• Explosives and Blasting
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• v.20 no.3
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• pp.25-38
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• 2002

터널 굴착선 여굴(Overbreak)은 발파공법에 의한 괄착 중에 필연적으로 발생하는 현상으로서 숏크리트, 라이닝 등의 보강비 추가 발생과 버력 처리량의 증대로 공기 및 공사비를 증가시키는 주요한 요인으로 작용한다. 또한 터널 굴착선 암반의 손상으로 균열층이 형성되거나 부석이 발생하여 안전문제를 야기시키기도 한다. 이러한 여굴 발생은 천공오차, 발파패턴의 오류, 잘못된 화약선정, 불규칙한 암반 특성 등에 그 원인이 있으나, 지금까지 터널 여굴은 천공 및 발파기술에 의해 좌우된다라는 인식이 대부분이었다. 그러나 여굴 발생에 중요한 원인으로 터널 굴착선 암반의 특성과 이에 적합한 발파패턴 및 화약류를 들 수 있다. 본 연구는 여굴 발생에 영향을 미치는 암반상태를 파악하기 위해서 터널 굴착선 주변암반의 균열정도, 강도, 불연속면의 간격, 방향, 간극, 충전물 상태 등의 6가지 요소를 이용하여 암반을 분류하는 발파암 분류법(BI)을 새로 제안하였고, 이 분류에 따라 외곽 공의 간격과 장약밀도를 달리 하는 발파패턴을 정립하였다. 또한 화약의 순폭도와 Air Deck 효과를 이용하여 장약밀도를 조절할 수 있는 N.D.C(New Deck Charge) 발파공법을 개발함으로써 여굴을 최소화할 수 있었다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.82-92
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• 2012

This study proposed a new non-destructive evaluation method for concrete bridge deck deterioration using ground penetrating radar (GPR). To calculate dielectric constant of the concrete bridge deck, an extended common mid-point (XCMP) method was developed for a two-layered structure using an air-coupled GPR antenna setup. The deterioration conditions of the concrete bridge deck such as deterioration depth was evaluated based on the dielectric constant and surface-to-average dielectric constant ratio of the concrete bridge deck. A GPR field test was conducted on an old concrete bridge with asphalt concrete surfacing to validate the new evaluation method. The test results showed that the newly proposed method estimated pavement thickness and deterioration depth of the concrete deck in a reasonable level.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.2
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• pp.54-59
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• 2010

The flight deck crew must manage complexity during daily flight operations. The Airline may obtain data regarding threats and errors through LOSA(Line Operations Safety Audits) on normal flights as predictive safety tool in Safety Management System of the Airline to actively improve the systems such as SOP(Standard Operation Procedure), training, evaluation and the TEM(Threat and Error Management) for the flight deck crew. The flight deck crew make errors when they fail managing threats. The crew mismanage around ten percent of threats and commit errors. The major mismanaged threats are aircraft malfunction, ATC(Air Traffic Communication), and wether threats. The effective countermeasures of TEM for manageing threats are leadership, workload management, monitor & cross check, Vigilance, communication environment and cooperation of the crew. It is important that organizations must monitor for the hazards of threats and improve system for the safer TEM environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.165-170
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• 2009

In this study, the flexural experiment was conducted to propose the one-way composite slab system composed of concrete and GFRP-Deckplate by comparing with the composite deck slab system with bar-mesh As a result of experiment, the specimens of the proposed GFRP-Deck composite slab were better than the specimens for comparison in the flexural performance. It is effective for the building structures exposed to air pollution or salt.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.1
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• pp.1-7
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• 2011

Basalt originates from volcanic magma and flood volcanoes, a very hot fluid or semifluid material under the earth's crust, solidified in the open air. Basalt is a common term used for a variety of volcanic rocks, which are gray, dark in colour, formed from the molten lava after solidification. Recently, attention has been devoted to continuous basalt fibers (CBF) whose primary advantage consists in their low cost, good resistance to acids and solvents, and good thermal stability. In order to investigate reinforcement effect, this paper did FEM analysis with shell element. The result were as follows; BCF deck plate did elastic behavior to 450 kN, reinforcement effect of basalt fiber (BF) was less. But BCF's perpendicular deflection occurred little about 23 mm comparing with RC deck plate in load 627 kN. Stiffness was very improved by basalt fiber reinforcement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.329-335
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• 2009

