• 한국산학기술학회논문지
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• 제15권6호
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• pp.3363-3369
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• 2014

최근에 건축물의 실내환경을 쾌적하고 안전하게 유지하는 데 많은 노력이 일어나고 있다. 이러한 가운데 주방에서 주로 사용되는 렌지후드에 따른 환기방식은 많이 채택되고 있다. 이에 따라 다양한 디자인의 렌지후드가 적용되고 있다. 렌지후드는 여러 가지 여건상 프레스 금형으로 제작되어 지는데 중,소량의 생산에는 경제성이 떨어진다. 이러한 문제점을 보완하는 방안이 검토되고 있는 상황에서 코어 변환에 따른 금형개발은 매우 유용하리라 판단된다. 본 연구는 금형의 core를 change core 공법으로 설계하였고, 총 4공정으로 금형제작을 수행하였다. 이런 결과로 생산기간 단축 및 모델변경이 용이한 프레스 금형을 개발하였다. 또한 시제품은 3차원 측정결과 제품 표면의 모든 영역에서 허용오차 범위(${\pm}2.00mm$)로 합격하였다.

• 국제물리치료학회지
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• 제10권1호
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• pp.1717-1724
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• 2019

Background : Several studies have suggested different arguments for the effect of stretching exercises and core muscle exercises on flexibility and balance ability. Objective : To determine the effects of stretching exercises and core muscle exercise on flexibility and balance ability. Design : Quasi experimental research Method : The study applied exercise interventions (three sessions per week for 6 weeks) on 40 subjects. The subjects were divided into stretching and core muscle exerciseing groups to identify the change of flexibility and balance ability. Sit- and- reach test results and hip hyperextension were measured for identifying changes in flexibility, and the Romberg test and Pedalo stabilizer were used for changes in balance ability. Results : Both the stretching exercise and core muscle exercise groups showed a statistically significant increase in flexibility (p<.05). However, the stretching exercise group showed a statistically significant increase in balance ability (p<.05), whereas the core muscle exercise group showed partially statistically significant differences in this par t(p>.05). In the analysis of the differences in the amount of change in flexibility, based on the types of exercise, stretching exercises showed a significant difference (p<.05), whereas a significant difference was not found in the amount of change in balance ability (p>.05). Conclusions : These findings indicate that stretching exercises are the more effective intervention for improving and maintaining flexibility, whereas there is no difference between stretching and core muscle exercises with respect to improving balance ability.

• 한국응용과학기술학회지
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• 제20권1호
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• pp.27-32
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• 2003

The core-shell latex particles were prepared by sequential emulsion polymerization of alkyl methacrylate and styrene(ST) by using an water-soluble initiator(APS) after preparing monomer pre-emulsion in the presence of an anionic surfactant(SDBS). In organic/organic core-shell polymerization, the pre-emulsion method, which minimized required quantity of sulfactant, has been used to increase the conversion rate and the stability of core-shell latex particles as well as to reduce the formation of secondary particle that cause problems of soap-free emulsion during shell polymerization. We used several methods to observe the core-shell structure. The core-shell structure was studied by measuring pH change during hydrolysis by NaOH, glass transition temperature($T_g$) by differential scanning calorimeter(DSC), morphology of latex by transmission electron microscope(TEM) and change of particle size and distribution by a particle analyzer.

• 한국안전학회지
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• 제37권4호
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• pp.129-138
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• 2022

A new method for injecting cooling water into the Korean research reactor (KRR) in the event of beam tube rupture is proposed in this paper. Moreover, the research evaluates the risk to the reactor core in terms of core damage frequency (CDF). The proposed method maintains the cooling water in the chimney at a certain level in the tank to prevent nuclear fuel damage solely by gravitational coolant feeding from the emergency water supply system (EWSS). This technique does not require sump recirculation operations described in the current procedure for resolving beam tube accidents. The reduction in the risk to the core in the event of beam tube rupture that can be achieved by the proposed change in the cooling water injection design is quantified as follows. 1) The total CDF of the KRR for the proposed design change is approximately 4.17E-06/yr, which is 8.4% lower than the CDF of the current design (4.55E-06/yr). 2) The CDF for beam tube rupture is 7.10E-08/yr, which represents an 84.1% decrease compared with that of the current design (4.49E-07/yr). In addition to this quantitative reduction in risk, the modified cooling water injection design maintains a supply of pure coolant to the EWSS tank. This means that the reactor does not require decontamination after an accident. Thermal hydraulic analysis proves that the water level in the reactor pool does not cause damage to the nuclear fuel cladding after beam tube rupture. This is because the amount of water in the chimney can be regulated by the EWSS function. The EWSS supplies emergency water to the reactor core to compensate for the evaporation of coolant in the core, thus allowing water to cover the fuel assemblies in the reactor core over a sufficient amount of time.

