• Bulletin of the Society of Naval Architects of Korea
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• v.54 no.4
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• pp.39-46
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• 2017

Jack-up drilling rigs are widely used in offshore oil and gas exploration industry. It is originally designed for use in the shallow waters less than 60m of water depth; there is growing demand for their use in deeper water depth over 150m and harsher environmental conditions. In this study, global in-place analysis of jack-up rig leg for North-sea oil well is performed through numerical analysis. Firstly, environmental conditions and seabed characteristics at the North-sea are collected and investigated measurements from survey report. Based on these data, design specifications are established and the overall basic design is performed. Dynamic characteristics of the jack-up rig for North-sea are considered in the global in-place analysis both leg and hull and the basic stability against overturning moment is also analyzed. The structural integrity of the jack-up rig leg/hull is verified through the code checks and the adequate safety margin is observed. The uncertainty in jack-up behaviour is greatly influenced by the uncertainties in the soil characteristics that determine the resistance of the foundation to the forces imposed by the jack-up structure. Among the risks above mentioned, the punch-through during pre-loading is the most frequently encountered foundation problem for jack-up rigs. The objective of this paper is to clarify the detailed structure and installation engineering matters for prove the structural safety of jack-up rigs during operation. With this intention the following items are addressed; - Characteristics of structural behavior considering soil effect against environmental loads - Modes of failure and related pre-loading procedure and parameters - Typical results of structural engineering and verification by actual measurement.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.24-34
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• 2008

To mitigate the climate change and global warming, various technologies have been internationally proposed for reducing greenhouse gas emissions. Especially, in recent, carbon dioxide capture and storage (CCS) technology is regarded as one of the most promising emission reduction options that $CO_2$ be captured from major point sources (eg., power plant) and transported for storage into the marine geological structure such as deep sea saline aquifer. The purpose of this paper is to review the latest progress on the development of technologies for $CO_2$ storage in marine geological structure and its perspective in republic of Korea. To develop the technologies for $CO_2$ storage in marine geological structure, we carried out relevant R&D project, which cover the initial survey of potentially suitable marine geological structure fur $CO_2$ storage site and monitoring of the stored $CO_2$ behavior, basic design for $CO_2$ transport and storage process including onshore/offshore plant and assessment of potential environmental risk related to $CO_2$ storage in geological structure in republic of Korea. By using the results of the present researches, we can contribute to understanding not only how commercial scale (about 1 $MtCO_2$) deployment of $CO_2$ storage in the marine geological structure of East Sea, Korea, is realized but also how more reliable and safe CCS is achieved. The present study also suggests that it is possible to reduce environmental cost (about 2 trillion Won per year) with developed technology for $CO_2$ storage in marine geological structure until 2050.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.237-248
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• 2017

Frequent terror or military attack by explosion, impact, fire accidents have occurred recently. These attacks and incidents raised public concerns and anxiety of potential terrorist attacks on important infrastructures. However, structural behavioral researches on prestressed concrete (PSC) infrastructures such as Prestressed Concrete Containment Vessel (PCCV) and Liquefied Natural Gas (LNG) storage tanks under extreme loading are significantly lacking at this time. Also, researches on possible secondary fire scenarios after terror and bomb explosion has not been performed yet. Therefore, a study on PSC structural behavior from an blast-induced fire scenario was undertaken. To evaluate the blast-fire combined resistance capacity and its protective performance of bi-directional unbonded PSC member, blast-fire tests were carried out on $1,400mm{\times}1,000mm{\times}300mm$ PSC specimens. Blast loading tests were performed by the detonation of 25 kg ANFO explosive charge at 1.0 m standoff distance. Also, fire and blast-fire combined loading were tested using RABT fire loading curve. The test results are discussed in detail in the paper. The results can be used as basic research references for related research areas, which include protective design simulation under blast-fire combined loading.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.761-766
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• 2020

Phenylamine derivatives are substances that have a biochemical action and are widely applied as psychotropic drugs. In particular, with regard to the quantitative analysis of substances such as ephedrine, amphetamine, pentermine, and dopamine, many previous studies such as electrochemical, vacuum ultraviolet method, and gas chromatography have been conducted. However, there have not been many studies on the structural characteristics of molecular units. Therefore, In this study, we used (HyperChem8.0's, HC) semi-empirical PM3 method to calculate the total energy, band gap, electrostatic potential, and net charge of ephedrine, amphetamine, pentamine and dopamine to investigate the chemical properties of each derivative according to the molecular structure change. The results showed that for total energy -43,171.8, -32,9538.3, -36,407.3 and -43,061.2 Kcal/mol, respectively, while for band gaps, 10.16379377, 9.9531666, 9.7878002 and 9.0589282 eV. Also, for electrostatic potentials, 1.301~-0.045, 1.694~0.299, 0.694~-0.158 and 1.587~-0.048 respectively. Finally, looking at the distribution of net charges, the oxygen atoms, nitrogen atoms and carbon atoms were -0.312~-0.242, -0.161~-0.051 and +0.13~-0.12 respectively. These results are expected to lead to chemical action centered on phenyl radicals and oxygen and nitrogen atoms common to phenethylamine derivatives.

