• International Journal of Air-Conditioning and Refrigeration
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• 제11권1호
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• pp.40-49
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• 2003

Dynamic characteristics of water hammer arresters installed in a building water supply system have been investigated numerically by utilizing a commercial code that employs the method of characteristics. Some preliminary results with those arrester models produced in this study agree well with the previously reported. Then, the arrester models have been incorporated into a water supply pipe system of a 59 $m^2$apartment unit constructed by a leading construction company, and their dynamic characteristics have been investigated, especially on the reduction in the water hammer pressure. It is found that the setting of the arresters in the pipe system, which is recommended by the company, may not be proper for reducing the pressure down below 1,082.0 kPa (10.0 kg$g_f$/$cm^2$) when quick-closure valves in the pipe system are closed within 30 ms at the static pressure of 542.6 kPa (4.5 kg$g_f$/$cm^2$). More arresters in the system may be required to meet pressure criteria stated on the related standards and codes.

• 대한임베디드공학회논문지
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• 제19권3호
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• pp.141-149
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• 2024

This paper proposes a configuration automation technique to minimize service interruption time in the event of a corporate network access layer switch failure. The automation is achieved without the need for a separate external system, as the network setting information is stored in a container inside the switch, enabling rapid recovery without requiring separate storage. This approach ensures the continuity of network services and demonstrates the efficiency of configuration automation. The proposed technique improves corporate network stability by providing a quick response in the event of a failure.

• 대한임상검사과학회지
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• 제37권1호
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• pp.47-55
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• 2005

These studies were done to know decalcification methods to reduce the time of decalcification for quick bone tissue diagnosis. When bone tissue was decalcified with 10 % formic acid at room temperature, decalcification and hematoxylin & eosin (H&E) stains were complete and satisfactory after 12 hours, but some of the tissue sections fell off during staining. In this way, decalcification, H&E stains were complete and satisfactory after 24 hours, 36 hours and 48 hours, tissue sections didn't fall off during staining. When bone tissue was decalcified with 10 % formic acid in a $60^{\circ}C$ paraffin oven, decalcification and H&E stains were complete and satisfactory after 6 hours, but some tissue sections fell off during staining. In this way, decalcification and tissue sections were complete, with no falling off during staining after 8 hours, 10 hours, 12 hours, 14 hours, 24 hours, or H&E stains were satisfactory from 8 hours to 12 hours, but H&E stains appeared to reddish nucleus after 14 hours and 24 hours. Bone tissue was decalcified with 10 % formic acid for 6 hours, 12 hours and 24 hours at DECAL machine frequencies of 15 Hz and 45 Hz, and for 6 hours, 12 hours and 24 hours at a DECAL machine frequency of 90 Hz. Decalcification and H&E stains were complete and satisfactory after 6 hours at the 15 Hz and 45 Hz DECAL settings. Some of the tissue sections fell off during staining at the 15 Hz DECAL machine setting. At the 90 Hz setting, decalcification, H&E stains, and tissue sections were complete and satisfactory with no falling off during staining after 4 hours. In this way, decalcification, H&E stains, and tissue section were complete and satisfactory with no falling off during staining after 12 hours, 24 hours at all machine settings. Bone tissue was decalcified with 10 % formic acid for 6 hours, 12 hours and 24 hours at $37^{\circ}C$ 3 hours, 6 hours and 12 hours at $45^{\circ}C$ and 1 hours, 5 hours and 10 hours at $60^{\circ}C$ with the RHS-1 machine setting at 60Hz. At the temperatures of $37^{\circ}C$, $45^{\circ}C$, and $60^{\circ}C$ decalcification, H&E stains, and tissue sections were complete and satisfactory, with no falling off during staining except for after 6 hours at $37^{\circ}C$. 3 hours, 1 hours, or decalcification, H&E stains, and tissue sections were complete and satisfactory with no falling off during staining after 12 hours and 24 hours at $37^{\circ}C$, 6 hours and 12 hours at $45^{\circ}C$, and 5 hours at $60^{\circ}C$. But H&E stains appeared to reddish nucleus after 10 hours at $60^{\circ}C$. From the above reults, the authors were able to deduce that decalcification is accelerated by heat and frequency. We therefore think that it is necessary for machines which are similar to the RHS-1 machine to be maintained at the temperature evenly with agitation effect for quick decalcification.

