• NEWSLETTER 전기공업
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• no.99-20 s.237
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• pp.10-21
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• 1999

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1167-1173
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• 2013

This study aimed to calculate the CFFs (critical flow functions) of a sonic nozzle bank with a 12-nozzle package within 1 s. Toward this end, the Helmholtz free energy of natural gas was formulated by using the AGA8-dc equation of state in a form without integral terms, and thereafter, thermodynamic properties such as the enthalpy, entropy, speed of sound, and heat capacity, which are used in CFF calculation, were derived in analytical form. As a result, the calculation time of CFFs was improved from 6.7 s in a previous study to 0.6 s per 12-nozzle package and kept almost constant regardless of the number of components in natural gas. Furthermore, it was confirmed that the calculated CFF values were in agreement with the results of a CFF international comparison test carried out under ISO management in 1998-1999.

• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.165-176
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• 2005

Natural gas in deep sediment may occur in three phases based on the physical and chemical conditions. If the concentration of gas in pore water is less than the solubility, gas is dissolved. If the concentration of gas is greater than its solubility (water is saturated or supersaturated with gas), gas occurs as a fee gas below the gas hydrate stability Lone (GHSZ) and is present as solid hydrate within the GHSZ. The knowledge of gas concentration in deep sediment appears critical to determine the phase of natural gases and to understand the formation and distribution of gas hydrate. However, reliable data on gas concentration are usually available only from the upper section of marine sediment by the headspace gas technique, which is widely used for sampling of gases from the sediments. The headspace gas technique represents only a fraction of gases present in situ because sediments release most of the gases during recovery and sampling. The PCS (Pressure Core Sampler) is a downhole tool developed to recover a nominal $1{\cal}m$ long, $4.32{\cal}cm$ diameter core containing $1,465cm^3$ of sediment, pore water and gas at in situ pressure up to 68.9 MPa. During Leg 204, the PCS was deployed at 6 Sites. In situ methane gas concentration and distribution of gas hydrate was measured by using PCS tool. Characteristics of methane concentration and distribution is different from site to site. Distribution of gas hydrate in the study area is closely related to characteristics of in situ gas concentration measured by PCS.

• Journal of the Korean Institute of Gas
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• v.7 no.1 s.18
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• pp.41-46
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• 2003

The Phase and temperature changes of large clusters formed in a free jet expansion of acetylene in 14atm and 233K has been studied. The cluster has been treated as a sphere composed of many shells. A mean diameter of 4.88 microns was obtained by modeling the experimental cooling curve of clusters based on evaporation and heat conduction theory.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.787-791
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• 1998

본 논문에서는 ${\alpha}$, ${\beta}$분리 및 결합형, 피드 포워드형, 미분선행형(PI형)의 2-자유도 PID제어기의 각 종류에 대해 파라메터 변화에 따른 특성을 가스 터빈의 연료 제어계통 전달함수를 이용해 비교 고찰하였다. ${\alpha}$, ${\beta}$는 제어기의 출력 특성에 크게 영향을 미치나 ${\gamma}$는 크게 영향을 미치지 않는 것으로 나타났고 각 제어기의 특성에서는 ${\alpha}$, ${\beta}$결합형이 가장 양호한 출력 특성이 나타났다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.5
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• pp.413-430
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• 2011

Consideration on the explosion resistant design of infrastructure has increased in the recent years. The explosion load is caused by gas explosion or bomb blast. In this study an analytical model is developed, whereby the tunnel structure is divided in several elements that are schematized as single degree of freedom mass-spring-dashpot systems on gas explosion. Using this simple model a sensitivity analysis has been carried out on tunnel structure design parameters such as explosive peak pressure, duration of the load, thickness of structure, burial depth. Finite element method was used to investigate the dynamic response and plastic zone of a tunnel under gas explosion. And it was found from the comparison of the analysis results that there are slight differences in the response of the intermediate wall between the single degree of freedom mass-spring-dashpot model and FEM.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.672-675
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• 2009

동해 울릉분지에서 취득된 다중채널 탄성파자료 해석에 의하면 이 지역에는 가스하이드레이트 부존가능성을 지시하는 해저모방반사면, 탄성파침니/칼럼, 음향공백대, 증폭반사면, 가스분출 구조 등을 포함하는 5가지 탄성파 지시자가 존재한다. 가장 대표적인 지시자인 해저모방반사면은 연구지역의 남쪽사면의 경우 연속성이 양호하고 강한 진폭을 갖는 반면, 북쪽 중앙분지에서는 상대적으로 진폭이 약하고 연속성이 불량하다. 반사도 감소 및 속도 풀업 특징을 갖는 탄성파 침니/칼럼구조는 중앙분지와 북동쪽해역에 주로 분포하며 가스하이드레이트 혹은 가스유체의 부존가능성을 시사해준다. 반사강도가 약화되어 나타나는 음향공백대는 저탁류/원양성 퇴적물이 분포하는 중앙분지에 부분적으로 발달하며, 칼럼과 연계된 음향공백대는 북동쪽 사면저부에 주로 분포한다. 해저모방반사면의 하부에 위치하는 증폭반사면은 연구지역의 서쪽 사면에 분포하며 강한 음의 진폭특성으로 보아 자유가스를 함유한 층으로 해석된다. 가스분출구조는 주로 쇄설성 퇴적물이 우세한 조사지역의 남쪽 대륙사면지역에 광범위하게 분포하며 돔구조 혹은 폭마크 등을 수반한다.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1567-1569
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• 2001

자유 도전성 파티클이 전계의 영향으로 GIS (Gas Insulated Switchgear) 외함전극 내부표면으로부터 가스공간을 가로질러 중앙도체까지 튀어 오르게 되면 절연파괴가 발생할 가능성이 매우 높아진다. 그러므로 파티클이 튀어 오르는 높이는 절연파괴 발생 위험도를 평가하는 데에 중요한 자료로 활용될 수 있다. 본 논문에서는 GIS 내부에 자유 도전성 파티클이 혼입된 상태에서 GIS가 운전중일 때 GIS 외부에서 파티클 상승높이를 추정하는 방안을 세계 최초로 제시함으로써 현재까지 해결되지 않은 도전성 파티클 결함에 대한 절연파괴 위험도 평가가 가능하게 되었다.

• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.106-110
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• 2021

The emergence of new hydrogen-related technologies and new businesses has expanded the need to reorganize systems in related fields such as manufacturing liquefied hydrogen (charging), and manufacturing liquefied hydrogen storage tanks and containers, and special applications continue to increase. Accordingly, we intend to establish and implement measures to strengthen safety management to share the status of designation of special hydrogen-related regulatory projects and secure minimum safety.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.187-195
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• 2015

The gas explosions in offshore installations are known to be very severe according to its geometry and environmental conditions such as leak locations and wind directions, and a dynamic response of structures due to blast loads depends on the load profile. Therefore, a parametric study has to be conducted to investigate the effects of the dynamic response of structural members subjected to various types of load shapes. To do so, a series of CFD analyses was performed using a full-scale FPSO topside model including detail parts of pipes and equipments, and the time history data of the blast loads at monitor points and panels were obtained by the analyses. In this paper, we focus on a structural dynamic response subjected to blast loads changing the magnitude of positive/negative phase pressure and time duration. From the results of linear/nonlinear transient analyses using single degree of freedom(SDOF) and multi-degree-of freedom(MDOF) systems, it was observed that dynamic responses of structures were significantly influenced by the magnitude of positive and negative phase pressures and negative time duration.