• 한국정밀공학회지
• /
• 제21권7호
• /
• pp.46-52
• /
• 2004

The Magnetorheological fluid has the properties that its viscosity has drastic changed under some magnetic fields therefore, Magnetorheological fluids has been used fur micro polishing of the micro part(for example, a spherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorheological finishing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fluid are brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate for glass polishing lends support the validity of the approach.

• Journal of Mechanical Science and Technology
• /
• 제19권12호
• /
• pp.2263-2269
• /
• 2005

The ship wave phenomena in the restricted waterway were investigated by a numerical analysis. The Euler and continuity equations were employed for the present study. The boundary fitted and moving grid system was adopted to enhance the computational efficiency. The convective terms in the governing equations and the kinematic free surface boundary condition were solved by the Constrained Interpolated Profile (CIP) algorithm in order to solve accurately wave heights in far field as well as near field. The advantage of the CIP method was verified by the comparison of the computed results by the CIP and the Maker and Cell (MAC) method. The free surface flow simulation around Wigley hull was performed and compared with the experiment for the sake of the validation of the numerical method. The present numerical scheme was applied to the free surface simulation for various canal sections in order to understand the effect of the sectional shape of waterways on the ship waves. The wave heights on the side wall and the shape of the wave patterns with their characteristics of flow are discussed.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 추계 학술논문 발표대회
• /
• pp.114-115
• /
• 2019

Gangform is used as exterior wall forms in the most of apartments. Existing system forms developed for high-rise building, RCS and ACS, are too heavy and over-designed to be applied to general apartments, leading to higher costs. A more simplified rail Gangform(R/GF) is also used, but it depends entirely on T/C for the lift like Gangform. The T/C's legal inactivity time for moving Gangform and materials has increased, and the higher allowances have to be paid for overtime work, thus causing to the cost increase and time delay. Therefore, this study aims to develop an automated Gangform climbing system that can be used universally and economically in apartment houses. The use of the development system is expected to improve the safety of Gangform operations and reduce the workload on T/C.

• 감성과학
• /
• 제25권1호
• /
• pp.67-78
• /
• 2022

ICT 산업의 글로벌 시장을 선점할 수 있는 다음 세대의 개발이 필요한 상황이 일어남에 따라 웨어러블 디바이스의 생체 신호 모니터링에 대한 관심이 크게 증가하고 있다. 이에 따라 본 연구에서는 히스테리시스가 적은 E-Band를 사용하여 단일벽 탄소나노튜브(SWCNT) 분산 용액에 함침 공정을 통해서 저항형 직물 인장 센서(Resistive textile strain sensor)를 개발하였다. 전기전도성이 부여된 e-band에 저항 신호를 측정하기 위해 만능재료시험기(UTM)과 Microcontroller unit인 아두이노와 LCR 미터를 이용해서 인장의 변화에 따른 저항 변화를 측정하였다. 원단으로 이루어진 텍스타일 스트레인 센서의 특성상 발생하는 다양한 노이즈들을 효과적으로 처리하기 위하여 신호처리 과정(Signal processing)의 노이즈 필터링의 이동평균 필터, 사비츠키-골레이 필터, 중앙값 필터들을 사용하여 센서의 필터 성능을 평가하였다. 그 결과 이동평균 필터의 필터링 결과의 신뢰도가 최소 89.82%, 최대 97.87%으로 이동평균 필터링이 텍스타일 스트레인 센서의 노이즈 필터링 방식으로 적합하였다.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제14권1_2호
• /
• pp.1-21
• /
• 1992

