• 대한치과마취과학회지
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• 제12권4호
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• pp.229-233
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• 2012

Severe한 혈우병 B 환아가 소아과에 입원하여 세계혈우병연맹(World Federation of Hemophilia, WFH) 지침서에 따라서 응고인자 수준을 유지하면서 다수의 발치를 포함한 관혈적 치과 치료를 받았다. 이와 같이 혈우병 환자에서 다수의 발치를 시행할 때 주기적인 혈액검사를 통한 응고인자 수준의 관리와 복잡한 의과적 처치가 요구된다. 따라서 다수의 발치가 요구되는 경우 전신마취 하에 가능한 모든 치과치료를 시행하는 것이 효과적이고 효율적인 방법이 될 수 있다.

• 한국생산제조학회지
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• 제22권1호
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• pp.85-91
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• 2013

The machinability of wear-resistible tungsten carbides and the tool wear behavior in machining of V30 and V50 tungsten carbides using PCD (Poly Crystalline Diamond) cutting tool was investigated to understand machining characteristics. This material is one of the difficult-to-cut materials in present, but their usage has been already broadened to every commercial applications such as mining tools, and impact resistant tools etc. Summary of the results are as follows. (1) Tool wear progression of PCD tools in turning of wear-resistible tungsten carbides were observed specially fast in primary cutting distance within 10m. (2) Three components of cutting resistance in this research were different in balance from the ordinary cutting such as that cutting of steel or cast iron. Those were expressed large value by order of thrust force, principal force, feed force. (3) If presume from viewpoint of high efficient cutting within this research, a proper cutting speed was 15m/min and a proper feed rate was 0.1mm/rev. In this case, it was found that the tool life of PCD tool was cutting distance until 230m approximately. (4) In cutting of wear-resistible tungsten carbides such as V30 and V50, it was recognized that the tool wear rate of V30 was very fast as compared with V50. (5) When the depth of cut was 0.1mm, there was no influence of the feed rate on the feed force. And the feed force tended to decrease as the cutting distance was long, because the tool was worn and the tool edge retreated. (6) It was observed that the tungsten carbides were adhered to the flank.

• 에너지공학
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• 제14권2호
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• pp.73-81
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• 2005

강판의 냉간압연 후 소둔을 하기 위한 열처리 공정에서 사용되고 있는 Radiant Tube Burner(이하 RT버너) 연비를 개선하기 위한 효율적인 방법을 실험적으로 조사하였다. 재열기가 설치된 모델 RT버너를 실험에 맞도록 개조하여, 배기 중 산소 농도 조건을 변화시키면서 연료 소모에 대한 흡입공기의 온도와 산소분율의 영향도를 파악하였다. 본 연구의 결과, 흡기 온도를 상승시키면 RT버너의 chamber온도가 상승하나 그 상승폭은 흡기 온도 상승폭의 $10\%$에 지나지 많아, 흡입 공기 온도의 상승만으로는 연료 소모 개선을 기대할 수 없다는 것을 알 수 있었다 그러나, 흡입 공기 중 산소분율 변경 실험 결과, 흡입 공기 중의 산소분율을 $1.5\%$증가시키면 NOx의 배출이 약 $40\%$정도 증가하지만 약 $20\%$의 연비 개선 효과를 보였다. 따라서, NOx 배출 증가를 억제하는 산소 고부하 전용 RT버너는 RT버너 시스템의 연료 소모를 개선하는 효과적인 방법의 하나로 기대된다.

• 전기학회논문지P
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• 제59권1호
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• pp.77-82
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• 2010

This study evaluated the characteristics and reliability of an auger crane with a built-in hydraulic extender. The field test of the hydraulic extender was performed with the hydraulic lines filled with hydraulic fluid and free of air. The pressure generated during the test was measured with a digital pressure gauge. The crane was considered to have undergone one cycle of the excavation process after it had performed excavation under three conditions at the same location. This process was performed three times in total. From the results of the excavation using the hydraulic extender, it was found that the maximum pressure and torque measured were 19.9 [MPa] and 895.4 [$kgf{\cdot}m$], respectively. The rotation force of the auger crane generated at this time signifies a horizontal force. If the excavation diameter of the auger crane is increased, the rotation speed is reduced causing the circumferential speed to also be reduced. The torsional shear stress of the extendable auger crane was calculated to be approximately 23.5 [MPa]. However, the rotation shaft material used for this system was carbon steel for machine structural use (SM45C). Since the minimum torsional yield stress is greater than 150 [MPa] according to KS D 3752, it means the equipment has secured a safety factor greater than 6. Therefore, it was found that when performing work using the extendable auger crane, it exhibited no problems with the safety and reliability of its shaft.

• 한국정밀공학회지
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• 제20권7호
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• pp.233-240
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• 2003

Recently, the world are preparing for new revolution, called as If (Information Technology), NT (Nano-Technology), and BT (Bio-Technology). NT can be applied to various fields such as semiconductor-micro technology. Ultra precision processing is required for NT in the field of mechanical engineering. Recently, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts. Therefore, in this paper, stability of ultra precision cutting unit is investigated, this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material about hinge, stability investigation is performed. In this paper, hinge shapes of micro stage in UPCU(Ultra Precision Cutting Unit) are designed as two types, where, hinge shapes are composed of round and rectangularity. Elasticity and strength are analyzed about micro stage, according to hinge shapes, by FE analysis. Micro stage in ultra precision processing machine has to keep hinge shape under cutting condition with 3-component force (cutting component, axial component, radial component) and to reduce modification against cutting force. Then we investigated its elasticity and its strength against these conditions. Material of micro stage is generally used to duralumin with small thermal deformation. But, stability of micro stage is investigated, according to elasticity and strength due to various materials, by FE analysis. Where, Used materials are composed of aluminum of low strength and cooper of medium strength and spring steel of high strength. Through this stability investigation, trial and error is reduced in design and manufacture, at the same time, we are accumulated foundation data for unit control.