The purpose of this study is to provide the efficient method and guideline of controlling the cracking in bridge deck concrete due to differential drying shrinkage. Drying shrinkage cracking is mainly influenced by the moisture diffusion coefficient that determines moisture diffusion rate inside concrete structures. In addition to the diffusion coefficient, surface coefficient of concrete surface and relative humidity of ambient air simultaneously affect the moisture evaporation from concrete inside to external air outside. Within the framework of cracking shrinkage cracking mechanism, it is necessary to conceive the numerical analysis, which involves these three influencing factors to predict and control the shrinkage cracking of concrete. In this study, moisture diffusion and stress analysis corresponding to drying shrinkage on bridge deck are performed with consideration of diffusion coefficient, surface coefficient, and relative humidity of ambient air. From the numerical results, it is found that cracking behavior due to differential drying shrinkage of bridge deck concrete shows different feature according to three influencing factors and the methodology of controlling of drying shrinkage cracks can be suggested from this study.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.370-376
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• 2007

The purpose of this study is to measure the thermal conditions of the various cabins in a long cruise passenger ship which is an integration of the high level technological know-how. We did an experiment and found out the following problems. (1) The temperature from the damper is stable but the humidity varies lower. (2) Comparing A deck-located cabins to B deck-located cabins, A-deck located cabins' temperatures are higher because of the 24% more air supply. (3) More influences from outdoor climate makes the temperature of the outside cabin lower than the inside cabin. (4) In some cabins, there are vertical temperature differences of $4{\sim}6^{\circ}C$. (5) And $2{\sim}4^{\circ}C$ temperature differences are occurred at between 2-story bed. (6) Repeatability of measurement results are confirmed by 2 times measurements.

• Journal of Fisheries and Marine Sciences Education
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• v.12 no.1
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• pp.22-82
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• 2000

The ship hull construction materials of fishing boat has changed in order that wooden, steel, and fiber glass reinforced plastic(FRP). The fishing boat made from FRP has increased every year because that materials has proved excellent of the characteries for fishing boats construction members. Recently, FRP tend towards evasion for the pollution of air enviroment. Therefore. the materials of fishing boat construction must be exchanged by another one. Aluminium alloys must be recommended for fishing boats construction mateials because that is light weight and corrosion resisting in the sea water. Regulation of the standard of ship hull construction for aluminium alloys fishing boats did not enact laws in the interior now. Therefore, this regulation was studied by the following items. that is Rudder, Bottom construction, Side hull plate construction, Deck plate construction, piller. Water tight bulkhead, Deep tank, Fish tank, Stern construction, Superstructure, Deck house construction, Hatch, Engine room opening, Hatch opening, Bulwark, Welding and Rivet etc. A study on the regulation will be contributed to enact laws for fishing boat construction of aluminium alloys.

• Special Issue of the Society of Naval Architects of Korea
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• 2013.12a
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• pp.30-34
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• 2013

Prevention of exhaust gas back flow becomes a great interest to shipyards and shipowners in large container carriers because exhaust gas pollutes cargoes, flows back into the deck house and the engine room area through fresh air intakes and fan rooms, gives harmful damages to the crew's health and also gives thermal damages to electric equipments on the navigation deck. The phenomena of exhaust gas back flow has been studied with the analysis of sea trial records and wind tunnel tests and the height of the exhaust gas pipe, the front area of the deck house, the inflow speed and the position of the radar mast platform has been confirmed as the principal factors of exhaust gas back flow phenomena. The simple empirical formula to estimate exhaust gas back flow phenomena and the design guidances of exhaust gas related structures on deck has been introduced. In future, parametric studies for the exhaust gas back flow factors will be carried out with the CFD analysis. The results of this study will be the guide for development of the prevention method of exhaust gas back flow phenomena for large container carriers.

• Explosives and Blasting
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• v.28 no.2
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• pp.28-36
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• 2010

A study about economical blasting methods which can improve fragmentation and save explosive in blasting is in progress. One of the blasting methods is an air decking method making air layers in boreholes. However, it is difficult to apply this method to the boreholes filled with water. In this study, an underwater Air Tube was manufactured and tried to place it at a certain location in a water filled borehole. It was found that the application of underwater air tube in wet boreholes could improve the fragmentation and save 10~15% of the explosives.