• Journal of Magnetics
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• 제8권3호
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• pp.124-127
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• 2003

HDDR (hydrogenation, disproportionation, desorption, recombination) and mechanical milling processes have been applied to the $SmCo_{5}$ alloy in an attempt to produce a highly coercive powder. The $SmCo_{5}$ alloy had very high structural stability under the hydrogen atmosphere and the 1:5 phase was only partially disproportionated under up to 10 kgf/$\textrm{cm}^2$ hydrogen gas. The partially disproportionated material was recombined not into 1:5 phase after the HDDR, but rather into multi-phase mixture consisting of 1:5, 2:17, 2:7 and 1:7 phases. The $SmCo_{5}$ alloy HDDR-treated with hydrogen up to 10 kgf/$\textrm{cm}^2$ had poor coercivity. For a useful HDDR to prepare a high coercivity $SmCo_{5}$ alloy powder, much higher hydrogen pressure well exceeding 10 kgf/$\textrm{cm}^2$ would be required. The $SmCo_{5}$ alloy lump was amorphized by an intensive mechanical milling, and it was crystallised ultra-finely by a subsequent optimum annealing. The optimally annealed material had very high coercivity, and it was found that the mechanical milling followed by an annealing was an effective way of producing highly coercive $SmCo_{5}$ alloy powder.

• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.3993-3997
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• 2012

Three-dimensional porous nickel foam was used as a current collector to prepare a Co-Ni oxide/Ni foam electrode for a supercapacitor. The synthesized Co-Ni oxide was proven to consist of mixed oxide phases of $Co_3O_4$ and NiO. The Co-Ni oxide/Ni foam electrode prepared was characterized by morphological observation, crystalline property analysis, cyclic voltammetry, and impedance spectroscopy. Cyclic voltammetry for the electrode showed high specific capacitances, such as 936 F $g^{-1}$ at 5 mV $s^{-1}$ and 566 F $g^{-1}$ at 200 mV $s^{-1}$, and a comparatively good cycle performance. These improved results were mainly due to the dimensional stability of the nickel foam and its high electrical contact between the electrode material and the current collector substrate.

• 한국분말재료학회지
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• 제8권1호
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• pp.55-60
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• 2001

Mechanical alloying technique was applied to prepare hard magnetic $Sm_2Fe_{17}N_x$ compound powders. Staring from pure Fe and Sm powders, the formation process of hard magnetic $Sm_2Fe_{17}N_x$ phase by mechanical alloying and subsequent solid state reaction was studied. As milled powders were found to consist of Sm-Fe amorphous and $\alpha$-Fe phases in all compositions of $Sm_xFe_{100-x}$(x = 11, 13, 15, 17). The effects of starting composition on the formation of $Sm_2Fe_{17}$ intermetallic compound was investigated by heat treatment of mechanically-alloyed powders. When Sm content was 15 at.％, heat-treated powders consisted of nearly $Sm_2Fe_{17}$ single phase. For preparation of hard magnetic $Sm_2Fe_{17}N_x$ powders, additional nitriding treatment was performed under $N_2$ gas flow at 45$0^{\circ}C$. The increase in the coercivity and remanence was proportional to the nitrogen content which increased drastically at first and then increased gradually as the nitriding time was extended to 3 hours.

• 한국건설관리학회논문집
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• 제8권4호
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• pp.73-80
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• 2007

2005년부터 사회기반(SOC)시설에 대한 높은 수준의 공공서비스 제공과 필요시설 조기 확충의 일환으로 미국 등의 PFI(Private Finance Initiative)사업을 벤치마킹한 BTL(Built-Transfer-Lease) 민간투자사업이 국내에 도입되면서, 사업초기 재정투자사업 대비 민간투자사업에 대한 적격성 조사(VFM : Value for Money)의 필요성이 부각되었다. 이에 BTL 사업현황을 분석하고 실무자 입장에서 바라본 사업추진단계별 경제성 분석 방식(VFM분석, 추정사업비 산출, 입찰가격평가 등)의 적정성, 개선필요성 및 대안을 분석해보고자 설문조사를 실시하였다. 실무자 직군별, BTL사업 추진단계별, 개선대안별 교차분석과 상관관계분석 등을 수행한 결과, 사업비용 대비 표준화된 서비스 수준과 운영비 산출 및 평가 기준이 마련되어야 하며, 투자 적격성 조사의 정량적 분석(LCC분석)에 대한 필요성을 토대로 운영관리비, 유지관리비 산출 근거도 마련되어야 한다. 또한 업무의 효율화를 위하여 국내 BTL환경을 고려한 신뢰성 있는 경제성 평가 시스템이 구축되어야 하겠다.