• Steel and Composite Structures
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• 제15권6호
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• pp.585-603
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• 2013

Generally the required strength and stiffness of an I-shaped beam to the box-shaped column connection is achieved if continuity plates are welded to the column flanges from all sides. However, welding the forth edge of a continuity plate to the column flange may not be easily done and is normally accompanied by remarkable difficulties. This study was aimed to propose an alternative for box columns with continuity plates to diminish such problems. For this purpose a double-web I-shaped column was proposed. In this case the strength and rotational stiffness of the connection was provided by nearing the column webs to each other. Finite element studies on about 120 beam-column connections showed that the optimum proportion of the distance between two column webs and the width of the column flange (parameter ${\beta}$) was a function of the ratio of the beam flange width to the column flange width (parameter ${\alpha}$). Hence, based on the finite element results, an equation was proposed to estimate the optimum value of parameter ${\beta}$ in terms of parameter ${\alpha}$ to achieve the highest connection performance. Results also showed that the strength and ductility of post-Northridge connections of such columns are in average 12.5 % and 54% respectively higher than those of box-shaped columns with ordinary continuity plates. Therefore, a double-web I-shaped column of optimum arrangement might be a proper replacement for a box column with continuity plates when beams are rigidly attached to it.

• Structural Engineering and Mechanics
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• 제39권3호
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• pp.427-447
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• 2011

The progressive collapse phenomenon is generally regarded as dynamic. Due to the impracticality of nonlinear dynamic computations for practitioners, an interest arises for the development of equivalent static pushover procedures. The present paper proposes a methodology to identify such a procedure for sudden column removals, using energetic evaluations to determine the pushover loads to apply. In a dynamic context, equality between the cumulated external and internal works indicates a vanishing kinetic energy. If such a state is reached, the structure is sometimes assumed able to withstand the column removal. Approximations of these works can be estimated using a static computation, leading to an estimate of the displacements at the zero kinetic energy configuration. In comparison with other available procedures based on such criteria, the present contribution identifies loading patterns to associate with the zero-kinetic energy criterion to avoid a single-degree-of-freedom idealisation. A parametric study over a family of regular steel structures of varying sizes uses non-linear dynamic computations to assess the proposed pushover loading pattern for the cases of central and lateral ground floor column failure. The identified quasi-static loading schemes are shown to allow detecting nearly all dynamically detected plastic hinges, so that the various beams are provided with sufficient resistance during the design process. A proper accuracy is obtained for the plastic rotations of the most plastified hinges almost independently of the design parameters (loads, geometry, robustness), indicating that the methodology could be extended to provide estimates of the required ductility for the beams, columns, and beam-column connections.

• Steel and Composite Structures
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• 제28권4호
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• pp.439-447
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• 2018

The structural behaviors of cylindrical barns as a specific engineering structure have been considered as a complicated computing process. The structure design against the earthquake load, to protect by using the code, is an urgency avoiding unexpected damages. The situation has been subjected to the applied design method if there would be no failure across the construction procedures. The purpose of the current study is to clarify the behaviors of cylindrical reinforced concrete barns through the analytic methods across the mass and Lagrangian approaches through the whole outcomes comparison indicating that the isoparametric element obtained from the Lagrangian approach has been successfully applied in the barns earthquake analysis when the slosh effects have been discarded. The form of stress distributions is equal with $s_z$ closed distributions to one another.

• 한국멀티미디어학회논문지
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• 제11권10호
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• pp.1376-1384
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• 2008

망의 자동형성에 대한 많은 연구들은 주로 무선 센서 망과 애드혹 망에 대해 수행되었으며 그 결과들은 아직까지 공장자동화에 적용되지 못하였다. 본 논문은 블루투스 통신과 PDA(Personal Digital Assistant)를 이용하여 조업자의 위치에 종속됨 없이 공정 환경을 감시, 제어하는 공정 관리 시스템의 개발에 관하여 기술한다. 이는 유선망을 사용할 수 없는 회전체의 설비진단에 필수적이다. 모바일 단말이 공정관리 서버의 통신 범위에 접근하면 서버는 이동 단말의 존재를 인지하여 스스로 네트워크를 형성한다. 사용자에 대한 인증과정을 거쳐 모바일 단말의 소유자 권한에 따른 모니터링 제어 프로그램을 자동으로 다운로드하여 설치한다. 또한 모바일 단말이 서버의 통신 반경을 벋어나게 되면 네트워크에서 제외하고 프로그램을 자동으로 삭제하여 리소스를 줄이고 모바일 단말의 분실 시 발생할 수 있는 보안상의 문제를 방지한다. 개발된 기능들은 공장 시뮬레이터에서 동작을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.914-919
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• 2008

This present was carried out to evaluate the adaptability of stabilization method which was used industrial byproducts as the stabilization agency in the abandoned mine site. In order to investigate stabilization effect on As-contaminated soils treated by industrial by-products, batch tests and column tests were carried out with As-contaminated soils collected from farmland around the abandoned mine site. ZVI(zero valent iron) and SRS(steel refining slag) was shown a good treatment effect. After the column test, sequential extraction test and simple bioavailability extraction test(SBET) were carried out to analysis of the soil, and scanning electron micrograph(SEM) analysis was carried out to compare the morphology and structure of ZVI and SRS before and after reacting with arsenic in the soil. As a result, ZVI and SRS were shown 93%, 62% reduction of As concentration respectively by comparison with untreated soils. Therefore, if ZVI and SRS are used as treatment materials in As-contaminated soils, it is expected that the As leaching from soils is reduced effectively.