• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1019-1022
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• 2002

Pipe-cutting machines have been used in many fields. Recently, an automatic pipe-cutting machine that uses magnet has born developed. In this paper, a magnetic-type automatic pipe-cutting machine that attaches itself and performs unmanned cutting process is proposed. It is designed that there is a room at the bottom of its body to contain a magnet. And it uses magnetic force between the magnet and the pipe surface to prevent slip and to attach the machine to the pipe against gravity. Also the magnetic force is adjustable by changing the gap between the magnet and the pipe. This machine is, however, necessary to control cutting velocity for the elevation of work efficiency and the adjustable faculties. During pipe cutting process, the gravity acting on the pipe-cutting machine widely varies. That is, the cutting machine gets fast when moving from the top to the bottom of the pipe and slow when moving from the bottom to the top. Actually the system is kind of a non-linear system where the gravity is function of climbing angle of the cutting machine along the pipe. Especially jerking motion is critical. Therefore, authors design the non-linear controller that estimates the current position of the machine along the pipe and compensates the effect of gravity in this paper. It receives the feed back signal from the encoder.

• 한국측량학회지
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• 제13권1호
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• pp.49-59
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• 1995

본 연구는 농업용수 개발사업의 기초조사와 기본계획 및 실시설계 과정에 수치지형정보를 활용함으로써 농업용수 개발사업의 경제적이고 합리적인 추진에 기여함을 목적으로 한다. 본 연구에서는 대상지역의 수치지형정보를 취득하기 위해 항공사진을 이용하였으며, 이를 보간하여 대상계획에 적합한 수치표고모형을 생성함은 물론, 관련도형정보 및 속성자료를 이용하여 농업용수 개발사업의 기초조사용 데이터 베이스를 설계하였다 본 연구의 수행결과, 본 연구에서 정 저한 방법이 농업용수 개발사업의 효율적 인 수행에 기여함을 알 수 있었다.

• 대한치과교정학회지
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• 제48권3호
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• pp.200-211
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• 2018

The aim of this systematic review was to evaluate the effectiveness and complications of corticotomy and piezocision in canine retraction. Five electronic databases (PubMed, SCOPUS, Web of Science, Embase, and CENTRAL) were searched for articles published up to July 2017. The databases were searched for randomized control trials (RCTs), with a split-mouth design, using either corticotomy or piezocision. The primary outcome reported for canine retraction was either the amount of tooth movement, rate of tooth movement, or treatment time. The secondary outcome was complications. The selection process was based on the PRISMA guidelines. A risk of bias assessment was also performed. Our search retrieved 530 abstracts. However, only five RCTs were finally included. Corticotomy showed a more significant (i.e., 2 to 4 times faster) increase in the rate of tooth movement than did the conventional method. For piezocision, both accumulative tooth movement and rate of tooth movement were twice faster than those of the conventional method. Corticotomy (with a flap design avoiding marginal bone incision) or flapless piezocision procedures were not detrimental to periodontal health. Nevertheless, piezocision resulted in higher levels of patient satisfaction. The main limitation of this study was the limited number of primary research publications on both techniques. For canine retraction into the immediate premolar extraction site, the rate of canine movement after piezocision was almost comparable to that of corticotomy with only buccal flap elevation.

• 대한조선학회논문집
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• 제42권3호
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• pp.205-211
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• 2005

In this study, a new numerical procedure for the generation of a nonlinear tailored group of waves is presented. The procedure is based on the transient wave group technique. In order to integrate the nonlinearity during the wave propagation in the computational method, the Navier-Stokes equations are applied as governing equations. The governing equations are discretized by finite volume approximation. The deformation of the free water surface in each time step is pursued with a moving grid. A two-dimensional, numerical wave tank for the simulation of the wave propagation is developed and tested in detail. The numeric results are compared first with analytical wave theories and with measurements, in order to examine the correctness of the numerical wave tank. Wave surface elevation and associated fields of velocity and pressure are numerically computed and compared with measurements. Very good agreements show up.

• 한국CDE학회논문집
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• 제14권4호
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• pp.242-253
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• 2009

Nowadays, manufacturing industry has been making its effort not only for productivity elevation but also for cost reduction in order to survive in the global market which is more and more challenging. In this paper, the method for planning of digital manufacturing system is proposed and door trim assembly system is determined as the subject of our research. First of all, the process sequence is generated based on the product analysis. And, the static and dynamic relationships between system components are represented using IDEF0 and UML model. The working time is estimated through the regression analysis based on MODAPTS method. According to the system configuration strategy, initial concept system layout is implemented 3D virtual environment. The problems caused by bad working motions are detected and modified through the ergonomic analysis using RULA method. According to proposed procedure, digital door trim assembly system is implemented in DLEMIA.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.89-96
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• 2008

삼면이 바다로 둘러 싸여 있는 우리나라는 계절풍, 해풍에 의한 염분이 포함된 수분과 중화학공업에 따른 매연, 분진이 배전설비의 표면에 부착되어, 설비의 열화로 인한 정전이 발생할 가능성이 크므로, 염분에 의한 오손등급을 평가하여 설비운영에 활용함으로써, 정전을 예방하고 정전 관련 민원을 최소화할 필요가 있다. 또한, 최근에는 이상 기상 현상으로 인해 과거에 예기치 못한 자연재해가 발생하고 있으므로, 이에 대한 기후조건과 지형자료 등을 바탕으로 새로운 오손분포 산정 알고리즘을 개발하고, 오손분포 도면을 제작하여, 이를 해안지역의 배전설비 설계에 적용하는데 본 연구의 목적이 있다.

