• Journal of Nutrition and Health
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• 제32권1호
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• pp.40-49
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• 1999

This study was conducted with 20 female gymnasts and 23 age-matched controls to examine pattern, weight control behavior and nutritional status. Most gymnasts(95.0%) reported that they used weight-control methods, while relatively few age-matched controls employed these methods. These methods included sauna(95.0%), food restriction(90.0%), excess exercise (70.0%), laxative abuse(10%) and use of diet pills(10%). Gymnasts had significantly (p<0.05) lower scores for statements related to 'sneaking food', 'vomiting after overeating', showing more negative eating behavior than age-matched controls. Energy intake of gymnasts was 968.9$\pm$421.4kcal while energy expenditure was 2,091$\pm$361kcal, showing negative evergy balance(-1,1225$\pm$534.6kcal). Female gymnasts consumed less than 70% of the RDA for protein, calcium, iron, vitamin A, thiamin, riboflavin and niacin, which reflects their low energy intake. The average intakes of calcium, iron, vitamin A, thiamin, riboflavin and niacin did not meet the recommended dietary allowances for their age groups. Adolescent athletes who train vigorously and consume a low-energy diet may be exposed to an increase in potential health risks. Therefore, individuals who advise athletic adolescents regarding training and dietary habits need to emphasize the importance of consuming an appropriate energy intake to support performance as well as growth and development. The sports nutritionist is in a position to convey such information to coaches, physicians, parents and to the athletes themselves.

• 연구논문집
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• 통권26호
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• pp.5-14
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• 1996

Test results of electromagnetic suspension (EMS) type urban transit maglev system are reported. Electromagnetic levitation system is a transportation system taking advantage of the attraction of normal conducting electromagnets to support and guide the train in combination with the linear induction traction motors. Urban Transit Maglev (UTM) Which is being developed by the maglev team in KIMM and the Hyundai Precision Company since 1995 consists of three bogies. In the first year, two types of Bogies are developed. Bogie I uses an analog controller for levitation and guidance control and is driven by two linear induction motors (LIM) mounted on the right and left side of module. Bogie II uses a digital controller and is driven by one LIM mounted along the center line of the bogie. Test results reported in this paper are those obtained with Bogie II with a digital controller. Also included in this paper is a brief explanation of the electromagnetic suspension levitation system which is being developed by the maglev team in KIMM.

• 전력전자학회논문지
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• 제9권2호
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• pp.158-162
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• 2004

자기부유기는 전자력을 이용해서 자성재료를 공중에 떠있게 할 수 있는 장치로 고속회전기에 사용되는 자기 베어링과 자기 부상 열차의 부상원리 등에 응용될 수 있다. 하지만 자기 부유기는 근본적으로 비선형이며 불안정한 시스템으로서 제어에는 많은 어려움이 따른다. 본 논문에서는 비선형 시스템인 자기부유기를 국부적으로 선형화해서 모델링하고, 가변 위치 제어를 수행할 수 있도록 비례미분 위치제어기를 설계하였다. 또한 PWM 컨버터와 DSP기반 제어보드를 이용한 자기 부유기를 제작하고, 시뮬레이션과 실험을 통하여 위치제어 응답성능을 검증하였다.

• 한국통신학회논문지
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• 제38C권5호
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• pp.471-478
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• 2013

본 논문은 국내 철도 건널목의 현황 조사와 현재 운영되고 있는 안전설비의 문제점 분석을 통해 이를 해결할 수 있는 대안으로 레이저레이더기반의 지장물 검지장치를 설계 및 구현하였다. 철도 안전사고의 큰 비중을 차지하는 철도 건널목에서의 효과적인 지장물 검지를 통해 철도교통의 안전성 및 신뢰성 향상을 목표로 하며, 기존 안전 설비의 한계와 노후화로 인한 문제점을 극복하는 시스템을 제안한다. 레이저레이더 스캐너를 활용한 철도 건널목 지장물 검지장치를 설계하였고 시제품 시험 및 성능평가를 통해 이를 입증하였다.

