• 한국농공학회지
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• 제23권1호
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• pp.86-102
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• 1981

The soil test data of 28 earth dams, scheduled to be constructed in Kore3, were selected for this study. The safety factors of their side slops were computed using Fellenius' "slice Method" by computer. The results summarized in this study are as follows; 1. Dam sections can be easily determined by fig.10 without a time consuming trial and error calculations of assumed sections. 2. For the economical design of earth dam sections, it was found that more cohesive soil was suitable for lower dams(dam height less than 25m) and soils with a higher friction angle was better for higher dams 3. In the case that used soil materials have the same Internal friction angle, side slope increase was almost same. 4. The relationship between side slope and friction angle was found as log.S=a tan ø+b (Fig. 7) 5. The relationship between side slope and cohesion (c) was also found as log. S=a c+b (Fig. 8) 6. The change of safety factors due to the change of central core materials was very little (Table-2) 7. The decrease of safety factors according to the unit weight increase of embankment materials was negligible. 8. In general the relationship between the wet unit weight and the saturated unit weight was r sat = (rt)$^2$+0. 140. This study will contribute to the determination of economic and safe planning and designing of earth dams, embankments and cutting side slopes.

• 한국유체기계학회 논문집
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• 제10권2호
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• pp.41-45
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• 2007

The shutoff unit was designed to provide rapid insertion of neutron absorbing material into the reactor core to shutdown the reactor quickly and also to withdraw the absorber slowly to avoid a log-rate trip. Four shutoff units were installed on the HANARO reactor but the half-core test facility was equipped with one shutoff unit. The reactor trip or shutdown is accomplished by four shutoff units by insertion of the shutoff rods. The shutoff rod(SOR) is actuated by a directly linked hydraulic cylinder on the reactor chimney, which is pressurized by a hydraulic pump. The rod is released to drop by gravity, when triplicate solenoid valves are de-energized to vent the cylinder. The hydraulic pump, pipe and air supply system are provided to be similar with the HANARO reactor. The shutoff rod drops for 647mm stroke within 1.13 seconds to shut down the reactor and it is slowly inserted to the full down position, 700mm, with a damping. We have conducted the drop test of the shutoff rod in order to show the performance and the structural integrity of operating system of the shutoff unit. The present paper deals with the 647mm drop time and the withdrawal time according to variation of the pool water temperature, the water level and the core flow.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.723-730
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• 2003

In general, well log and core data have been utilized for reservoir characterization. These well data can provide valuable information on reservoir properties with high vertical resolution at well locations. While the seismic surveys cover large areas of field but give only indirect features about reservoir properties. Therefore it is possible to estimate the reservoir properties guided by seismic data on entire area if a relationship of seismic data and well data can be defined. Seismic attributes calculated from seismic surveys contain the particular reservoir features, so that they should be extracted and used properly according to the purpose of study. The method to select the suitable seismic attributes among enormous ones is needed. The stepwise regression and fuzzy curve analysis based on fuzzy logics are used for selecting the best attributes. The relationship can be utilized to estimate reservoir properties derived from seismic attributes. This methodology is applied to a synthetic seismogram and a sonic log acquired from velocity model. Seismic attributes calculated from the seismic data are reflection strength, instantaneous phase, instantaneous frequency and pseudo sonic logging data as well as seismic trace. The fuzzy curve analysis is used for choosing the best seismic attributes compared to sonic log as well data, so that seismic trace, reflection strength, instantaneous frequency, and pseudo sonic logging data are selected. The relationship between the seismic attribute and well data is found out by the statistical regression method and estimates the reliable well data at a specific field location derived from only seismic attributes. For a future work in this study, the methodology should be checked an applicability of the real fields with more complex and various reservoir features.