• Membrane Journal
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• v.25 no.5
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• pp.373-384
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• 2015

In the past few decades, polymeric membrane has played an important role in gas separation applications. For the separation of $CO_2$, one of greenhouse gases, high permselectivity, long-term stability and scale-up are needed. However, conventional polymeric membranes have shown a trade-off relation between permeability and selectivity while inorganic materials are highly permeable but expensive. Mixed matrix membranes (MMMs) combining the advantages of both polymeric and inorganic materials have become a possible breakthrough for the next-generation gas separation membranes. The MMMs could be either symmetric or asymmetric but the latter is more preferred to improve the permeance. Important factors influencing the MMM fabrication include homogeneous distribution of inorganic particles and good interfacial contact between inorganic filler and organic matrix. Recently, metal organic frameworks (MOFs) have received much attention as a new class of porous crystalline materials and a potential candidate for $CO_2$ separation. Zeolitic imidazolate frameworks (ZIFs), a sub-branch of MOFs, are the most widely used in MMMs due to small particle size and appropriate pore size for $CO_2$ separation. One of the major issues associated with the incorporation of porous particles in a polymeric membrane is to control the microstructure of the porous particle materials such as particle size, orientation, and boundary conditions etc. In this review, major challenges surrounding MMMs and the strategies to tackle these challenges are given in detail.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.151-151
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• 1999

금속-산화막-반도체(MOS) 소자를 이용하는 집적회로의 발전은 게이트 금속의 규격 감소를 필요로 한다. 규격감소에 따른 저항 증가가 중요한 문제점으로 대두되었으며, 그동안 여러 연구자들에 의하여 금속 게이트에 관련된 연구가 진행되어 왔다. 특히 저항이 낮으며 녹는점이 매우 높은 내화성금속(refractory metal)인 텅스텐(tungsten, W)이 차세대 MOS 소자의 유력한 대체 게이트 금속으로 제안되었다. 텅스텐은 스퍼터링(sputtering)과 화학기상 증착(CVD) 방식을 이용하여 성장시킬 수 있다. 스퍼터링에 의한 텅스텐 증착은 산화막과의 접착성은 우수한 반면에 증착과정 동안에 게이트 산화막(SiO2)에 손상을 주어 게이트 산화막의 특성을 열화시킬 수 있다. 반면, 화학기상 증차에 의한 텅스텐 성장은 스퍼터링보다 증착막의 저항이 상대적으로 낮으나 산화막과의 접착성이 좋지 않은 문제를 해결하여야 한다. 본 연구에서는 감압 화학기상 증착(LPCVD)방식을 이용하여 텅스텐 게이트 금속을 100~150$\AA$ 두께의 게이트 산화막(SiO2 또는 N2O 질화막)위에 증착하여 물리 및 전기적 특성을 분석하였다. 물리적 분석을 위하여 XRD, SEM 및 저항등이 증착 조건에 따라서 측정되었으며, 텅스텐 게이트로 구성된 MOS 캐패시터를 제작하여 절연 파괴 강도, 전하 포획 메커니즘 등과 같은 전기적 특성 분석을 실시하였다. 특히 텅스텐의 접착성을 증착조건의 변화에 따라서 분석하였다. 텅스텐 박막의 SiO2와의 접착성은 스카치 테이프 테스트를 실시하여 조사되었고, 증착시의 기판의 온도에 민감하게 반응하는 것을 알 수 있었다. 또한, 40$0^{\circ}C$ 이상에서 안정한 것을 볼 수 있었다. 텅스텐 박막은 $\alpha$ 및 $\beta$-W 구조를 가질 수 있으나 본 연구에서 성장된 텅스텐은 $\alpha$-W 구조를 가지는 것을 XRD 측정으로 확인하였다. 성장된 텅스텐 박막의 저항은 구조에 따라서 변화되는 것으로 알려져 있다. 증착조건에 따른 저항의 변화는 SiH4 대 WF6의 가스비, 증착온도에 따라서 변화하였다. 특히 온도가 40$0^{\circ}C$ 이상, SiH4/WF6의 비가 0.2일 경우 텅스텐을 증착시킨 후에 열처리를 거치지 않은 경우에도 기존에 발표된 저항률인 10$\mu$$\Omega$.cm 대의 값을 얻을 수 있었다. 본 연구를 통하여 산화막과의 접착성 문제를 해결하고 낮은 저항을 얻을 수 있었으나, 텅스텐 박막의 성장과정에 의한 게이트 산화막의 열화는 심각학 문제를 야기하였다. 즉, LPCVD 과정에서 발생한 불소 또는 불소 화합물이 게이트의 산화막에 결함을 발생시킴을 확인하였다. 향후, 불소에 의한 게이트 산화막의 열화를 최소화시킬 수 있는 공정 조건의 최저고하 또는 대체게이트 산화막이 적용될 경우, 개발된 연구 결과를 산업체로 이전할 수 있는 가능성이 높을 것을 기대된다.

