• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.1
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• pp.1-9
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• 2018

All ships should ensure stability in accordance with IMO regulations. However, GM is only used to determine ship stability because it takes a lot of time to validate all regulations. This is a problem given that the safety of vessels cannot be guaranteed, potentially leading to accidents. There is a need for a more intuitive and comprehensive method of confirming the stability of ships. This study developed a stability index that expresses ship stability in one value. An index equation is defined based on the 6 stability criteria for ships prescribed by IMO and the result of calculating the ship stability of a model ship. A stability index has been derived for each loading condition by applying the index equation to the same ship. It can clearly be seen that this stability index appropriately explains the criteria. In other words, it is possible to assess ship stability with one value and confirm whether the ship stability satisfies IMO regulations. This index will help masters and officers more easily and accurately check ship stability.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.107-107
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• 2019

하천은 과거부터 현재까지 인간의 삶에 있어서 중요한 공간이며 환경적, 생태적으로도 중요한 가치를 지니고 있다. 특히, 하천은 물과 흙으로 이루어져 있기 때문에 수생물이 살아갈 수 있는 독특한 생태 서식처 공간을 제공한다. 국내에서는 1980년대 말부터 하천환경의 개선 및 복원에 대해 관심과 인식을 높이고 공감대를 형성하여 훼손된 하천을 원래 모습으로 되돌리는 사업을 수행하였다. 이러한 하천복원사업이 하천에 서식하는 수생물의 어떠한 영향을 주는지 분석하기 위해 최근에는 다양한 물리서식처 분석이 수행되고 이를 통해 각종 복원계획을 수립하고 있다. 하천복원사업을 통한 생태유량 재산정, 보 철거의 영향, 다양한 복원기법을 통한 수생물에 미치는 영향 파악 등을 들 수 있다. 그러나 이러한 기존 연구들은 하천복원사업으로 인한 수리특성과 수생 서식처의 변화를 살펴보는 간접적인 영향에 대한 내용이었다. 그러나 직접적으로 영향을 미치는 하도의 단면을 재설계하고 다양한 복원기법을 적용하여 그 영향을 파악하는 연구도 수행되어야 할 것으로 판단된다. 본 연구는 수리학적으로 유리한 저수로 물길 조성 및 다양한 저수로 조성기법의 적용을 통해 우점종의 서식처에 미치는 영향에 대해 원주천을 대상으로 물리서식처 분석을 수행하였다. 대상구간은 원주천 중 상류에 위치한 900 m 구간으로, 대상 어종은 원주천의 중 상류에 서식하는 우점종인 참갈겨니를 목표로 하였다. 수리분석과 서식처분석은 각각 River2D 모형과 서식처 적합도 모형을 사용하였다. 서식처 적합도 모형에 사용된 서식처 적합도 곡선은 Gosse (1982)의 방법을 이용하여 구축하였으며, 수심, 유속, 기층을 모두 고려하여 물리 서식처 분석을 수행하였다. 저수로 물길 복원 조성을 위하여 수리학적으로 유리한 저수로 단면으로의 복원 및 거석, 여울/소 구조, 단면의 확폭을 통해 기존 자연형 하천과는 다른 복원을 조성하였다. 수리학적으로 유리한 저수로 물길 복원을 조성한 결과를 이용하여 물리서식처 분석을 수행하였을 때, 기존 자연하천인 현상태 대비 약 37% 가중가용면적이 악화되는 것으로 나타났다. 그러나 수리학적으로 유리한 저수로 단면의 설계 조건에서 거석, 여울/소 구조 및 단면의 확폭의 복원을 수행하였을 때 서식처가 최소 약 3%에서 최대 21%까지 가중가용면적이 향상되었다.