• 한국전기전자재료학회논문지
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• 제18권1호
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• pp.1-5
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• 2005

A new model of plasma etch process was constructed by using a radial basis function network (RBFN). This technique was applied to an etching of silicon carbide films in a NF$_3$ inductively coupled plasma. Experimental data to train RBFN were systematically collected by means of a 2$^4$ full factorial experiment. Appropriateness of prediction models was tested with test data consisted of 16 experiments not pertaining to the training data. Prediction performance was optimized with variations in three training factors, the number of pattern units, width of radial basis function, and initial weight distribution between the pattern and output layers. The etch responses to model were an etch rate and a surface roughness measured by atomic force microscopy. Optimized models had the root mean-squared errors of 26.1 nm/min and 0.103 nm for the etch rate and surface roughness, respectively. Compared to statistical regression models, RBFN models demonstrated an improvement of more than 20 % and 50 % for the etch rate and surface roughness, respectively. It is therefore expected that RBFN can be effectively used to construct prediction models of plasma processes.

• 소성∙가공
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• 제29권5호
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• pp.282-289
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• 2020

Flexible roll forming is an advanced sheet-metal-forming process that allows the production of parts with various cross-sections. During the flexible process, material is subjected to three-dimensional deformation such as transverse bending, inhomogeneous elongations, or contraction. Because of the effects of process variables on the quality of the roll-formed products, the approaches used to investigate the roll-forming process have been largely dependent on experience and trial- and-error methods. Web-warping is one of the major shape defects encountered in flexible roll forming. In this study, an SVR model was developed to predict the web-warping during the flexible roll forming process. In the development of the SVR model, three process parameters, namely the forming-roll speed condition, leveling-roll height, and bend angle were considered as the model inputs, and the web-warping height was used as the response variable for three blank shapes; rectangular, concave, and convex shape. MATLAB software was used to train the SVR model and optimize three hyperparameters (λ, ε, and γ). To evaluate the SVR model performance, the statistical analysis was carried out based on the three indicators: the root-mean-square error, mean absolute error, and relative root-mean-square error.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.526-531
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• 2011

A dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train. Meanwhile, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it seems important to provide an optimal design scheme incorporating sound packages such as dash isolation pad and carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. The system taken into account in this paper is a dash panel component of a sedan, which includes A pillar, front side member, dash panel and the corresponding sound packages. Design variables such as panel thickness and sound package layers are investigated how they are related for the better radiation performance (i.e. structure-borne) and sound transmission loss (i.e. air borne).

• 한국소음진동공학회논문집
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• 제21권2호
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• pp.178-185
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• 2011

Optical image stabilization is a device to compensate the camera movement in the exposure time. The compensation is implemented by movable lens or image sensor that adjusts the optical path to the camera movement. Generally, the camera is moved by a handshake, thus the handshake is considered as an external disturbance. However, there are many other vibrations such as car and train vibration. In this paper, the optical image stabilization system in high frequency region is presented. Notch filter and lead compensator are designed and applied to improve the stability without changing the actuator. To verify the performance of the optical image stabilization system in high frequency region, the experiment equipment with moving object is established. It is confirmed that the opticalimage stabilization system does not diverge at the resonance frequency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.1086-1092
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• 2002

Computer simulation is essential to design the suspension elements of railway vehicle. By computer simulation, engineers can assess the feasibility of a given design factors and change them to get a better design. But if one wishes to perform complex analysis on the simulation, such as railway vehicle dynamic, the computational time can become overwhelming. Therefore, many researchers have used a mega model that has a regression model made by sampling data through simulation. In this paper, the neural network is used a mega model that have twenty-nine design variables and forty-six responses. After this mega model is constructed, multi-objective optimal solutions are achieved by using the differential evolution. This paper shows that this optimization method using the neural network and the differential evolution is a very efficient tool to solve the complex optimization problem.

• 한국정밀공학회지
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• 제28권5호
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• pp.572-577
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• 2011

Curve squealing of inter-city railway vehicle is a noise with high acoustic pressure and rather narrow frequency spectra. This noise turns out to be very annoying for the people living in the neighborhood of locations and the passenger in railway vehicle where this phenomenon occurs. Squealing is caused by a self-exited stick-slip oscillation in the wheel-rail contact. Curve squeal noise of railway vehicles that passed by a factor of the speed limit, so to overcome in order to improve running performance is one of the largest technology. In the present paper, characteristic of squeal noise behavior at the Hanvit-200 tilting train test-site. Curve squealing of railway wheels/rail contact occurs in R400~ R800 curves with a frequency range of about 4~11 kHz. If the curve is less than the radius of wheel frail contact due to |left-right| noise level difference (dBA) shows a significant effect of squeal noise were more likely.