• Journal of the Korean Institute of Gas
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• v.14 no.5
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• pp.13-18
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• 2010

This paper presents the development of an integrated control and safety management system for 9% nickel steel LNG storage tank. The new system added the measuring equipment of pressure, displacement and force compared to the conventional measurement and control system. The measured data has simultaneously been processed by integrating and analyzing with new control equipments and safety management systems. The integrated control and safety management system, which may increase a safety and efficiency of a super-large full containment LNG storage tank, added additional pressure gauges and new displacement/force sensors at the outer side wall and a welding zone of a stiffener and top girder of an inner tank, and the inner side wall of a corner protection tank. The displacement and force sensors may provide failure clues of 9% nickel steel structures such as an inner tank and a corner protection, and a LNG leakage from the inner tank. The conventional leak sensor may not provide proper information on 9% nickel steel tank fracture even though LNG is leaked until the leak detector, which is placed at the insulation area between an inner tank and a corner protection tank, sends a warning signal. Thus, the new integrated control and safety management system is to collect and analyze the temperature, pressure, displacement, force, and LNG density, which are related to the tank system safety and leakage control from the inner tank. The digital data are also measured from control systems such as displacement and force of 9% nickel steel tank safety, LNG level and density, cool-down process, leakage, and pressure controls.

• 한국가스학회:학술대회논문집
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• 2003.10a
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• pp.120-125
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• 2003

본 연구는 원자력 발전소에 있는 방화벽의 케이블 관통부위에 설치된 CPFS(Cable Penetration Fire Stop)시스템 안에서 일어나는 동적열전달 현상을 3 차원으로 나타낼 수 있는 시험시뮬레이터에 사용될 수학적 모델과 수치계산 알고리즘의 개발에 관한 것이다. CPFS 내에서 일어나는 열전도 현상을 나타내는 지배방정식은 주어진 조건들 하에서 포물선형 편미분방정식(Parabolic PDE)으로 나타난다. 문제를 단순화하기 위해 열의 흐름을 두 성분으로 나누었다 즉, 케이블과 평행한 선을 따라서 일어나는 열전도와 벽면과 평행한 평면 위에서 일어나는 열전도로 나누었다. 먼저 선을 따라 일어나는 동적 열전도 현상을 나타내는 PDE를 연속과완화(SOR: Successive Over-Relaxation)를 적용하여 유한한 불연속점들에 대한 연립 상미분방정식(ODE)으로 전환했고, 그 연립방정식은 ODE Solver 를 이용하여 풀 수 있었다. 둘째로, 각 불연속 점에 위치한 평면 위에서 일어나는 열전도를 계산하기 위해서, 유한요소의 합을 근사식으로 이용하여 PDE를 ODE로 전환해서 계산하는 유한요소법(Finite Element Method)이 이용된다. 여기서 시간과 공간의 함수 T(x, y, z, t)인 온도는 각 선의 점들과 각 평면의 요소들에 대해서 일정한 시간간격으로 초기온도와 경계온도를 업데이트하여 계산을 반복한다. 이러한 일련의 계산결과를 바탕으로 CPFS 시스템 내에서의 온도분포의 동적인 변화를 해석한다. 결론적으로 관통하는 케이블이 CPFS 시스템의 온도분포에 매우 중요한 역할을 한다는 것을 알 수 있다. 시뮬레이션 결과는 CPFS 내의 온도분포를 쉽게 이해할 수 있도록 3 차원 그래픽으로 나타냈으며, 상용소프트웨어 FEMLAB 으로 계산한 결과와 비교해서 개발된 모델과 계산 알고리즘의 정당성을 보였다. 맞이하고 있음을 볼 수 있다. 국내광업이 21C 급변하는 산업환경에 적응하여 생존하기 위해서는 각종 첨단산업에서 요구하는 소량 다품종의 원료광물을 적기에 공급 할 수 있는 전문화된 기술력을 하루속히 확보해야 하며, 이를 위해 고품위의 원료광물 확보를 위한 탐사 및 개발을 적극 추진하고 가공기술의 선진화를 위해 선진국과의 기술제휴 등 자원산업 글로벌화 정책이 절실히 요구되고 있음을 알 수 있다. 또한 삶의 질을 향상시키려는 현대인의 가치관에 부합하기 위해서는 각종 소비제품의 원료를 제공하는 광업의 본래 목적 이외에도 자연환경 훼손을 최소화하며 개발 할 수밖에 없는 구조적인 어려움에 직면할 수밖에 없다. 이처럼 국내광업이 안고 있는 여러 가지 난제들을 극복하기 위해서는 업계와 정부가 합심하여 국내광업 육성의 중요성을 재인식하고 새로운 마음가짐으로 관련 정책을 수립 일관성 있게 추진해 나가야 할 것으로 보인다.의 연구 결과를 요약하면 다음과 같다. 첫째, 브랜드 이미지와 서비스 품질과의 관계에서 브랜드이미지는 서비스 품질의 선행변수가 될 수 있음을 증명하였으며 4개 요인의 이미지 중 사풍이미지를 제외한 영업 이미지, 제품 이미지, 마케팅 이미지가 서비스 품질에 영향을 미치고 있음을 알 수 있다. 둘째, 지각된 서비스 품질과 가격 수용성과의 관계에서, 서비스 품질은 최소 가격에 신뢰서비스 요인에서 정의 영향을 미치고 있으나 부가서비스, 환경서비스에서는 역의 영향을 미침을 알수 있고, 최대 가격에 있어서는 욕구서비스 요인은 정의 영향을 미치지만 부가서비스의 경우에는 역의 영향을 미치고 있음을 알 수 있다. 셋째, 서비스품질과 재 방문 의도와의 관계에 있어서 서비스품질은 재 방문 의도에 영향을 미침을 알 수 있다. 따라서 브랜드 이미지는 서비스품질의 선행변수가 될 수 있으며, 서비스품질은 가격 수용성과 재방문 의도에 영향을 미치고 있음을 알 수

