• International Journal of Aeronautical and Space Sciences
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• 제3권1호
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• pp.9-18
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• 2002

Thermal humidity characteristics were considered theoretically and experimentally. A Simply well-fitted correlation of a saturated vapor pressure-temperature curve of water was introduced based on Antoine equation to make theoretical prediction of relative humidity according to temperature variation. Characteristics of dew point were also examined theoretically and its relation with temperature and humidity was evaluated. The exact mass of water vapor in a specified humidity and temperature condition was estimated to provide useful insight into the idea about how much amount of water corresponds to a specified humidity and temperature condition in a confined system. A simple but well-fitting model of dehumidification process was introduced to anticipate the trend of relative humidity level during GN2(gaseous nitrogen) purge process in a humidity chamber. Well-suitedness of this model was also verified by comparison with experimental data. The overall appearance and specification of two thermal humidity chambers were introduced which were used to perform various thermal humidity tests in order to yield useful data necessary to support validity of theoretical models.

• Clinical and Experimental Pediatrics
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• 제61권1호
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• pp.6-11
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• 2018

Purpose: Mid-upper-arm circumference (MUAC) is considered an alternative screening method for obesity. The aims of this investigation were to examine the ability of MUAC to correctly identify children with elevated body mass index (BMI) and to determine the best MUAC cutoff point for identification of children with high BMI. Methods: Anthropometric measurements (height, weight, and MUAC) from a cross-sectional sample of 7,921 Pakistani children aged 5-14 years were analyzed. Pearson correlation coefficients between MUAC and other anthropometric measurements were calculated. Receiver operating characteristic curve analysis was used to determine the optimal MUAC cutoff point for identifying children with high BMI. Results: Among 7,921 children, the mean (${\pm}$standard deviation) age, BMI, and MUAC were 10.00 (${\pm}2.86years$), 16.16 (${\pm}2.66kg/m^2$), and 17.73 (${\pm}2.59cm$), respectively. The MUAC had a strong positive correlation with BMI. The optimal MUAC cutoff points indicating elevated BMI in boys ranged from 16.76 to 22.73, while the corresponding values in girls ranged from 16.38 to 20.57. Conclusion: MUAC may be used as a simple indicator of overweight/obesity in children, with reasonable accuracy in clinical settings.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.206-214
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• 2013

This paper proposes a new method for monitoring local voltage stability using the saddle node bifurcation set or loadability boundary in two dimensional power parameter space. The method includes three main steps. First step is to determine the critical buses and the second step is building the static voltage stability boundary or the saddle node bifurcation set. Final step is monitoring the voltage stability through the distance from current operating point to the boundary. Critical buses are defined through the right eigenvector by direct method. The boundary of the static voltage stability region is a quadratic curve that can be obtained by the proposed method that is combining a variation of standard direct method and Thevenin equivalent model of electric power system. And finally the distance is computed through the Euclid norm of normal vector of the boundary at the closest saddle node bifurcation point. The advantage of the proposed method is that it gets the advantages of both methods, the accuracy of the direct method and simple of Thevenin Equivalent model. Thus, the proposed method holds some promises in terms of performing the real-time voltage stability monitoring of power system. Test results of New England 39 bus system are presented to show the effectiveness of the proposed method.

• Journal of Astronomy and Space Sciences
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• 제12권1호
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• pp.1-13
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• 1995

We carried out photometric and spectroscopic observatious of the blue compact dwarf galaxy Haro 6 in the Virgo Cluster of Galaxies. The long-slit spectroscopy was employed at three position angles, $\Phi$=$0^{\circ}$, $\Phi$=$30^{\circ}$, and $\Phi$=$120^{\circ}$with CCD camera mounted on the Cassegrain Spectrograph. Based on the mean intrinsic axial ratio < $q_0$ >=0.3, we derived inclination I of the system as $44^{\circ}$using our composite V-band CCD image. Careful analysis on the velocity field of the system shows an asymptotically fiat rotation curve with the maximum rotational velocity $V(r)_{max}$ reaches about 12km/sec. The calculation of the dynamical mass of Haro 6 with a simple mass model is briefly discussed with emphasis on the mass to luminosity ratio. From the IRAS Point Source Cataloque, we derived dust-to-gas ratio which indicates relatively low dust content, thus tempting us to conjecture the youth of the system.