• 한국인터넷방송통신학회논문지
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• 제22권4호
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• pp.17-22
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• 2022

최근 웹 서비스의 확산과 함께 데이터의 형태는 더욱 다양해지고 있다. 이미지, 동영상, 텍스트 등 데이터를 저장하는 형태 뿐 아니라 해당 데이터를 표현하는 속성 및 메타데이터 등도 개수 및 형태가 데이터 별로 상이하다. 이러한 비정형 데이터를 효율적으로 처리하기 위해 키밸류 스토어(Key-Value Store)의 사용이 확산되고 있다. LSM-Tree(Log Structured Merge Tree)는 다양한 상용 키밸류 스토어의 핵심 자료구조이다. LSM-Tree 는 모든 쓰기 및 삭제 연산을 로그 방식으로 기록함으로써 소량의 쓰기에 높은 성능을 제공하도록 최적화 되어 있다. 그러나 최근 유효성 만료 데이터의 대용량 삭제 연산이 LSM-Tree에 특수 키밸류 데이터로 삽입됨에 따라 사용자 요청의 지연시간 및 처리속도가 저하된다는 문제점이 있다. 본 논문은 기존 LSM-Tree의 장점을 모두 유지하면서도 삭제된 키를 주요 트리 구조에서 분리하여 상기 문제를 해결하는 Filtered LSM-Tree (FLSM-Tree)를 제안한다. 제안하는 기법은 상용 키밸류 저장소인 LevelDB에 구현되었으며 성능 평가에서 읽기 성능이 최대 47% 향상됨을 보인다.

• Journal of the Korean Wood Science and Technology
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• 제36권6호
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• pp.41-48
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• 2008

본 연구에서는 소나무 원목의 열처리 시 소요에너지에 대해 분석하였다. 소나무재선충 감염목에 대한 적절한 열처리는 소나무 재선충의 감염 확산을 막고, 감염목의 용재로서의 사용 가능성을 높인다. 본 연구에서는 병해충 감염목의 FAO 열처리 기준(International standards for phytosanitary measures (ISPM) No.15)에서 제시한 병해충 사멸 조건인 '목재 중심부 온도를 $56^{\circ}C$에서 30분 유지'를 위하여 소요되는 에너지를 평가하였다. 열처리에 소요되는 총 소요에너지는 초기 열처리 설정조건 도달에 필요한 처리기 벽체 가열, 처리기 내 공기 가열, 목재가열, 습도유지, 벽체 열손실로 구성되는 초기소요에너지와 열처리 설정조건 도달 이후의 열손실 보완 소요에너지, 즉 목재가열, 습도유지 및 처리기 벽체 열손실을 보완하기 위한 열손실 보완 에너지로 구분하였다. 단위시간당 초기소요에너지는 열처리 설정조건 도달 이후의 단위시간당 열손실 보완 에너지량보다 크며, 설정조건도달 이후의 단위시간 당 소요에너지는 거의 일정한 값을 가졌다. 시험결과 실험조건에 있어서 건조 온도와 더불어 상대습도가 매우 큰 영향을 미쳤으며 목재조건으로는 함수율 차이에 의해 변하는 밀도가 큰 영향을 미쳤다. 고온과 높은 상대습도 및 낮은 함수율, 즉 낮은 밀도가 열처리 속도를 증가시켰다. 이 연구를 통하여 소나무재의 열처리에 있어서 보다 효율적인 에너지 관리 방안을 마련할 수 있을 것으로 기대된다.

• 지구물리와물리탐사
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• 제26권3호
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• pp.138-149
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• 2023