• 한국운동역학회지
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• 제14권3호
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• pp.135-147
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• 2004

This study was conducted to investigate the technical factors of Lu Yu Fu vault actually performed by three men gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu through the DLT method of three dimensional cinematography. To analyze these vaults, the instant events of Lu Yu Fu were set in the board touchdown(BTD), the board takeoff(BTO), the horse touchdown(HTD), the horse takeoff(HTO), the peak height(PH), the mat touchdown(MTD) respectively and the phases of that vault were set in the board contact(BC), the preflight(PRF), the horse contact(HC), the postflight(POF), the grounding on mat(GM) respectively After calculating the performance times, the CG displacement velocity, the kinetic energy impulse reaction force moment arm torque at the horse, the released angle piked angle addressed angle, the angular momentum angular velocity of whole body in x axis, and the horizontal displacement between the feet and CG, the following conclusions were reached. To perform the better Lu Yu Fu vault, a gymnast must have the large horizontal velocity of whole body with fast run-up, decrease the duration time and the horizontal vertical displacement of whole body in PRF, have the enough time to judge the correct magnitude and direction of force to brake or push the horse so as to lengthen the HC duration time at any cost. Also it is desirable to increase the horizontal vertical displacement of whole body in POF if possible, maintain the adequate piked position to decrease the angular velocity of whole body in x axis, prepare the grounding on mat previously and delay the release of the hand from the body to keep the angular momentum.

• 한국환경보건학회지
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• 제44권2호
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• pp.124-132
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• 2018

Objectives: All enterprises intending to install and operate hazardous chemical handling facilities should prepare an off-site risk assessment (ORA) report that evaluates the impact of potential chemical accidents on the surrounding environment and population. This study was conducted to introduce the process of development and the functioning of the Korea Off-site Risk Assessment support tool (KORA) developed by the National Institute of Chemical Safety and to suggest manners to increase its utilization. Additionally, this article provided an overview of KORA. Methods: In order to identify problems with and refinements for KORA, the required items for each phase of KORA were derived by analyzing the Chemical Control Act and related administrative regulations. Results: The functions of KORA made receptor-considered assessment of chemical accidents possible, but several limitations were found in particular phases, such as the analysis of impact range, consideration of sensitive receptors, and assessment of environmental receptors. Conclusion: In this study, we suggested manners to increase the utilization of KORA. It is anticipated that the further research suggested in the study could contribute to the stabilization of the KORA system.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2006년도 춘계학술발표대회 논문집
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• pp.210-214
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• 2006

Along with the development of industrious society, the shape of city and the way of life have changed in accordance. The development of the city deepened gravitation of the city population, leading to the lack of housing and land, and apartment complexes became an alternative way of securing a number of families into a small space of land. Apartment can have a lot of families reside In a small space of land, and it can also be satisfactory to individual's privacy and anti-crime measures. On the other hand, there are negative problems with it. Among them, contacts with neighboring people showed that they only greeted each other when they met in the walkway. As shown in this, one of the reasons that there is a lack of friend ship activities is because there is short of space for common use. And in comparison to those of stairway walkway, apartments with one-passage walk way showed a higher level of contacts with neighbors. It is assumed that apartments with one-passage walk way have more chances to meet neighbors than do those of stairway walkway. This study analyzed the phases appearing in neighbor relations through investigation of the literature, and presented a coping measure. One solution is to prepare flower beds from the outside of walkway by enlarging the width of the walkway in apartments with one-passage walk way, and providing benches in front of flower beds so that residents can take a rest there. The more often residential people take a rest there, the more frequently they can meet each other. Accordingly this can solve problems of contacts with neighbors and the dreary scene of walkway can become a wider view in a nature friendly environment, bringing them to an active acquaintance activities.