• 대한기계학회논문집A
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• 제41권5호
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• pp.337-343
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• 2017

각종 기공과 같은 결함을 허용하는 다이캐스팅 부품의 강도를 현장 수준에서 평가할 수 있는 이론적 방법을 제안한다. 결함을 갖는 부재의 탄성시험을 통해 강성도를 구하고 이를 결함이 없는 이론적 강성도와 비교함으로써 등가 기공률을 산출한다. 등가 기공률 식은 Eshelby의 함유이론으로부터 유도하였다. 산출된 등가 기공률은 Mori-Tanaka 법을 이용하여 기공결함을 포함하는 재료의 응력-변형률 선도를 그리기 위하여 사용된다. 본 연구에서는 Hollomon 변형경화 모델을 사용하였다. 이 응력-변형률 선도를 이용하면 균일분포의 기공결함을 갖는 다이캐스팅 부재의 강도를 평가할 수 있게 된다. 등가 기공률을 고려한 하나의 이론해로서 직사각형 단면의 다이캐스팅 보에 대한 삼점 굽힘의 탄소성 강도를 소성힌지의 방법으로 유도하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.179-181
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• 2003

Conventional P/PI speed controller of today's servo drives should be manually tuned the controller switching set-point by trial-and-errors, which may translate the drive system down-time and loss of productivity. The adjustable drive performance is heavily dependent on the qualify of the expert knowledge and becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, cceleration/deceleration time, and load disturbances. In this paper, the demands on simple controls/setup are discussed for industry servo drives. Analyzing the frequency content of motor torque command, P/PI control mode switching is automatically peformed with some prior knowledge of the mechanical dynamics. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the whole operating conditions. For comprehensive comparison of traditional P/PI control scheme, extensive test is carried out on actual servo system.

• 한국수자원학회논문집
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• 제34권6호
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• pp.577-586
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• 2001

본 연구에서는 모형의 구조가 상대적으로 간단한 구형펄스모형을 이용하여 I-D-F 곡선을 유도할 수 있는 이론적 방법론을 제시하였다. 강우모형의 구조를 고려하여 유도되는 I-D-F 곡선은 관측 강우의 1차원 및 2타원 통계 특성을 이용하여 추정된 매개변수에 의해 그 형태가 결정되므로 년최대치계열을 이용하여 추정하는 1-D-F 곡선에 비해 비정상적인 강우사상에 상대적으로 덜 민감하게 된다. 본 연구는 서울 및 인천지점에 적용되었으며 이때. 유도 된 I-D-F 곡선은 년최대치계열을 이용하여 유도된 I-D-F 곡선과 비교함으로서 그 적용성을 판단해 보았다. 본 연구의 결과를 요약하면 다음과 같다: (1) 지속기간이 길어짐에 따라 중첩확률은 아주 크게 증가한다. 그러나, 중첩에 따른 강우강도의 증가정도는 지속기간이 증가함에 따라 완만하게 감소하는 추세를 나타내고 있다. (2) 중첩을 고려하는 경우, 특히 지속기간 및 재현기간이 긴 경우에, 강우강도의 증가가 두드러짐을 확인할 수 있었다. 이는 깅 우강도의 계산 시 추정된 중첩확률과 재현기간을 함께 고려함으로 생기는 당연한 결과이다. 아울러, 서울과 인천지점의 비교에서는 서울지점의 경우가 중첩의 효과가 더욱 크게 나타나고 있음을 확인할 수 있었으며, 이는 추정된 중첩확률의 차이, 보다 궁극적으로는 구형펄스모형의 매개변수의 차이로 설명될 수 있다. (3) 본 연구에서 사용한 구형펄스 모형은 강우의 군집특성을 고려하지 못함으로 유도된 I-D-F 곡선도 전체적으로 년최대치를 이용한 I-D-F 곡선에 비해 작은 강우강도를 나타내었었다. 그러나 각 곡선의 전체적인 형태는 유사함을 확인할 수 있었으며 강우의 군집특성을 고려하는 강우모형을 사용할 경우 보다 나은 결과를 유도할 수 있을 것으로 판단된다.