• Ecology and Resilient Infrastructure
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• v.6 no.1
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• pp.58-68
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• 2019

This present study conducted the impact of the restoration of low-flow channel on fish habitat in a reach of the Wonju Stream, Korea. The target species were Zacco koreanus, a dominant species in the middle- and upper-stream of Wonju Stream. The River2D model was used for the computation of the flow and the habitat suitability index model was used to estimate the quantity and quality of fish habitat using habitat suitability curves. In order to restore the study area, the low-flow channel was identified through the bankfull discharge of the study reach, and the best hydraulic section was designed. In addition, various restoration techniques were applied to the low-flow channel through rocks, pool/riffle structures, and the change of the channel width. Simulation results indicated that the restoration of the best hydraulic section effects decreased habitat suitability for the target species. However, when various restoration techniques were applied, the WUA (Weighted Usable Area) was improved by about 11%.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1684-1688
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• 2007

하천의 수위를 유지하거나 농업용수를 취수할 목적으로 하도 내에 조성되는 보는 현재 국내에 약 18,000개 정도가 있다. 그러나 최근 도시 인구집중화에 따른 농경지의 도시화, 토지이용의 변화, 취수 시설물의 통합, 시설의 노후화 등으로 많은 수의 보가 제 기능을 상실하고 있다. 이러한 보는 하천생태통로의 차단, 미생물 어류의 이동 단절, 수질의 악화 초래, 수변 생물서식처의 변화를 가져오고 있다. 기능이 상실된 보 가운데 곡릉천 곡릉2보를 철거함에 따른 상하류 하상변동을 해석하고자 미공병단의 HEC-6 모형을 이용하여 수치해석을 하였다. HEC-6 모형의 수치해석을 위해 곡릉천의 단면, 유사량, 입도분포, 수위-유량 곡선을 이용하였고, 보 철거 후 시간에 따른 유사이동량의 변화를 파악하고 보 상류의 하상세굴과 보 하류의 퇴적현상을 관찰하였다. 또한 보 철거 후 장기하상변동을 모의한 결과 곡릉천에서의 곡릉2보를 철거함으로 인한 평형하상으로 도달되는 시간은 20년 정도 소요되는 것으로 예측되었다. 이러한 기능이 상실된 보를 철거함으로 인해 하류에 미치는 물리적 영향의 분석은 하천 생태 복원을 위한 기초 자료로서 이용할 수 있을 것으로 판단된다.

• Bulletin of the Society of Naval Architects of Korea
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• v.2 no.1
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• pp.15-19
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• 1965

The stability curves are very important data to decide the seaworthiness of all kinds of ships among waves. Both statical and dynamical stability curves on a rectangular coordinate system have broadly been handled at ship yards or at the government concerned, up to data. As concerns a method of obtaining a statical stability curve on polar coordinate system, the papers were presented once. Also, it is of use to research the dynamical stability curve on polar coordinate system. Author treated of the dynamical stability curve by four different methods, and tried to set the stability indicator inboard, adopted those proposals, in order to give some aids for good navigation on the sea. Fig. 1. shows a drawing method in case of the position of centre of buoyancy can be previously pointed out on the line corresponding to its inclination. Fig. 2. shows a method used a statical stability curve on polar coordinate. Fig. 3. shows a method obtained by the most simplified means. Fig. 4. shows dynamical stability curve made by geometrical expression method, instead of dynamical lever. A simple stability indicator which was mechanized above characteristics is attempted by author as shown Fig. 5 and Fig.6. It is demanded at hand, for more advanced improvement of such indicator.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.216-219
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• 2011

신.재생에너지는 머지않아 고갈될 것이라 예측하고 있는 화석에너지의 대체에너지로서 대형 홍수와 국지적 집중호우, 가뭄과 전염병, 기근 등 우리인류의 생존을 위협하는 재앙을 어느 정도 줄일 수 있고, 온실효과 가스를 저감하고자 하는 하나의 방법으로서 가스배출량이 적은 수력, 풍력, 태양광 등의 재생에너지를 이용한 방법이다. 이 중 물은 무한적인 자원이 아니기 때문에 소중히 여기고 순환과정을 통하여 재활용 될 수 있고, 친환경적이고 장기적인 수명과 다른 자원을 사용하는 발전소들보다 더 효율적이며 복원 가능성이 크고 다른 오염유발 에너지 자원을 대신한다. 본 연구에서는 경상북도 북부지역 5개 지점의 소수력발전 후보지점에 대한 평 갈수기 및 홍수기의 유량측정에서 수위-유량관계곡선식의 유도등의 목적을 달성하기 위하여 2009년 3월부터 2010년 9월까지 5개 지점을 대상으로 현지조사 및 자료수집, 측량작업, 유량측정 등을 실시하였다. 본 유량측정을 통하여 경상북도 북부지역의 최적 소수력 발전지점 선정을 위한 기초자료를 제공할 수 있을 것으로 판단된다.

