• 대한기계학회논문집A
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• 제30권7호
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• pp.849-856
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• 2006

In this paper, fabric composite draping on hemisphere moulds were studied to find out the deformation behaviour of micro-tow structures of fabrics during draping and thermoforming. Aluminium and PVC foams were used to fabricate the hemisphere moulds for draping tests. In order to observe the local tow deformation pattern during the draping several specimens for microscopic observation were sectioned from the draped hemisphere structures. The effect of forming condition and mould properties on tow deformation was investigated by the microscopic observation of the tow parameters such as crimp angle. Normalization scheme was performed to compare tow parameter variations with different forming conditions. Stress-strain .elations of two different PVC foams (HT70 and HT110) were tested to investigate the effect of foam property on the micro-tow deformation during forming.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.222-235
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• 2017

In this study, finite element modeling was used to predict the material properties of tri-axially braided textile composite. The model was made based on an experimental test specimen which was also used to compare the final results. The full interlacing of tows was geometrically modelled, from which repeating parts that make up the whole braid called unit cells were identified based on the geometric and mechanical property periodicity. In order to simulate the repeating nature of the unit cell, periodic boundary conditions were applied. For validation of the method, a reference model was analyzed for which a very good agreement was obtained. Material property calculation was done by simulating uniaxial and pure shear tests on the unit cell. The comparison of these results with that of experimental test results showed an excellent agreement. Finally, parametric study on the effect of number of plies, stacking type (symmetric/anti-symmetric) and stacking phase shift was conducted.

• 한국병원경영학회지
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• 제1권1호
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• pp.203-247
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• 1996

This article reviews the art and practice of strategic management process in hospitals today, in order to help hospital administrators for managing strategic management system in their hospitals. The strategic management process model in this article is based on an integrated approach combining traditional environmental model with resource-based model of strategy. The components of the model are consisted of five steps: (1)formulating objectives, strategic assessment by external environmental analysis, internal capability analysis, TOWS analysis and marketing audit, (3)strategy choice considering context and criteria of choice, (4)program implementation through operational planning, resource allocation, and conversion, and (5)control by monitoring and evaluating hospital outputs. This article deals with many aspects of issues inherent in every step on this strategic management process.

• 한국항해항만학회지
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• 제39권2호
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• pp.83-88
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• 2015

Korea has a systemic problem with lack of engine maintenance, especially among the Commercial Fishing Vessel fleet. This results in a inordinate percent of SAR call-outs for vessels with engine failure. These SAR call-outs lead to a free tow to shore by KCG or by one of its volunteer associates. Although these tows are not a terrible economic burden on KCG, it is a burden in terms of time and resources mis-allocated. This paper proposes a Commercial Fishing Vessel Examination (CFVE) program modeled after the program run by USCG. It is expected that adopting the CFVE program, KCG may be able to create a culture of safety among fishermen; thus, replicating the USCG's success rates.

• 한국수산과학회지
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• 제28권6호
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• pp.708-719
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• 1995

This study is to estimate abundance of the Chesapeake Bay blue crab stock. Using 823 dredge tows which were conducted during the 1991 winter survey, blue crab abundance was estimated on the basis of newly developed methods which account for unequal dredge tow distances, size- and sex-specific heterogeneous overwintering spatial distributions, wintertime exploitation, the time period of quasi-hibernation, and dredge capture efficiency. The estimate of total abundance before correction by gear efficiency was 131.8 million crabs $(95\%\;C.I.\;=\;118.2\;million\;crabs\;to\;145.4\;million\;crabs),$ Dredge capture efficiency was estimated to be 0.474. Thus, the estimate of total abundance was calculated as 278.1 million crabs after correction by the efficiency factor.

