP genotypes or allele substitutions and the measured traits. Results showed that SNP 270 had a significant association with the fat yield associated with kidney, pelvic cavity, heart, intestine, and stomach (KPHISY). Animals with genotype CC and CT for 270 had less (CC: -7.71${\pm}$3.3 kg and CT: -5.34${\pm}$2.5 kg) KPHISY than animals with genotype TT (p = 0.02). Allele C for 270 was associated with an increase of -4.26${\pm}$1.52 kg KPHISY (p = 0.006) and $-0.92{\pm}0.45%$ of retail cuts weight percentage (NMP, Retail cuts weight/slaughter body weight) (p = 0.045); allele G for 312 was associated with an increase of -5.45${\pm}$2.41 kg KPHISY (p = 0.026). An initial conclusion was that associations do exist between DGAT2 gene and carcass fat traits. Because of the small sample size of this study, it is proposed that further effort is required to validate these findings in larger populations.

• 대한전자공학회논문지SP
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• 제39권2호
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• pp.128-136
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• 2002

본 논문에서는 이동통신 단말기의 음성부호화기에 탑재할 수 있도록 TeakLite DSP Core를 이용한 음향반향제거기(Acoustic Echo Canceller)를 실시간으로 구현하였다. 음성부호화기에서 음향반향제거기가 사용할 수 있는 연산량의 제한때문에 적응필터는 NLMS(Normalized Least Mean Square) 알고리즘을 이용한 FIR 필터를 사용하였다. 먼저 음향반향제거기를 부동소수점 C-언어로 구현한 다음 고정소수점 시뮬레이션을 통하여 고정소수점 연산으로 바꾸었다. 그리고 고정소수점 연산 결과를 기반으로 어셈블리 언어로 프로그램을 작성하고 최적화 과정을 거쳐 실시간으로 동작하도록 하였다. 최종적으로 구현된 반향제거기는 프로그램 메모리가 624 words이고 데이터 메모리는 811 words이었다. 샘플링 주파수를 8 ㎑로 하였을 때, 32 msec의 반향경로 지연시간에 해당되는 256 차수의 필터를 이용한 경우에는 14.12 MIPS의 연산량을, 16 msec의 반향경로 지연시간에 해당되는 128 차수의 필터를 이용한 경우에는 9.00 MIPS의 연산량을 필요로 하였다.

• Journal of information and communication convergence engineering
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• 제1권3호
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• pp.123-128
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• 2003

This paper has addressed the implementation of the single rate Rate Adaptive Shaper(srRAS) described in RFC2963. This shaper has been proposed to use at the ingress of differentiated services networks providing Assured Forwarding Per Hop Behavior (AFPHB). srRAS is typically used in conjunction with single rate Three Color Marker(srTCM) described in RFC2697. srRAS itself is the tail-drop FIFO that is drained at a variable rate, and srTCM is the marker with metering function. G-srRAS is the same as srRAS except that RAS receives the green token state information from the downstream srTCM to avoid delaying a packet in RAS although there are sufficient tokens available to color the packet green. In this paper, we have addressed the algorithm and the architecture of srRAS, and the scheme to implement srRAS using VHDL(Very high-speed integrated circuit Hardware Description Language) and its related tools.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권3호
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• pp.117-128
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• 2002

This paper describes the smoke filling process of a fire field model based on a self-deve-loped SMEP (Smoke Movement Estimating Program) code to the simulation of fire induced flows in the two types of atrium space containing a ceiling heat flux. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k-$\varepsilon$ turbulence model with buoyancy production term. Also it solves the radiation equation using the discrete ordinates method. Compressibility is assumed and the perfect gas law is used. Comparison of the calculated upper-layer average tempera-ture and smoke layer clear height with the zone models has shown reasonable agreement. The zone models used are the CFAST and the NBTC one-room. For atrium fires with ceiling glass the ceiling heat flux by solar heat causes a high smoke temperature near the ceiling. However, it has no effect on the smoke movement such as the smoke layer clear heights that are important in fire safety. In conclusion, the smoke layer clear heights that are important in evacuation activity except the early of a fire were not as sensitive as the smoke layer tem-perature to the nature of ceiling heat flux condition. Thus, a fire sensor in atrium with ceiling glass has to consider these phenomena.

• 천문학논총
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• 제19권1호
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• pp.77-81
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• 2004

A high performance computing cluster for astronomical computations has been built at Korea Astronomy Observatory. The 64 node cluster interconnected with Gigabit Ethernet is composed of 128 Intel Xeon processors, 160 GB memory, 6 TB global storage space, and an LTO (Linear Tape-Open) tape library. The cluster was installed and has been managed with the Open Source Cluster Application Resource (OSCAR) framework. Its performance for parallel computations was measured with a three-dimensional hydrodynamic code and showed quite a good scalability as the number of computational cells increases. The cluster has already been utilized for several computational research projects, some of which resulted in a few publications, even though its full operation time is less than one year. As a major resource of the $K^*Grid$ testbed, the cluster has been used for Grid computations, too.