• Journal of the Korean Magnetics Society
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• v.14 no.3
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• pp.109-113
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• 2004

GMR isolator was modeled using a Wheatstone bridge which is profitable for transmitting rectangular wave digital data, and the output voltage characteristics in relation to the input current were investigated in time domain. GMR isolator modeling was divided into two parts, namely magnetic and electric parts. The flow chart of the modeling was drawn in which measured MR curve of the spin valves were incorporated to obtain the electrical voltage output. For magnetic modeling, 3-dimensional model of planar coil was analyzed by FEM method to obtain the magnetic field strength corresponding to the input current. For electric modeling, resistance, inductance and capacitance of the planar coil were calculated and magnetic field waveform was obtained corresponding to the coil current waveform in time domain. Finally, MR-H curves of spin valves and the magnetic field waveform at the spin valves were composited to obtain the output voltage waveform of the isolator. Even though the amplitude of the coil current waveform was increased by 100％, decreased by 90％, or delayed by 10％ of the period compared with the input current, similar transmitted output voltage waveform to the input current waveform was obtained due to hysteretic characteristics of the spin valves at the transmission speed of over 400 Mbit/s.

• Journal of Soil and Groundwater Environment
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• v.10 no.3
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• pp.38-45
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• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethylene (TCE)-contaminated aquifer. A series of single-well natural drift tests (SWNDTs) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Three field tests, Push-pull Transport Test, Drift Biostimulation Test, and Drift Surrogate Activity Test, were performed in sequence. Initial rate of toluene degradation was much faster than the rate of bromide dilution resulting from natural groundwater drift, indicating stimulation of indigenous toluene-oxidizing microorganisms. Transformation of ethylene, a surrogate probing overall activity of TCE transformation, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolueneoxidizing microorganisms stimulated may express a orthomonooxygenase enzyme. Also in situ transformation of TCE was confirmed by greater retardation of TCE than bromide after the stimulation of toluene-oxidizing microorganisms. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing orthomonooxygenase enzymes. The simple, low-cost field test method presented in this study provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism, which has previously hindered application of this technology to groundwater remediation.

• Conservation Science in Museum
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• v.12
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• pp.59-69
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• 2011

The conservation treatment and production technique of Yongmuntujoeunpanpi-Angyo(Saddle Ornament) at Hwangnamdaechong were: The conservation treatment removed foreign material by using both chemical method and physical method to reinforce and to recover area by jointing that was destroyed and weakened. Not only Angyogeumgu but also Jwamokseongeumgu was made of 99wt% or more silver (Ag), and Wondujeong, Naeyeongeumgu and Bokryung were produced by amalgam gold plaiting. Not only Angyogeumgu but also Jwamokseongeumgu that was cast with silver plate was jointed by folding both and putting Naeyeongeumgu on it and then nailing gild ofwondujeong at specific interval. A tree that grew up in curve was used, and it was adhered by plain weave fabric of hemp cloth and wool.

• Journal of the Korean Geographical Society
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• v.48 no.6
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• pp.837-855
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• 2013

The remains and relics such as wood vessel, shell middens and acorn hollows related to marine environments were excavated at Bibong-ri, Changnyeong-gun, Gyeongsangnam-do, South Korea, approximately 70km apart from the Nakdong River mouth. The sea-level changes were reconstructed based on characteristics of shell middens and acorn hollows, sedimentary facies, AMS dating, and diatom analysis. The shell middens and acorn hollows were constructed during the early Neolithic Age and provide information on the paleo-sea level, because of influences of marine processes. The sedimentary facies are classified into a bedrock, base gravel and Holocene sediment (marine, terrestrial and back marsh sediments), upward. The sea level fluctuated during the middle Holocene is in harmony with those in Sejuk-ri, Ulsan and Pyeongtaek. In particular, the sea level at Bibong-ri of study area was higher than the mean high tidal level in Gimhae by approximately 1m during 5,000yr BP and maintained the stable condition during 4,000yr BP.