해저지층의 지질특성을 파악하는 것은 지구과학 및 공학에서 중요한 과업으로 신뢰도 높은 탐사자료를 확보하는 경우 가능하다. 대한민국 남동해역 대한해협 천부 지층의 특성을 파악하기 위하여 심부 시추 지층물성 실험실 분석자료와 탄성파 탐사자료를 확보하였고, 이를 통합 분석하였다. 해저면 심도 200 m 하부까지 심부 시추코어를 회수하여 천부 지층 탄성파 음파속도 로그를 얻었고, 탄성파 단면과 대비하였다. 지층 음파속도 로그와 시간 영역 탄성파 자료는 시간-심도 변환을 수행하여 상관성이 15%에서 45%로 증가하였다. 탄성파 임피던스 초기모형을 설정하고 모형기반, 대역제한 및 산재쐐기 역산을 각각 수행하여 결과를 비교하였다. 도출된 탄성파 임피던스는 천부 지층 내부 퇴적층이 우세한 영역과 미고결 영역에서 변화되는 양상을 보였다. 본 연구에서 수행된 음파 임피던스 역산 기법은 향후 지층 물성분석 로그자료와 탄성파자료의 추가 확보 시 통합 분석을 위한 프레임워크로, 임피던스 분포 단면은 해저면 단층 규명과 천부가스 누출 탐지 등에 활용 가능하다. 국내 해양 심부 시추는 이산화탄소 저장 후보지 특성 파악과 자원 부존 평가 등을 목적으로 지속 추진되고 있으므로 통합 역산의 지구물리 분야 적용 가치가 높아질 것으로 기대된다.

• International Journal of Fluid Machinery and Systems
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• 제4권3호
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• pp.349-359
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• 2011

An unsteady numerical analysis has been carried out to study the strong impeller volute interaction of a centrifugal pump with six backward swept blades shrouded impeller. The numerical analysis is done by solving the three-dimensional Reynolds Averaged Navier-Stokes codes with standard k-${\varepsilon}$ two-equations turbulence model and wall regions are modeled with a scalable log-law wall function. The flow within the impeller passage is very smooth and following the curvature of the blade in stream-wise direction. However, the analysis shows that there is a recirculation zone near the leading edge even at design point. When the flow is discharged into volute casing circumferentially from the impeller outlet, the high velocity flow is severely distorted and formed a spiraling vortex flow within the volute casing. A spatial and temporal wake flow core development is captured dynamically and shows how the wake core diffuses. Near volute tongue region, the impeller/volute tongue strong interaction is observed based on the periodically fluctuating pressure at outlet. The results of existing analysis also proved that the pressure fluctuation periodically is due to the position of impeller blade relative to tongue.

• 천문학회지
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• 제24권1호
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• pp.95-105
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• 1991

In the presence of synchrotron losses, diffusion of an ensembel of relativistic particles in an intraculster medium is investigated. The diffusion coefficient in the medium is found to be constrained by $28.8\;{\pm}\;0.4\;{\leq}\;Log\;D\;{\leq}\;30.5\;{\pm}\;0.4\;cm^2s^{-1}$ with the energy dependency of $D_0{\varepsilon}^{\mu}$ of ${\mu}=0.4{\pm}0.2$ as the previous observations suggested. As an important implication of the result, the brightest head-tail radio source NGC 4869, whose radio tail structure is indicative for its orbit within the cluster core, is considered to be the major contributor of particles for the formation of the Coma radio halo.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.197-202
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• 2007

Most of seismic reflection prospecting assumes subsurface formation to be homogeneous media. These models are not capable of estimating small scale heterogeneity which is verified by well log data or drilling core. And those synthetic seismograms by homogeneous media are limited to explain various changes at field data. So we developed a inhomogeneous velocity model which can estimate inhomogeneity of background medium to implement numerical modeling from homogeneous medium and inhomogeneous medium on the model. Background medium using three autocorrelation functions in order to generate inhomogeneous velocity media was according to dominant wavelength of background medium and correlation length of random medium. And then we compared shot gathers. The results show that numerical modeling implemented at inhomogeneous medium depicts complex wave propagation of field data.

• 천문학논총
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• 제30권2호
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• pp.335-339
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• 2015

Using black hole masses which span $10^5-10^{10}M_{\odot}$, the distribution of galaxies in the (host spheroid stellar mass)-(black hole mass) diagram is shown to be strongly bent. While the core-$S{\acute{e}}rsic$ galaxies follow a near-linear relation, having a mean $M_{bh}/M_{sph}$ mass ratio of ~0.5%, the $S{\acute{e}}rsic$ galaxies follow a near-quadratic relation. This is not due to offset pseudobulges, but is instead an expected result arising from the long-known bend in the $M_{sph}{-{\sigma}}$ relation and a log-linear $M_{bh}{-{\sigma}}$ relation.