• 대한안전경영과학회지
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• 제12권4호
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• pp.117-125
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• 2010

Today, many companies have introduced an ERP system - an enterprise resources planning - in order to improve corporate credibility through transparent management and for quick responses to market situations through quick decision making. After the construction of an ERP system, many companies are having difficulty in calculating the appropriate number of personnel required for running the system because of a lack of standard for doing so, as well as a lack of pertinent procedures. As a result, the companies are having to resort to a trial-and-error approach. Therefore this paper studied a model for calculating the appropriate number of personnel required for efficiently running an ERP system after its construction, as well as for constantly meeting its performance targets. The developed model was applied empirically to calculate an appropriate number of personnel required, and an organization was set up according to this. Therefore, the purpose of this study was to present an optimized model for calculating the number of personnel required for operating an ERP system, that which addresses problems of existing models, in order to help companies organize the operation personnel and its size, as well as to provide more objectivity to the calculated number of personnel required and to improve credibility.

• 한국건축시공학회지
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• 제16권1호
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• pp.1-7
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• 2016

본 연구에서는 $-5^{\circ}C$이하에서도 가열 양생이 없이 수화 반응시 수화열이 높게 발생되는 환원슬래그를 시멘트 분체와 치환사용 하여 영하의 온도에서도 콘크리트의 자체 발열로 인해 압축강도를 재령 3일 이내 5MPa를 발현시켜 초기동해를 방지시키는 것이 최종 연구의 목적이며 이에 대하여 환원슬래그의 물리적 특성 평가와 열적 특성 평가를 실시한 결과 환원슬래그는 높은 수화열을 발생시키기 때문에 저온에서도 압축강도 발현이 우수함을 알 수 있었다. 이는 환원 슬래그의 성분 중 $C_{12}A_7$과 $C_3A$에 의해 수화열이 높게 발생됨 저온에서도 압축강도가 발현되는 것으로 나타났다. 하지만 환원슬래그 단독 치환하였을 경우 $SO_3$함량 부족으로 급결이 발생하는 것을 알 수 있었다. 급결을 방지하기 위해서는 석고의 사용이 필수적으로 사용되어야 한다. 따라서 본 연구 결과 환원슬래그와 석고를 3성분계로 사용하였을 경우 저온에서도 재령 3일에서 5MPa 압축강도를 나타나는 것으로 보아 저온에서도 콘크리트의 초기동해를 방지할 수 있을 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1066-1069
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• 2004

Recently the monitoring system of tool setup in high speed precision machining tool is required for manufacturing products that have highly complex and small shape, high precision and high function. It is very important to reduce time to setup tool in order to improve the machining precision and productivity and to protect the breakage of cutting tool as the shape of product is smaller and more complex. Generally, the combination of errors that geometrical clamping error of fixing tool at the spindle of machining center and the asynchronized error of driving mechanism causes that the run-out of tool reaches to 3∼20 times of the thickness of cutting chip. And also the run-out is occurred by the misalignment between axis of tool shank and axis of spindle and spindle bearing in high speed rotation. Generally, high speed machining is considered when the rotating speed is more than 8,000 rpm. At that time, the life time of tool is reduced to about 50％ and the roughness of machining surface is worse as the run-out is increased to 10 micron. The life time of tool could be increased by making monitoring of tool-setting easy, quick and precise in high speed machining center. This means the consumption of tool is much more reduced. And also it reduces the manufacturing cost and increases the productivity by reducing the tool-setup time of operator. In this study, in order to establish the concept of tool-setting monitoring the measuring method of the geometrical error of tool system is studied when the spindle is stopped. And also the measuring method of run-out, dynamic error of tool system, is studied when the spindle is rotated in 8,000 ∼ 60,000 rpm. The dynamic phenomena of tool-setup is analyzed by implementing the monitoring system of rotating tool system and the noncontact measuring system of micro displacement in high speed.

