• KIEAE Journal
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• 제6권1호
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• pp.33-38
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• 2006

The purpose of this study is to investigate the concentration of sea-salt distribution giving great characteristic environmentally. Therefore the field measurement was conducted to target high-rise apartments constructing in reclaimed land of Busan and measured the concentration of sea-salt by means of distance and height of high-rise apartments from coast. The results of this study were as follows ; 1) The more a horizontal distance is far from coast, the more concentration sea-salt become low. But this study can not draw conclusion exactly as differ from a tendency of the thing close to the coast and the land. 2) In the near seaside, No.132 apartment accords existing research result that in difference of the concentration of sea-salt by height, the more height is high, the more that is high. But in seaside, No.117 apartment of middle point appears that the upper story and the lower story than middle story. Once more, in inland, No.132 apartment and No.117 apartment tend toward opposite it of the seaside. The reason that the result of this measurement and existing study is not agreement is thought that it occurs to turbulent flow between apartments by construction of high-rise apartments group.

• 대한기계학회논문집
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• 제9권4호
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• pp.403-413
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• 1985

본 논문에서는 수직벽 하류에 형성되는 박이 전단층의 발전과 재부착 그리고 재발전 경계층에 대해 평균 속도, 벽면의 압력 분포, 난류 강도, 레이놀즈 전단 압력 및 아직 수직벽에 대해서는 보고된바 없는 난류 떨림 속도 성분들의 3승곱 통계치를 측정하여 난류 구조의 변화를 분석하고 이를 수치적 계산 모델개발의 자 료로 제공하고자 함이 이 연구의 목적이다.

• 천문학회보
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• 제44권1호
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• pp.62.2-62.2
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• 2019

The ADF-S (AKARI Deep Field - South) toward South Ecliptic Pole is one of the deep survey fields designed for the study of Extragalactic Background Light (EBL). The deep extragalactic survey was initiated by AKARI far-infrared deep observations. Other space missions (e.g., Euclid, NISS, SPHEREx) will perform the deep observations in the ADF-S. Based upon the recent optical survey with KMTNet, we can identify the optical counterparts for dusty star-forming galaxies such as ULIRG, DOG, SMG. Among them, the Dust-Obscured Galaxies (hereafter DOGs with f(24um)/f(R) > 1,000) in the heavily obscured system are expected to play an important role in the formation of most massive galaxies. We have newly discovered ~100 DOGs in ~12 sq. deg. of the ADF-S from our optical survey with KMTNet. We also confirmed that some of DOGs host the most luminous AGN for their black hole masses through the near-infrared spectroscopic follow-ups. Here, we report the properties of high-z hyperluminous DOGs in the ADF-S.

• 천문학회보
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• 제39권2호
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• pp.51.2-51.2
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• 2014

Ultra faint dwarf galaxies (UFDs) are larger but fainter than globular clusters, being the faintest galaxies in the universe. They have been found only in the Local Group. We report the discovery of an UFD in the intracluster field of the Virgo cluster (Virgo UFD1). It is located near the core of Virgo cluster, and far from any massive galaxies. The color magnitude diagram of resolved stars in Virgo UFD1 shows narrow, metal poor red giant branch (RGB), which is very similar to the UFDs in the Local Group. by comparing RGB in this galaxy with 12 Gyr stellar isochrones, we estimate its distance, $d=16.4{\pm}0.4$ Mpc and mean metallicity, $[Fe/H]=-2.4{\pm}0.4$. We derive its integrated photometric properties and structural parameters : V-band absolute magnitude of $MV=-6.3{\pm}0.2$, effective radius of $84{\pm}7pc$, and central surface brightness of ${\mu}V,0=26.49{\pm}0.09$ mag arcsec-2. These properties are similar to these of Local Group UFDs. Virgo UFD1 is the first UFD discovered beyond the Local Group. These results indicate that it may be a fossil remnant of the first galaxies.

• Interaction and multiscale mechanics
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• 제4권1호
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• pp.17-34
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• 2011

This paper deals with the modeling of the plane frame structure-foundation-soil system. The superstructure along with the foundation beam is idealized as beam bending elements. The soil medium near the foundation beam with stress concentrated is idealized by isoparametric finite elements, and infinite elements are used to represent the far field of the soil media. This paper presents the modeling of shear wall structure-foundation and soil system using the optimal membrane triangular, super and conventional finite elements. Particularly, an alternative formulation is presented for the optimal triangular elements aimed at reducing the programming effort and computational cost. The proposed model is applied to a plane frame-combined footing-soil system. It is shown that the total settlement obtained from the non-linear interactive analysis is about 1.3 to 1.4 times that of the non-interactive analysis. Furthermore, the proposed model was found to be efficient in simulating the shear wall-foundation-soil system, being able to yield results that are similar to those obtained by the conventional finite element method.

• Structural Engineering and Mechanics
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• 제21권1호
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• pp.67-82
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• 2005

This study analyzes stress intensity factors for a number of periodic edge cracks in a semiinfinite medium subjected to a far field uniform applied load along with a distribution of eigenstrain. The eigenstrain is considered to be distributed arbitrarily over a region of finite depth extending from the free surface. The cracks are represented by a continuous distribution of edge dislocations. Using the complex potential functions of the edge dislocations, a simple as well as effective method is developed to calculate the stress intensity factor for the edge cracks. The method is employed to obtain the numerical results of the stress intensity factor for different distributions of eigenstrain. Moreover, the effect of crack spacing and the intensity of the normalized eigenstress on the stress intensity factor are investigated in details. The results of the present study reveal that the stress intensity factor of the periodic edge cracks is significantly influenced by the magnitude as well as distribution of the eigenstrain within the finite depth. The eigenstrains that induce compressive stresses at and near the free surface of the semi-infinite medium reduce the stress intensity factor that, in turn, contributes to the toughening of the material.