• 한국실내디자인학회논문집
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• 제26권1호
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• pp.134-141
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• 2017

General hospitals in Korea have increased more in size since 2000, and as not only medical service but the quality of the environment also got important, the considerable changes have appeared revolving around the lobbies. This study is a basic research to find a direction of a plan for general hospital lobbies in response to the demands that change. It was examined the current condition of lobbies so as to derive the idea of types of lobbies and of functional elements, and based on the research, it was compared and analyzed in terms of the spatial configuration to draw the characteristics by type. The result of the research is as follows. (1) The lobbies were explored after being classified into four types; the plan(central type/street type) and the elevation(eclectic type/double-story type). (2) The hall and corridor were ranked high in order of importance in the whole spatial configuration, and it has been utilized in various ways. (3) Also, each type differed with the others in its main functional area, regarding traffic line efficiency and spatial intelligibility.

• 한국실내디자인학회논문집
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• 제15권1호
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• pp.88-97
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• 2006

The purpose of this study was to provide a guideline for the bathroom fixtures of the aged by examining current status. The study has been carried out by measuring physical size of 50 aged peoples over 65 years old and their bathroom fixture status. The results were revealed as follows; 1. The height of washstand is $0.46\~0.52$ time of person's height. Adequate height of wash stand is proposed as $74\~80$ cm. The height of current market available wash stand is very close to the proposed size. 2. The height of toilet is $0.23\~0.27$ time of person's height. Adequate height of toilet is proposed as $38\~41$ cm. The height of current market available toilet is also very close to the proposed size. 3. The height of bathtub is $0.26\~0.35$ time of person's height. Adequate height of bath tub is proposed as $45\~49$ cm. The proposed height is higher than that of current bath tub available in the market. However, it should be noted that the proposed height is the sum of bath tub it self and elevation during actual installation. As stated above, it is revealed that the physical dimensions of the bathroom fixtures in the current market are properly sized. However, to draw more practical guideline for the bathroom fixture, more studies including actual experimentation will be required in the future.

• Wind and Structures
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• 제31권6호
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• pp.483-493
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• 2020

Large cylindrical floating-roof tanks, constructed as oil containers, are usually distributed regularly in open area and easily exposed to severe wind loads. However, wind pressures around these grouped squat tanks appear to have not been clearly given in design codes or thoroughly studied in existing researches. This paper conducts a detailed investigation on wind loads on the external wall of a four-tank group in square arrangement. To achieve that, wind tunnel tests are carried out on both empty and full tank groups, considering various wind angles and spacing. Results show that 3 regions in elevation can be identified on the tank shell according to the circumferential wind pressure distribution. The upper 2 regions cover a relatively small portion of the shell where excessive negative pressures are spotted, setting an alarm to the design of the top angle and stiffening rings. By comparing results on grouped tanks to those on an isolated tank, grouping effects concerning wind angle, tank position in group and spacing are discussed. Deviations on pressure distributions that will compromise structural safety are outlined, including the increase of negative pressures, the shift of maximum pressure locations as well as the change of positive pressure range. And, several potentially unfavourable wind pressure distributions are selected for further analyses.

• Advances in aircraft and spacecraft science
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• 제9권4호
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• pp.349-366
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• 2022

The ability of baffles in increasing the sloshing damping is investigated in this study by theoretical, numerical, and experimental methods. Baffles Installed as separators in containers, can change the dynamic properties of sloshing. The main purpose of this study is to investigate the effect of baffle placement.The main purpose of this study is to investigate the effect of placing baffles in order to provide appropriate frequencies and damping and to present a practical baffle arrangement in the design ofsloshing. In this regard, an experimental setup is designed to study the fluid sloshing behavior and damping properties in cylindrical tanks filled up to an arbitrary depth. A new combination of annular and sectorial baffles is employed to evaluate fluid sloshing in the tank. The results show that the proposed baffle arrangement has a desired effect on the damping and fluid sloshing frequencies and optimally satisfies the anticipated design requirements. In addition, the theoretical frequencies exceed empirical frequencies at the points far from baffles, while at the points close to baffles, the empirical ones are higher than theoretical ones. Also, at the depths near the bottom of container sloshing frequencies are not affected by sectorial baffles, although the theoretical curve predicts a reduction in the fundamental frequency of sloshing. Finally, the results of finite volume and finite element methods which compared with experimental data, indicated a good agreement between different approaches.