• 한국세라믹학회지
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• 제50권6호
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• pp.528-532
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• 2013

Well-dispersed slurries of submicron-sized alumina powders were pressure-infiltrated in 3D preforms of mullite fibers and the effects of the particle size and infiltration pressure on the particle packing characteristics were investigated. Infiltration without pressure showed that the packing density increased as the particle size decreased due to the reduction of the friction between the particles and the fibers. The infiltrated preforms contained large pores in the large voids between the fiber tows and small pores in the narrow voids between the individual fibers. Pressure infiltration resulted in a packing density of 77% regardless of the particle size or the infiltration pressure(210 ~ 620 kPa). Pressure infiltration shortened the infiltration time and eliminated the large pores in preforms infiltrated with the slurries of smaller particles. The slurry pressure-infiltration process is thus an efficient method for the packing of matrix materials in various preforms.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.87-90
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• 2004

In this paper, geometrically non-linear finite element analyses were performed to study the mechanical behavior of the material system of the envelope of stratospheric airships. The microstructure of the load­bearing plain weave layer was identified and modeled. The Updated Lagrangian formulation was employed to consider the geometric non-linearity as well as the induced structural non-linearity for the fiber tows. The stress-strain behavior was predicted and the effective elastic modulus was calculated by numerical experiments. It was found the non-linear stress-strain curves were largely different from those by linear analysis with much higher non-linear elastic moduli. The difference was more distinguishable when the tow waviness was smaller.

• Design & Manufacturing
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• 제16권2호
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• pp.60-65
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• 2022

In the pultrusion process for the CFRP (Carbon fiber reinforced plastic) rectangular pipe, the drawing device is eseential which can continuously produces products and draws the carbon fiber tow. In addition, since the degree of cure changes depending on the temperature and the temperature ditribution of the curing mold changes depending on the pultrusion speed, the temperature distribution of the curing mold under certain conditions must be studied before processing. In this study, in the pultrusion process using a closed impregnation method, which has several advantages compared to the general pultrusion process using a open bath impregnation method, the drawing force required to pull the carbon fiber tows and the temperature distribution of the curing mold was analyzed to design the drawing device and the curing mold efficiently.

• 해양환경안전학회지
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• 제28권1호
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• pp.83-90
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• 2022

부선을 예인하는 예인선은 90.5 %가 총톤수 200톤 미만으로 대부분 선장 혼자 승무하고, 선원법상 근로시간 및 승무정원에 관한 규정을 적용받지 않는다. 따라서 부선을 예인하는 예인선의 선장은 항해당직 중 적절한 휴식을 취하지 못해 피로하게 되고, 부선을 예인하는 예인선은 불가피하게 무자격자인 갑판장과 교대로 항해당직을 수행하며 인적 감항능력을 충족하지 못한다. 또한 예인선의 선장 또는 소유자는 예인선이 부선을 예인할 때 선박직원법상 추가적으로 요구되는 최저승무기준을 준수하지 못하는 사례가 자주 발생하고 있다. 본 연구에서는 먼저 다음 사항에 대해 살펴보았다. (1) 선원법상 근로시간 및 승무정원에 관한 규정, (2) 선박직원법상 예인선의 갑판부 선박직원의 최저승무기준에 관한 규정, (3) 부선을 예인하는 예인선의 해양사고 사례. 그리고 예인선의 실효적인 해양사고 예방을 위해 예인선이 부선을 예인하는 경우에는 항해사 1명이 추가적으로 승무하도록 갑판부 선박직원의 최저승무기준을 개정할 것을 제안하였다. 특히 중대재해 처벌 등에 관한 법률은 2022. 1. 27. 시행되었다. 해양에서 인명사고가 동일한 원인으로 계속 발생하고, 그 원인이 제도적 미비로 인한 항해사의 피로라고 판단된다면 해양항만관청은 처벌을 받게 될 수 있으므로 이에 대해 대비할 필요가 있다고 본다.

• Composites Research
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• 제18권2호
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• pp.30-37
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• 2005

본 논문에서는 평직구조를 갖는 성층권 비행선 기낭의 하중막재에 대한 비선형 유한요소 해석 결과를 기술하였다. 평직구조를 갖는 하중막재의 미세구조를 3차원적으로 구현하였고, Updated Lagrangian 방법을 사용하여 기하학적 비선형성을 고려하였다 계산결과, 큰 변형률에서 비선형해석으로부터 얻은 응력-변형률 곡선은 선형해석의 결과와 큰 차이를 보였다. 또한 응력-변형률 곡선으로부터 얻은 비선형 탄성계수 값은 선형 탄성계수보다 큰 값을 보였는데 그 차이는 섬유의 굴곡도가 작은 경우 더욱 두드러지게 나타났다