• 한국CDE학회논문집
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• 제19권2호
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• pp.103-110
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• 2014

Engineering changes are indispensable engineering and management activities for manufactures to develop competitive products and to maintain consistency of its product data. Analysis of engineering changes provides a core functionality to support decision makings for engineering change management. This study aims to develop a method for analysis of engineering changes based on On-Line Analytical Processing (OLAP), a proven database analysis technology that has been applied to various business areas. This approach automates data processing for engineering change analysis from product databases that follow an international standard for product data management (PDM), and enables analysts to analyze various aspects of engineering changes with its OLAP operations. The study consists of modeling a standard PDM database and a multidimensional data model for engineering change analysis, implementing the standard and multidimensional models with PDM and data cube systems and applying the implemented data cube to core functions of engineering change management, the evaluation and propagation of engineering changes.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.191-194
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• 2004

A novel type of intelligent microcapsule reactor system was prepared. The reactor can recognize pH change in the medea and control reaction rate by itself. For the reactor system, acrylic acid (AA), N-isopropylacrylamide (NIPAM), and glucose oxidase (GOD) were selected as a pH-responsive device, a gating device according and a reaction device, respectively. Poly(NIPAM-co-AA) (P-NIPAM-co-AA) are known to change its hydrophilicity-hydrophobicity due to pH change. They were integrated in a core-shell microcapsule space. GOD was loaded inside the core space and the pores in the outside shell layer were filled with P-NIPAM-co-AA linear grafted chains as pH-responsive gates by plasma graft filling polymerization method. When P-NIPAM-co-AA gates are hydrophilic at high pH value, this microcapsule permits glucose penetration into the core space and GOD reaction proceeds. However, when P-NIPAM-co-AA gates are hydrophobic at low pH value, this microcapsule forbids glucose penetration and GOD reaction will not occur. The accuracy of this concept was examined.

• 전기의세계
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• 제13권2호
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• pp.1-4
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• 1964

Phase transformation is used to change some phase from phase in A.C. system. We have been used Scott or Fork connection in phase transformation the otherwise phase transformation was constructed from M-G set. From this M-G set, we could make phase shift facilities by mannual. Now, I can derive more easy phase transformation from taking another method. I believe this new phase transformation method in the first thing in the world. And so, I am going to explain about phase transformer construction process. The first, we could devide into equal part of core around the iron core as to be same size. The second, you will make primary and secondary winding on the core. The third, when you will supplied three phase A.C. at the terminal of primary winding you can get e.m.f. inducing of some phase at secondary. And so, we could make phase change from some phase A.C. We can apply this principle in many fields, i.e., freequency changer, phase leader of no use condenser, voltage regulator in keeping balance, and D.C. generator. And more, I will introduce in details concerning main pinciple and theory through following chapter.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.772-784
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• 2024

The hexagonal nodal code RENUS has been enhanced to handle irregularly deformed hexagonal assemblies. The underlying RENUS methods involving triangle-based polynomial expansion nodal (T-PEN) and corner point balance (CPB) were extended in a way to use line and surface integrals of polynomials in a deformed hexagonal geometry. The nodal calculation is accelerated by the coarse mesh finite difference (CMFD) formulation extended to unstructured geometry. The accuracy of the unstructured nodal solution was evaluated for a group of 2D SFR core problems in which the assembly corner points are arbitrarily displaced. The RENUS results for the change in nuclear characteristics resulting from fuel deformation were compared with those of the reference McCARD Monte Carlo code. It turned out that the two solutions agree within 18 pcm in reactivity change and 0.46% in assembly power distribution change. These results demonstrate that the proposed unstructured nodal method can accurately model heterogeneous thermal expansion in hexagonal fueled cores.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.1-8
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• 2000

A new method of knock detection in SI engines, using a change of ion concentration in the combustion chamber, was developed. In order to measure in-cylinder ionization current, ionization probes were installed at spark plug and cylinder head of production engine. It was found that the electric current generated by ionized gas in core burned gas region of knocking cycle is between 2 and 10 times larger than that of normal cycle, because the burned gas temperature which is the dominant parameter of a change of ion concentration increases. However, a change of ionization current in boundary region of burned gas is relatively weak. Hence a change of ion concentration in core burned gas region can be used for knock detection.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.591-596
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• 2011

There are quite a number of business processes in the urban regeneration project. Managers and participants who involved in the project make and use information for the best way to perform in the particular business process. The information can be also reused and produced for data at the next stage. Accordingly, the information sometimes goes out of existence and work data up into new information when the urban regeneration project has been accomplished. But in that case some of changes happen occasionally, the business for urban regeneration has suffered a loss of profit and time as result of confusions about decisions and inappropriate action. For that reason, the information should be analyzed to achieve its aim at the business process under the influence of changes. Then, even though detail processes and management method change, the Core Information, which are important factors for accomplishing the project, help that the project can be operated to solve the problem about confusion and loss of the business. In conclusion, the Core Information is main effective factors for successful urban regeneration projects on the change management. The purpose of this study is to research the information according to the Information-flow and changes, and to find out the influence factors and the Core Information to manage efficiently at the process of urban regeneration projects.