• 한국운동역학회지
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• 제18권3호
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• pp.93-105
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• 2008

본 연구는 스타팅 블록 유형에 따른 운동학적 변인을 분석하기 위하여 남자 단거리 선수 8명을 대상으로 스타팅 블록간의 거리를 세 가지(25cm, 40cm, 35cm)유형으로 구분하여 분석하였다. 본 연구에 참여한 평균 신장 180cm의 선수들에게는 출발선과 앞 블록의 거리 45cm, 블록간의 거리 40cm의 출발 유형이 100m 기록 단축을 위해서 유리한 스타팅 블록의 유형이라 할 수 있다. 이상의 결론을 종합해보면 100m 출발은 정지 상태에서 짧은 시간에 가능한 큰 추진력을 얻는 데 있으며, 중요한 기술적 요점은 출발 신호에 재빠르게 반응하고, 강한 킥에 의해 큰 추진력을 얻어 전경각과 중력을 잘 이용하여 빠른 시간 내에 최고의 속도에 도달하는데 있다. 본 연구에서는 B유형의 출발법이 기록 향상을 위해 효과적인 분석 결과를 보여주고 있다.

• 한국세라믹학회지
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• 제49권5호
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• pp.442-447
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• 2012

This study investigated on the early hydration and physical characteristics of BFS by pH variation. NaOH solution was used as a pH activator. In the range from pH 12 to pH 14, Experiment was compared the hydration propertied of OPC(Ordinary Portland Cement) and BFS(Blast Furnace BFS) and BFS containing 2 wt% of gypsum. It was found that CAH(Calcium Aluminate Hydrates) phases and CSH(Calcium Silicate Hydrates) phases were formed during the early hydration of BFS, and that CAH phases, CSH phases and ettringites were formed during the early hydration of BFS containing 2 wt% of gypsum. Furthermore, early hydration of BFS and BFS containing 2 wt% of gypsum were faster then OPC at pH 14, and the 1 day compressive strength of BFS increased by approximately 30% compared to OPC, and BFS containing 2 wt% of gypsum also increased by approximately 40% compared to OPC.

• 한국디지털건축인테리어학회논문집
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• 제12권4호
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• pp.5-12
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• 2012

In this study, a digital design process by utilizing the program's database functionality in BIM, public education facilities master plan presented an alternative model to the layout of the design process. First of all, public education facilities master plan design process with digital design process and how to use the database of BIM in the process for review of the possibility of. Secondly, public educational facility planning the placement as needed for the switch to digital design limits, and the basic plan design at various elementary school planning alternatives in a school building and the school site is required to investigate. Thirdly, as a way of using the database features of GDL BIM lnn and teachers on how to create a variable by setting up a number of different alternatives so that you can choose the architect thought to have to organize and visualize the possibility of quick. A quantitative way the basic plan design that repeats some of the measures that can be used for digital design change as a process of continuous research is needed.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.382-394
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• 1988

Dynamic characteristics of thermally-forced stratification process in a square enclosure with a linear temperature profile at the side walls have been investigated through flow visualization experiment and numerical analysis. The experiment was performed on air with the Rayleigh numbers of order $10^5$. A particle tracer method is used for the flow visualization and to obtain a sudden linear temperature profile at the side walls copper blocks which already have a linear temperature profile are come into contact with the thin copper plates of the test section. Immediately a meridional circulation is developed and heat transfer takes place from the wall to the interior region by circulation of fluid and finally a thermal stratification is achieved. In the numerical study, QUICK scheme for convective terms, SIMPLE algorithm for pressure correction, and the implicit method for the time marching are adopted for the integration of conservation equations. Comparison of flow visualization and numerical results shows that the developing flow patterns are very similar in dynamic nature even though there is a time lag due to the inevitable time delay in setting up a linear temperature profile. For high Rayleigh numbers, the oscillatory motion is likely to take place and stratified region is extended. However, initial temperature adjustment process is much slower than that for low Rayleigh numbers.