• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.150-152
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• 1994

In this paper, the optimum shape design of stator slot of induction motors for iron loss reduction is proposed. To obtain the flux distribution in induction motors, 2-D finite element method with voltage source is employed. The iron loss is calculated from the iron loss data given by the iron manufacturer. To calculate the sensitivity of iron loss to shape variation, the sensitivity analysis of discrete approach is used. The proposed algorithm is applied to a 3-phase squirrel cage induction motor. The nodes at stator slot boundary of the induction motor are defined as design parameters. By controlling these parameters under the constant volume of iron, we can minimize the iron loss. Furthermore, the stator copper loss is reduced by increasing the slot area. So the stator slot area is determined at the point that the summation of iron loss and copper loss of stator is minimized. Since the constraint of constant volume of iron is nonlinear to the design parameters, the Gradient Projection method is used as an optimization algorithm.

• 한국수산과학회지
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• 제49권6호
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• pp.856-861
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• 2016

This study compared the density of fish determined using three different echogram methods: the frequency-difference, time variable, and threshold modification methods. An acoustic survey was conducted off the coast of Jeju Island after sunset. Data at 38 and 120 kHz frequencies were collected using a commercial fishing vessel. As a reference point, the value of ${\Delta}MVBS_{120-38kHz}$ that distinguished fish from zooplankton using the 38 and 120 kHz frequencies was set at < 2 dB. The estimated density of fish along the survey line was 0.1-30.4, 0.1-64.3, and $0.1-51.7m^2/nmi^2$ using the frequency difference, time variable threshold, and threshold modification methods, respectively. The results of this study constitute basic research for estimating fish densities.

• 대한간호학회지
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• 제35권4호
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• pp.656-663
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• 2005

Purpose. Nursing research is recognized as an essential basis for the continuous development of the scientific nursing knowledge and practice. An understanding of the barriers and attitudes to research among nurses is important to improve clinical nursing research activities. Method. Data were collected from nurses at a general hospital, located in D city, using a self-reported questionnaire, from March 15th to April 4th, 2003, and 133 questionnaires were used for the analyses. A 5 point-scale instrument was used to measure barriers and attitudes towards nursing research, with a Cronbach's alpha of .85 and .89, respectively. Results. Nurses had limited experience in research and were not well prepared to conduct it. Lack of experience, training and time were the major barriers for conducting research. However, the nurses had positive attitudes toward research. There was a difference in barriers (t = 2.68, P = .02) and research attitudes (t =- 2.74, P = .00) according to the nurses' position. Also, the nurses' research experience influenced research attitudes (t = -3.27, P = .00). The degree of research preparation (F = 6.98, P = .00) had an effect on the attitudes toward nursing research but not on the barriers. Conclusion. There is an urgent need to promote both the ability and environment for clinical nurses to actively participate in research. As the majority of nurses had little experience and low confidence in research and perceived many barriers, this promotion can be accomplished by enhancing their confidence in research through continuing education and by gradually eliminating the barriers to research.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.881-888
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• 2017

일반적으로 다단 축류 터빈은 높은 압력비에서 유동 가속으로 인하여 특정 단에서 초킹 현상이 발생하게 된다. 초킹의 경우 유량 변화 없이 압력비만 증가하게 되며, 이러한 특성을 입구 유량 경계조건을 사용하는 일반적인 평균반경해석법을 이용하여 예측하는데 한계가 있다. 본 연구에서는 이러한 문제점을 해결하기 위해 초킹 영역에서의 성능을 예측하는 알고리즘을 재안하였다. 초킹 지점 이후에는 초킹이 발생하는 노즐 혹은 로터 출구 유동이 팽창하는 특성을 반영하여 고정된 유량 조건에서 압력비가 변할 수 있도록 알고리즘을 구성하였다. 이러한 결과를 다단 축류 터빈 전산해석 결과 및 실험결과와 비교하여 신뢰성을 확인하였다.

• 기술혁신학회지
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• 제7권3호
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• pp.607-640
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• 2004

This article analyzes the venture firm based upon the new framework of Dynamic Firm Capability (DFC) to identify the process mechanism. Research methodology includes the case study involving structured interview and data collection from two leading Korean ICT(Information Communication Technology) firms in the same sector (DVR). IDIS, spun off from the university, has accumulated the innovative capability based on the R&D department. On the other hand, KODICOM has retained the technological trajectory in terms of marketing competence. Underlying hypothesis is that a firm should show a idiosyncratic evolutionary pattern by acquiring different complimentary assets(CA). In addition, effective internal process should be matched with the essential characteristics not only at the firm level but also at the sectoral level. By analyzing those two different firms, we will find the strategic successful factors based upon the evolutionary point of view. It is a key contribution of this paper to study on the process mechanism of ventures, and to explain detailed process mechanism by viewing two different characteristics of the firm at the functional level.

