• KSBB Journal
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• v.16 no.3
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• pp.233-236
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• 2001

Because of casehardenign effect of amorphous paclitaxel, residual solvents, methylene chloride and emthanol could not be reduced to the maximum value allowed, 600 ppm and 3,000 ppm, in accord with the guidelines issued by the International Conference on Harmonization (ICH, 1997), using rotary evaporation and successive drying in a vacuum oven. However, methylene chloride and methanol were reduced to 486 ppm and 403 ppm, respectively using supercritical $CO_2$ on purified paclitaxel. The optimum pressure and operating time were 80 bar and 30 min at fixed operating temperature ($40^{circ}C$). This approach serves as a novel application of supercritical fluid extraction to remove residual solvents from active pharmaceutical ingredients.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.471-478
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• 2018

Static tests of the composite wing structure were performed to verify damage tolerance design. Both 5 cases of DLLT and 3 cases of DULT were completed to meet requirements for static strength. After inducing BVID and open hole damages on the critical areas of the composite wing based on associated regulations, the DULT and fracture test were performed. In major wing parts, the measured strains and displacements agreed well with those of structural analysis. The initial structural fracture occurred at the area having minimum margin of safety as expected by analysis. As a result, it was confirmed that results from analytic model and strength evaluation were similar to behaviors of the composite wing structure.

• Fire Science and Engineering
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• v.16 no.1
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• pp.77-83
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• 2002

The objective of this study is to propose a method to prevent the possible stress corrosion cracking of a horizontal side-wall sprinkler head deflector in the same atmosphere of ammonia gas as it regulated in the UL (Underwriters Laboratory). A corrosion test is carried out for three types of specimen according to post-forming treatment, one of which is annealing, another sand blasting and the other no treatment. The observation of the test specimens with a metal micro-scope says that the tensile residual stress is a major factor causing corrosion cracking, and that a proper heat treatment can remove or reduce the residial stress and prevent a crack from occurring even in a severe corrosive atmosphers.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.347-350
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• 2004

전자상거래와 고객관계관리에서 고객의 개인화를 위해 사용되는 협동적 필터링 방안은 고객이 상품에 대해 표시한 선호도에 기반을 두어 선호도가 유사한 사용자를 찾고, 유사한 사용자의 선호도를 활용하여 추천할 상품을 선정하는 방안이다. 고객간의 유사도 계산과 상품에 대한 선호도 계산을 위한 다양한 방안들의 계산식에 대해서는 명확하게 정의되어 있으나, 이에 활용되는 데이터의 선정에 대해서는 명확한 규정이나 가이드라인이 존재하지 않는다. 즉, 몇 번 이상의 선호도를 표시한 사용자를 대상으로 추천을 수행할 것인지, 혹은 몇 번 이상 선호도가 표시된 상품을 추천에 활용할 것인지와 같은 데이터 선정에 활용되는 계수와 협동적 필터링의 추천 성과간의 관계에 대한 연구는 아직 부족하다. 본 연구에서는 협동적 필터링의 연구에 많이 활용되는 EachMovie 데이터를 가지고 협동적 필터링의 계수와 추천 성과간의 관계에 대해 실험적으로 연구하였다. 첫 번째는 몇 번 이상 선호도를 표시한 사용자를 협동적 필터링에 활용하는 것이 추천 성과를 높일 수 있는지에 대해 연구하였으며, 두 번째는 몇 번 이상 선호도가 표시된 상품을 고객에게 추천하는 것이 협동적 필터링의 추천 성과를 높일 수 있는가에 대한 연구를 수행하였다. 계수와 추천 성과간의 관계에 대한 두 가지 실험에서 선호도 표시의 한계가치(marginal value)가 점진적으로 감소하는 것을 볼 수 있었다. 본 연구의 결과는 협동적 필터링의 수행을 위한 효과적인 데이터의 선정에 도움을 줄 수 있을 것이다.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.29-36
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• 2005

We carried out discharge and fire extinguishing tests of new inert gas clean agent, which consists of $92\%$ nitrogen and $8\%$ carbon dioxide, as an alternative of Halon that is banned by Montreal Protocol to protect the ozone layer of the earth. Discharge and fire extinguishing tests were performed in $27m^3$ and $190m^3$ rooms with piping which allows gaseous agent to transport from storage to test rooms. We confirmed that it took less than regulation time, 60 seconds for the discharge of over $95\%$ initial charged amounts. Discharge test variables were piping length and orifice size. Fire extinguishing tests verified that this new inert gas clean agent is suitable for both n-Heptane fire and deep seated fire of wood crib.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1354-1360
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• 2013