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.29-36
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• 2007

Recent seismic surveys have shown that the presence of methane hydrate (MH) in sediments has significant influence on seismic attenuation. I have used vertical seismic profile (VSP) data from a Nankai Trough exploratory well, offshore Tokai in central Japan, to estimate compressional attenuation in MH-bearing sediments at seismic frequencies of 30-110 Hz. The use of two different measurement methods (spectral ratio and centroid frequency shift methods) provides an opportunity to validate the attenuation measurements. The sensitivity of attenuation analyses to different depth intervals, borehole irregularities, and different frequency ranges was also examined to validate the stability of attenuation estimation. I found no significant compressional attenuation in MH-bearing sediments at seismic frequencies. Macroscopically, the peaks of highest attenuation in the seismic frequency range correspond to low-saturation gas zones. In contrast, high compressional attenuation zones in the sonic frequency range (10-20 kHz) are associated with the presence of methane hydrates at the same well locations. Thus, this study demonstrated the frequency-dependence of attenuation in MH-bearing sediments; MH-bearing sediments cause attenuation in the sonic frequency range rather than the seismic frequency range As a possible reason why seismic frequencies in the 30-110 Hz range were not affected in MH-bearing sediments, I point out the effect of thin layering of MH-bearing zones.

• 한국지구물리탐사학회:학술대회논문집
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• 2002.09a
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• pp.46-66
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• 2002

High-resolution multichannel seismic data were collected in the coastal area near the Gori nuclear power plant to investigate Quaternary fault pattern and timing. A 12 channel streamer, a sparker, and a portable recorder were used for data acquisition. Because the group interval of the streamer was 6.25 m and the sparker can generate acoustic waves with the frequency content of up to 500 Hz, the data show a significant improvement both in horizontal and vertical resolution. The area surveyed is covered with 30-40 m thick Holocene sediments that constitute the mud belt along the southeastern coast of Korea. The survey area is characterized by the well discriminated Pleistocene and Holocene boundary and shallow gas-charged zones. A number of Quaternary faults were found in the sediment column, that are nearly vertical and extend north-south. The Quaternary faults, arranged at a spacing of a few hundred meters, suggest that they were formed in response to compression, although some of them reveal extensional characteristics. Locally, faults disrupt Incised-channel fills that are interpreted to have formed in the early stage of transgression after the beginning of the Holocene. Seismic sections suggest that shallow gas in the mud belt sediments made its way upward through the fractured fault planes. The tectonism responsible for the opening of the East Sea has not persisted since the late Miocene, but vigorous Quaternary faulting activity in the vicinity of the southeastern Korean Peninsula indicates that tectonic stability has yet to be achieved in this region underlain by the hotter than normal mantle.