• 한국정밀공학회지
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• 제25권10호
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• pp.48-57
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• 2008

MR Fluid, one of functional fluids, is developed for the application to automobile products. MR CDC damper using MR fluid has following principles. When ar electric current is applied to the solenoid, apparent viscosity of MR fluid passing through the annular gap which acts as magnetic circuits varies directly as the intensity of the current. These devices have a simple structure and excellent lime response characteristics, emerging as the alternatives of the conventional semi-active suspension systems. In this study, a design procedure of the magnetic circuit through the solenoid fore and the flux ring functioning as a magnetic path is investigated so as to optimize the design and performance of MR CDC dampers for the vehicles. In addition, an operating point on the B-H curve, the magnetization according to the variation in the annular gap, the pole piece width and the density of MR fluid are studied to design the optimal piston head within the restrained dimension range.

• 콘크리트학회논문집
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• 제28권1호
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• pp.13-21
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• 2016

기존의 강재 보가 콘크리트에 매립되어 볼트접합 연결되는 기존 하이브리드 접합법의 한계와 단점을 개선하기 위하여 단순한 강접합 절점을 갖는 하이브리드 PC 콘크리트 보 시스템을 개발하였다. 개발된 하이브리드 시스템의 원할한 하중전달을 파악하기 위하여 양단 고정단의 보 실험체 3개를 반복 집중하중 하에서 실험하였다. 주요 변수는 강재 보의 길이로서 지점에서 변곡점까지의 거리의 0.25, 0.5 및 1.0배로 변하였다. 모든 실험체는 동일 주철근 지수를 갖는 철근콘크리트 보에 비해 높은 변위 연성비를 나타냈는데, 보의 반복하중-처짐 관계 및 연성은 강재 보의 길이에 영향을 받지 않았다. 보 길이에 따른 연속 변형률 분포 및 붕괴하중에 기반한 극한하중 예측으로부터 제시된 강접합 절점은 구조적 효율성을 갖는다고 판단된다.

• 패션비즈니스
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• 제1권2호
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• pp.1-19
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• 1997

This thesis is a reflection of Korean aestheticism and how it has evolved and influenced Korean contemporary fashion throughout the last century. Up to the current, there have been five notable trends of fashion that have been influenced from and have reflected the qualities emblematic of various periods in Korean history. They can be characterized as the era of Missionary fashion, Uniform fashion, Salon fashion, Brand Name Fashion, and finally, fashion from the current era of diversification. The specific characteristics of each fashion era have been analized and illustrated in a comprehensive table. Design characteristics of Korean contemporary fashion are as follows : 1. A point of emphasis is given to facial feature, unconstructive design and ample silhouette and A silhouette, two-piece and pants. Korean style wrap skirt, a smooth curve and layered style. 2. Effect of flatness from material; as methods of quilting, reinforced dual stitching(Kaeki), patchwork, embroidery and goldfoil thread extra, it is turned up that texture of cloth stuff and effects of flatness. 3. Simple color combinations give effects in two different directions For instance, white and a variety of vivid colors, a dull color and bright colors, black, blue. 4. Over-design, diffusion of fashion. Based on the design characteristics described above, the essence of Korea's beauty consciousness can be captured and summarized through the following points: 1. Emotionalism and non-characterism: traditional and simple natural beauty and modernized natural beauty. 2. From authoritism to non-authoritism: traditional and formal personal beauty and casual characteristic beauty. 3. Polaris (antithesis) phenomenon: chastic beauty and ostentatious beauty, simplicity and lavishness, conformity of fashion and originality. Although the beauty consciousness of Korean contemporary fashion is changing from traditional passive metaphor to aesthetic expressionism for the new generation, after all the basic foundation or root of the spiritual beauty of idealism is usually recognized by focusing on the face.