In transmission system, reclosing scheme is very useful method to improve continuity of power supply and reliability of system. Especially, high speed reclosing which is used generally in transmission systems has a benefit improving transient stability. However, the reclosing can jeopardize the stability under the condition having high difference of voltage phase angle between both ends. Thus, this paper proposes optimal sequential reclosing scheme to improve transient stability due to reclosing operation. The optimal sequential reclosing is that each phase is closed sequentially considering transient energy. In this paper, 345kV and 154kV transmission system is modeled using EMTP (ElectroMagnetic Transient Program) to verify the performance and effectiveness of optimal sequential reclosing on transient stability. Also, Integral Square Error(ISE) method is used to assess the transient stability.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.01a
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• pp.115-118
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• 2015

최근 평균수명이 증가와 더불어 삶의 질이 중요시하고 건강한 삶을 누리고자하는 인류의 염원은 보건의료라는 보편적 가치에 동반 상승할 수 있는 산업과의 결합이 의료관광이라는 새로운 관광시장을 형성하였다. 의료관광은 시장규모가 1억 달러 이상에 이를 것으로 예상되는 고부가가치 산업이다. 또한 외국인을 상대 의료관광은 체류기간이 길고 지출비용도 일반 관광객의 3배 이상으로 지역경제 활성화에 큰 공헌을 하는 대표적인 신 성장 동력산업으로 보고 있다. 더불어 의료관광 추세가 의료서비스를 받으면서 휴양 레저 문화활동을 함께 즐기는 방향으로 발전될 것으로 예측하고 최근 단순 치료 목적이 아닌 방향으로 선회하고 있다. 그러나 국가 정책적 산업으로서 육성에 박차를 가하고는 있으나 의료 기반시설이 열악하고 관련 규정 및 제도적 미비점이 지금의 의료관광 산업에 발맞추지 못하는 실정이다. 이는 주변 경쟁국에 비해 인식부족과 세계시장에 대한 마케팅 활동 부족 및 의료관광 상품의 다양성 부족 등과 함께 의료관광이 활성화하기 위하여 여러 가지 제약이 되는 정책적 문제점들이 있다. 따라서 본 논문에서는 현행 우리나라의 의료관광에 대한 정책적 과제를 살펴보고 이를 개선하기 위한 제도적 개선방안을 모색하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.715-724
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• 2010

K-water has used satellite networks for 12 years for hydrological observation in various parts such as remote data acquisition and providing information including flood forecasting. It is the time to replace equipments according to long-term use of the system. A pilot system for high speed satellite networks is implemented by seven terminals, three 2-hops and 1 hub in Ku-Band bandwidth by using VSAT. According to the result for the performance test on the system, the result fot all items, including Link Budget designed meets performance levels.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.201-207
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• 2015

Turbine-generator torsional response is caused by interaction between electrical transient air-gap torque and mechanical characteristics of turbine-generator shafts. If torsional shaft torque exceeds a certain threshold, the loss of fatigue life may occur and, in the end, it is possible to happen permanent shaft failure. Therefore, it is required to understand the torsional response for reliable operation and protection of turbine-generator shaft system. In this paper, we introduced multi-mass modeling method of turbine-generator shaft system using mechanical-electrical analogy and state-space equation to verify the transient torsional response based on ElectroMagnetic Transient Program (EMTP). These simple realization methods for turbine-generator shaft torsional response could be helpful to understand torsional interaction phenomena and develop the transient torque reduction countermeasures for turbine-generator shaft system.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.62-68
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• 2014

Composite repair methods besides welding methods such as surfacing and sleeve welding have been used as repair of damaged gas pipelines in foreign countries. Importance of safety management of city gas pipelines have been emphasized recently and our own repair manuals and codes for repair of city gas pipelines are required. It is right time to conduct research on the composite repair methods since the composite repair was introduced rather recently compared to the welding repair methods which have been investigated for long time. In this study, as a starting point of safety assessment of gas pipeline repaird by composite materials, structural analysis of gas pipeline repaired by carbon fiber composite materials was conducted using finite element analysis(FEA) method and the results was discussed.