• 한국관개배수논문집
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• 제18권1호
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• pp.4-17
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• 2011

The standard design methodology was suggested to construct wetland system for reducing non-point source pollution from Saemangeum reclaimed paddy land. To set for the design flow and concentrations, runoff and water quality survey were conducted during the irrigation period in 2008 at Gyehwa reclaimed paddy land located at near Saemangeum lake. It is rational that 1ha is the optimum constructed wetland size. To meet this size, the moderate drainage area of reclaimed paddy field was 50ha under the conditions that rainfall is 30mm, average runoff coefficient is 0.83, and runoff capture ratio is 0.6. At these condition, the runoff volume from 50ha was 10,520 $m^3/d$ including base flow during irrigation period. To select the optimum wetland system, several case studies were conducted by focusing on the tidal reclaimed land areas having wetland systems in Seokmun. Pond-Wetland system was selected as the standard model because of showing the highest reduction efficiency. Single variable regression equation were delivered to estimate effluent water concentrations from the designed wetland by using long-term monitoring data from the Seokmun experiment site. The effluent concentration from the designed wetland using these equation were showed moderately range.

• 한국추진공학회지
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• 제22권2호
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• pp.20-28
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• 2018

일반적으로 다단 축류 터빈은 높은 팽창비에서 유동 가속으로 인하여 특정 단에서 초킹 현상이 발생하게 된다. 입구 유량 경계조건을 사용하는 일반적인 평균반경해석법을 사용하는 경우 유량 변화없이 팽창비만 증가하게 되는 초킹 현상을 예측하는데 한계가 있다. 본 연구에서는 이러한 문제점을 해결하기 위해 초킹 영역에서의 성능을 예측하는 알고리즘을 제안하였다. 초킹 지점 이후에는 초킹이 발생하는 노즐 혹은 로터 출구 유동이 팽창하는 특성을 반영하여 고정된 유량 조건에서 팽창비가 변할 수 있도록 알고리즘을 구성하였다. 계산된 결과를 다단 축류 터빈 전산해석 결과 및 실험결과와 비교하여 신뢰성을 확인하였다.

• 대한원격탐사학회지
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• 제35권1호
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• pp.1-13
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• 2019

The advent of a fourth industrial revolution, built on advances in digital technology, has coincided with studies using various unmanned aerial vehicles (UAVs) being performed worldwide. However, the accuracy of different sensors and their suitability for particular research studies are factors that need to be carefully evaluated. In this study, we evaluated UAV photogrammetry using smart technology. To assess the performance of digital photogrammetry, the accuracy of common procedures for generating orthomosaic images and digital surface models (DSMs) using terrestrial laser scanning (TLS) techniques was measured. Two different type of non-surveying camera(Smartphone camera, fisheye camera) were attached to UAV platform. For fisheye camera, lens distortion was corrected by considering characteristics of lens. Accuracy of orthoimage and DSM generated were comparatively analyzed using aerial and TLS data. Accuracy comparison analysis proceeded as follows. First, we used Ortho mosaic image to compare the check point with a certain area. In addition, vertical errors of camera DSM were compared and analyzed based on TLS. In this study, we propose and evaluate the feasibility of UAV photogrammetry which can acquire 3 - D spatial information at low cost in a construction site.

• 수완나부미
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• 제13권2호
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• pp.167-186
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• 2021

The Grand Stupa is mentioned in historical text as 'Rajakudakan', which means a royal building with a multitiered superstructure. This Grand Stupa is the principal construction of Wat Chedi Luang, and marks the center of the Chiang Mai City Plan. This study argues that the Grand Stupa was built in 1391 during Phaya Saen Mueang Ma's reign, possibly inspired by the construction of Ku Phaya in Bagan. Thereafter, in 1545, the Grand Stupa's superstructure collapsed after the great earthquake, resulted in the irreparable damage since then. Therefore, a survey using a 3D laser scanner is conducted to collect the most precise data on the current condition of the Grand Stupa, yielding an assumption of its reconstruction. Other simultaneous stupas or those that show a close architectural relationship (e.g. stupas in Wat Chiang Man and Wat Lok Moli and the stupa of King Tilokaraj in Wat Chet Yot in Chiang Mai) are also employed as research frameworks for the reconstruction. As a result, the architectural research on the Grands Stupa, compared with simultaneous stupas, yields a fruitful argument that the pre-collapse superstructure form of the Grand Stupa marks the most architectural similarity to the stupa of Wat Chiang Man.

• Human Ecology Research
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• 제52권5호
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• pp.509-518
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• 2014

This study strives to analyze the characteristics of and changes in breast shapes of women in their 30s, whose bodies start to age and whose breasts experience changes due to internal and external factors such as pregnancy, childbearing, and breast-feeding. The analysis of the indirect breast measurements for each age group (early, mid, and late 30s) demonstrates that the volume of the breasts increases proportionally with age, the breasts lose their firmness, and the nipples start to point downwards rather than to the sides. The breast shapes experience more significant changes vertically than horizontally as the breasts start to sag downwards. The composition factors of the breasts have been classified into five factors: the level of volume in the breasts and the surrounding area, the degree of sagging in the breasts, the position and vertical width of the breasts, the volume of the breasts, and the degree of width between the breasts. The breasts have been categorized into three different shapes. Breast Shape I (32.56%) appeared most frequently among women in their mid 30s, and this shape falls into the category of Sagging I, which is one of the six breast types that have been classified by the Japanese Wacoal Research Center, in addition to Korean size 80A. Breast Shape II (38.76%) appeared most frequently among women in their mid 30s, and this shape has been categorized as flat with its size being 70A. Breast Shape III (28.68%) appeared most frequently among women in their early 30s with a conical shape and size 75A.