• 한국건설관리학회논문집
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• 제9권6호
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• pp.204-215
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• 2008

리모델링 공사는 신축공사와 달리 철거공사가 주공정으로 선행되어야 하는데 현행 철거공사는 개략적 수준의 철거관리계획에 의한 생산성만을 강조한 철거 형태로 인해 폐자재 재활용이 되지않고 있어 자원낭비, 환경파괴를 가중 시키고 있으며, 철거작업 중 작업자의 안전과 구조체의 안전등이 전혀 고려되지 않고 철거하는 것이 현실이다. 따라서 친환경 철거공사가 되기 위해서는 프로세스의 개선이 우선 되어야하며 그 단계를 1) 철거관련 조사분석, 2) 철거관리 도서작성, 3) 철거관리 시공계획서작성, 4) 철거시공 및 감리, 5) 철거 후 관리의 5단계로 구분 하였으며, 특히 철거도면 작성으로 표준철거 WBS가 구축되고, 철거장비 및 공법, 폐기물 투하, 철거공정계획 수립이 가능하며 마감재 철거 후 구조체의 안전점검을 실시하므로써 철거중 불가피한 보수보강이 가능하며, 철거완료 Check list 작성에 따라 리모델링 본공사의 Database 활용이 가능하게 되었다. 본 논문에서는 현행리모델링 철거공사 프로세스(AS-IS)의 문제점을 분석하고 개선된 친환경 리모델링 철거공사 프로세스(TO-BE)를 IDEF0 모델을 사용하여 제안하고자 한다.

• 한국항만경제학회지
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• 제17권2호
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• pp.139-166
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• 2001

Globalization and regionalization are major trends in the international economic system. The severe competition among countries has signalled the need for a new international trade system as prescribed by the WTO, which regulates international trade practices. Additionally, expanding the activities and role of the Pan-Yellow Sea area in the world has a very important function in terms of regional cooperation and logistics environment. In this paper, the trading conditions and shipping transport problems of the Pan-Yellow Sea area (North-East Asia) were investigated. Shipping transport conditions in the Pan-Yellow Sea area, particularly Korea-China routes, were surveyed as well. A new Incheon-China container liner route was suggested as a partial remedy to some of the shipping transport problems of the Pan-Yellow Sea Area (North-East Asia). The Incheon-China Container Liner route is more efficient than Pusan and Pyungtaek Ports or the car ferry route to China in terms of transport time and expense. The transport burden indicator which includes the time and expense of transport, can be a useful tool in comparing these routes. Accordign to the transport burden indicator, the Incheon-China Container Liner route is more efficient than the Pusan, Pyungtaek, or car ferry routes. To establish a successful liner route between the ports of Inchon and China, there is a need to prepare three measures that contain short-term medium-term and long-term strategies. Furthermore, these measures should be prepared and adopted in phases, in accordance with considerations of future conditions for shipping and logistics in the Pan-Yellow Sea area.

• Journal of Pharmaceutical Investigation
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• 제40권4호
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• pp.245-250
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• 2010

Porous poly(lactic-co-glycolic acid) microspheres (PLGA MS) have been utilized as an inhalation delivery system and a matrix scaffold system for tissue engineering. Here, gelatin (type A) is introduced as an extractable pH-responsive porogen, which is capable of controlling the porosity and pore size of PLGA microspheres. Porous PLGA microspheres were prepared by a water-in-oil-in-water ($w_1/o/w_2$) double emulsification/solvent evaporation method. The surface morphology of these microspheres was examined by varying pH (2.0~11.0) of water phases, using scanning electron microscopy (SEM). Also, their porosity and pore size were monitored by altering acidification time (1~5 h) using a phosphoric acid solution. Results showed that the pore-forming capability of gelatin was optimized at pH 5.0, and that the surface pore-formation was not significantly observed at pHs of < 4.0 or > 8.0. This was attributable to the balance between gel-formation by electrostatic repulsion and dissolution of gelatin. The appropriate time-selection between PLGA hardening and gelatin-washing out was considered as a second significant factor to control the porosity. Delaying the acidification time to ~5 h after emulsification was clearly effective to make pores in the microspheres. This finding suggests that the porosity and pore size of porous microspheres using gelatin can be significantly controlled depending on water phase pH and gelatin-removal time. The results obtained in this study would provide valuable pharmaceutical information to prepare porous PLGA MS, which is required to control the porosity.