In order to find the causes of velopharyngeal incompetency after primary palatorrhaphy in cleft patients, we analyzed the form and function of the velopharyngeal space of fifteen operated cleft palate patients and five normal subjects. The velopharyngeal function was evaluated by lateral cephalometric radiography, velopharyngography and hypernasality cul-de-sac test. The obtained results were as follows. 1. The rate of velopharyngeal incompetency was twenty percent, three of the fifteen operated patients. Two of them were complete cleft palate and the other was incomplete one. 2. The length of soft palate and levator eminence were longer in normal group than those of good speech group and complete cleft palate group during phonation of /i/ (P<0.05). The lengthening rate of soft palate was smaller in good and poor speech group than that of normal group(P<0.05), and, reduced in order, normal group, complete cleft palate group and incomplete palate group(P<0.05). 3. The nasopharyngeal distance had no significant difference between all groups at rest, but, smaller in normal group than that of both cleft palate group(P<0.05), good speech group and poor speech group(P<0.05) during phonation of /i/ The difference in nasopharyngeal distance between rest and /i/ phonation was greater in normal group than that of both cleft palate group, good speech group and poor speech group. 4. The moving distance of sop palate reduced in order, normal group, incomplete cleft palate group, complete cleft palate group(P<0.05). 5. The distance between lateral pharyngeal wall had no significant difference between all groups in rest, but, smaller than that of complete cleft palate group in normal group(P<0.01) and increased in order normal group, good speech group, poor speech group(P<0.01) during phonation of /a/. The mobility of lateral wall was reduced in order, normal group, good speech group poor speech group(P<0. 01). 6. There was low corelationship between the mobility of lateral pharyngeal wall and soft palate. Therfore, it suggest that the movements of lateral pharyngeal wall and soft palate occurs independently.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
• /
• pp.393-397
• /
• 2001

The innovatory process, that is the direct separation and recovery of the iron and zinc metals contained in the high temperature exhaust gas generated from the electric arc furnace fer the inn scrap melting and/or the dust treatment, has been proposed. This proposed process consists of the moving coke bed filter that is directly connected to the electric furnace, and the following heavy metal condenser. The exhaust gas passes through the filter and the condenser right after exhausting from the electric furnace. The moving coke bed filter is being controlled at about 1000℃ and collects iron and slag components contained in the high temperature exhaust gas. Heavy metals such as zinc and lead pass through the filter as vapor. Based on the thermodynamic considerations, the iron oxide and the zinc oxide are reduced in the filter. The solution loss reaction rate is comparatively low at about 1000℃ in the coke bed filter by the analysis using the mathematical simulation model. The heavy metal condenser is installed in the position after the coke bed filter, and rapidly cools the gas from about 1000℃ to 450℃ by a full of the cooling medium like the solid ceramic ball in addition to the cooling from the wall. The zinc and lead vapor condense and separate f개m the gas in a liquid state. The investigation of the characteristics of the exhaust gas of the commercial electric arc furnace, the fundamental experiments of the laboratory scale and the bench scale ensured the formation of this proposed process. A small-scale pilot plant examination is carrying out at present to confirm the formation of the process. It is certain that the dust generation of the electric arc furnace is extremely decreased, and it can save the energy consumption of usual dust treatment processes by the realization of this process.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
• /
• pp.713-721
• /
• 2004

Variable air intake and variable exhaust nozzle of hypersonic engines are designed and tested in this study. Dimensions for variable geometry air intake, ram combustor and variable geometry exhaust nozzle are defined based on the requirements of a pre-cooled turbojet engine. Hypersonic Ramjet Engine is designed as a scaled test bed for each component. Actuation forces of moving parts for variable intake and variable nozzle are reduced by balancing the other force in the opposite direction. A demonstrator engine which includes variable intake and variable nozzle is designed and the components are fabricated. Composite material with silicone carbide is applied for high temperature parts under oxidation environment such as leading edge of the variable intake and combustor liner. Internal cooling structure is adopted for both moving and static parts of the variable nozzle. Pressure recovery and mass capture ratio of the variable intake at Mach 5 is obtained by a hypersonic wind tunnel test. Flow characteristics of the variable nozzle are obtained by a low temperature flow test. Wall temperature and heat flux of the nozzle at Mach 3 is obtained by a firing test. As results, the intake and the nozzle are proved to be used at designed pressure and temperature environment.