• Journal of Advanced Marine Engineering and Technology
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• 제39권10호
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• pp.1037-1043
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• 2015

In recent years, Floating Liquefied Natural Gas (FLNG) Unit have attracted considerable attention. Generally, liquefied natural gas (LNG) units are produced in onshore liquefaction terminals from gas supplied from onshore gas fields or large-scale offshore gas fields near the coast. However, the development of these gas fields has approached saturation. Large-scale offshore gas fields far from the coast, as well as undeveloped medium- and small-scale offshore gas fields, have recently attracted attention. Among several proposed concepts, the floating LNG plant in the form of the FLNG system was chosen for further evaluation and development, considering worldwide receiving infrastructure. The design of a 2.5 million tonne per annum FLNG unit has been completed with a capacity corresponding to that of modern onshore liquefaction plants. Various simulation tests were performed to evaluate the performance of the electrical power plant, focusing on the efficiency of the electrical system to secure the aspects of plant safety. This design study analyzes the electrical system for the FLNG unit to improve the safety of operation and maintenance in the field.

• 한국전자파학회논문지
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• 제12권7호
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• pp.1067-1075
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• 2001

본 논문에서는 시간영역 해석방법인 FDTD방법을 이용하여 환상 골진 혼 안테나의 corrugation의 개수와 위치를 바꿔가면서 전파반사 특성 및 방사패턴과 지향성를 분석하였다. 2차원 코딩을 함으로써 계산시간을 줄일 수 있었으며, 맥스웰 방정식을 원통좌표계로 이산화하여 코딩을 함으로써 좀더 정확한 결과를 얻을 수 있었다. corrugation이 있을 때가 없을 때보다 개구면에서 위상차가 조금 줄어들었으며 그 결과 S$_{11}$의 값과 지향성 값이 개선되었다. 그러나 corrugation 증가에 비례하여 성능이 개선되지는 아니하며 개구면에 위치한 corrugation이 안테나의 특성에 큰 영향을 줌을 알 수 있었다.

• 한국안광학회지
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• 제17권4호
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• pp.403-410
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• 2012

목적: 정시와 안경 및 콘택트렌즈 착용자의 조절반응량을 비교하고, 각 그룹내에서 굴절이상도와 조절래그의 상관성을 확인하고자 하였다. 방법: 안질환이 없고 굴절이상이 완전 교정된 72명(144안)을 대상으로 폐쇄형 자동굴절검사기로 측정한 굴절이상도를 사용하여 정시, 안경착용자 및 콘택트렌즈 착용자로 분류하였다. 이후 우세안, 나안시력 및 교정시력을 측정하고, 개방형 자동굴절검사기를 이용하여 단안 및 양안으로 원/근거리(5 m/33 cm)를 주시할 때의 굴절이상도를 측정하여 조절래그를 산출하였다. 결과: 좌우안 및 우세안/비우세안의 조절래그는 단안/양안주시 모두 통계적으로 유의한 차이가 없었으며, 단안주시의 조절래그가 양안주시보다 더 크게 검출되었다. 또한 남녀간의 조절래그는 단안주시는 남자가 컸지만 양안주시는 유의한 차이가 없었다. 근시도와 조절래그는 단안/양안주시 모두 근시안이 정시안에 비해 더 컸지만, 안경착용자와 콘택트렌즈 착용자의 조절래그는 단안/양안주시 모두 유의한 차이는 없었다. 전체 대상자의 굴절이상도와 조절래그 상관성은 단안/양안주시 모두 굴절이상도가 클수록 조절래그가 컸으며, 정시안과 콘택트렌즈 착용자는 단안/양안주시 모두 유의한 상관성이 있었으나 안경착용자는 단안/양안주시 모두 유의한 상관성이 없었다. 결론: 정시안과 근시안의 조절래그는 유의한 차이가 있고, 근시안 중 안경착용자와 콘택트렌즈 착용자의 조절래그는 유의한 차이가 없었다. 정시안과 콘택트렌즈 착용자의 굴절이상도는 조절반응량과 상관성을 보였다.

• 한국구조물진단유지관리공학회 논문집
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• 제4권4호
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• pp.109-119
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• 2000

PVDF film sensor was applied to measure the stress concentration for monitoring the structural integrity. The strain calibration of this film sensor was performed by the bending test of aluminum beam. The PVDF sensor and the electrical strain gage were bonded on the beam. When the beam was loaded, the output of electrical strain gage was compared with the output of the PVDF sensor. The waveform of PVDF sensor output was shown as the same form of the output of electrical strain gage. The gain was determined as 1.7 by comparing these two signals to determine the exact value of the strain. In order to experiment the stress concentration, the stress field was analyzed by finite element analysis. The tensile test of notched steel specimens was conducted to develop the measurement technique of stress concentration. The output voltage ratio between the PVDF sensor near the notch and the PVDF sensor far from the notch could give the information about the load bearing capacity of steel specimen.