• 한국지반공학회논문집
• /
• 제40권2호
• /
• pp.65-79
• /
• 2024

본 연구는 전통적인 통계기반 ARIMA(Auto-Regressive Integrated Moving Average) 모델과 딥러닝 기반 LSTM(Long Short-Term Memory) 모델을 활용하여 굴착 현장의 지중경사계 데이터를 통한 흙막이 벽체 변형을 예측하고, 두 모델의 예측 성능을 비교 분석하였다. ARIMA 모델은 시간의 흐름에 따른 시계열 데이터의 선형적 패턴을 분석하는 데 강점을 보이는 반면, LSTM은 데이터의 복잡한 비선형 패턴과 장기 의존성을 포착하는 데 우수한 능력을 보여주었다. 본 연구는 흙막이 벽체 변형 예측을 위해 지중경사계 계측 데이터에 대한 전처리, 다양한 시계열 데이터 길이 및 입력변수 조건 등에 따른 성능 평가를 포함하였으며, LSTM 모델이 ARIMA 모델에 비해 통계적으로 유의미한 예측 성능 향상을 확인하였다. 본 연구의 결과는 굴착 현장에서의 지중경사계 데이터를 활용한 흙막이 벽체의 안정성 평가에 LSTM 모델을 효과적으로 적용할 수 있음을 보여준다. 또한 이를 바탕으로 향후 굴착 현장 전체에 대한 안전모니터링 시스템 구축과 시계열 예측 모델 발전에 기여할 것으로 기대된다.

• 대한기계학회논문집B
• /
• 제27권10호
• /
• pp.1464-1471
• /
• 2003

In order to investigate the flows with shock wave in branch, 108$^{\circ}$ elbow and T-junction of the IRWST system of standard Korean nuclear reactor, detail time dependent behaviors of unsteady flow with shock wave, vortex and so on are obtained by numerical method using compressible three-dimensional Navier-Stokes equations. At first, the complex flow including the incident and reflected shock waves, vortex and expansion waves which are generated at the corner of T-junction is calculated by the commercial code of FLUENT6 and is compared with the experimental result to obtain the validation of numerical method. Then the flow fields in above mentioned units are analyzed by numerical method of [mite volume method. In numerical analysis, the distributions of flow properties with the moving of shock wave and the forces acting on the wall of each unit which can be used to calculate the size of supporting structure in future are calculated specially. It is found that the initial shock wave of normal type is re-established its type from an oblique one having the same strength of the initial shock wave at the 4 times hydraulic diameters of downstream from the branch point of each unit. Finally, it is turned out that the maximum force acting on the pipe wall becomes in order of the T-junction, 108$^{\circ}$ elbow and branch in magnitude, respectively.

• 한국농촌건축학회논문집
• /
• 제19권2호
• /
• pp.25-33
• /
• 2017

This study aims to find out the change trend of the existing vacant houses in the small and medium sized farming city. And the using method of those houses is proposed in this paper. Especially to find out the change trend ratio of vacant houses in the case, the historic conservation area - Keumma village is selected as the research target area. To carry out this study, it was surveyed in 2013 when they were not designated as the special area first. And it is reviewed in 2017 when it is designated. The contents of the survey were their use, old age, structure, materials, color, roof of the main building and wall. they were surveyed by direct and interview survey. And thew were analyzed and synthesized. It is concluded that the 142 vacant houses in 2013 were declined 46houses in 2017. It is caused by the government support. And they will be declined continuously. The architectural statues of vacant houses between in 2013 and in 2017 are almost same in it's use, old age, structure, materials, color, roof of the main building and wall. In the use ratio of the vacant houses that of residence is most high, and that of warehouses, commerce are followed in turn. The reason of that statues is moving out is the first and the death of house holder, the difficulty of managing are followed. As the their re-use plan of owners, the selling is the first, constructing new buildings and the renovation them are followed. As the method of their use, re-use, community facilities, managing in the vacant houses bank are proposed. As the vacant houses are the reason of bad elements in the rural landscape in the farm village, the method of its improvement will be carried out.