• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2052-2060
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• 2017

The SOLAS ship should carry at least 83 different types of equipment based on the SFI group codes and each of which consists of several to dozens of components. During ship operation, it is necessary to ensure the normal operation of such equipment, and remote maintenance is highly demanded for immediate repair in the event of a equipment fault. This study proposes to find suitable classification system and to derive database structure for remote maintenance of navigation and communication equipment. As a result of this study, the classification system of equipment should be layered into equipment type, model, and component, and main table in the database consists of FMEA, service history, case data through Q&A, Preventive Maintenance. A database was constructed for 140 navigation and communication equipment models and 750 components. In order to evaluate the practical effects, service engineer evaluated the usefulness using the cloud app.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.54-59
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• 2005

Nonlinear aeroelastic analyses of a missile control fin are performed considering backlash and dynamic stiffness of actuator. Doublet-Hybrid method is used for the calculation of subsonic unsteady aerodynamic forces, and aerodynamic forces are approximated by the minimum-state approximation. For nonlinear flutter analysis backlash is represented by a free-play and is linearized by using the describing function method. Also, dynamic stiffness is function of frequency and is calculated by solving equation of motion for actuator. The linear and nonlinear flutter analyses show that the aeroelastic characteristics are significantly dependent on the backlash and dynamic stiffness. From the nonlinear flutter analysis, various types of limit cycle oscillations are observed in a range of air speeds below the linear divergent flutter boundary. The nonlinear flutter characteristics and the nonlinear aeroelastic responses are also investigated in the time domain.

• Journal of IKEEE
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• v.24 no.1
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• pp.154-160
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• 2020

This paper presents a grid current control algorithm for a grid connected inverter (GCI) system in a stationary reference frame. When a Proportional Integral (PI) controller at a stationary reference frame is used in a GCI system, steady state error and phase lags are presented because AC signals are controlled at a stationary reference frame. In this paper, a feedforward controller is applied to the PI controller to compensate the steady state error and phase lags by improving command tracking performance. In addition, disturbance rejection control is applied to the PI controller to protect the GCI system by eliminating disturbance, grid voltage in a GCI system, when a grid fault such as line-to-line fault, happens. The proposed GCI current control algorithm is analyzed in a frequency domain and a simulation model of the proposed GCI current control system is developed for verification of the performance.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.91-103
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• 2004

A series of shaking table model tests were performed to verify the validity of similitude law, which is suggested by lai (1989) to simulate the dynamic behavior of soil-fluid-structure system for is shaking table tests. In the tests, the similitude law suggested by lai was applied to determine the length and the time scaling factors. Also, the steady state concept was used in determining the density of model backfill soil, which is a key factor in simulating the development of excess pore pressure during shaking. The similitude law was verified by checking whether three different sizes of quay walls show the identical behavior or not. The similar responses of acceleration, excess pore pressure and horizontal displacement of walls were obtained far the small and large models. However, the medium model showed larger responses than those of the small and large models because of the resonance between the frequency of input acceleration and the natural frequency of the wall system. In addition, the vertical displacement and rotational angle of the walls became larger with the increase of model size.

• Korean journal of food and cookery science
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• v.20 no.5
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• pp.468-479
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• 2004

This study was conducted to investigate factors affecting the bone density of university students in the Seoul area. Data for food habits, and dietary and health-related behavior was obtained by self-administered questionnaires. BQI (bone quality index) of the subjects was measured by a Quantitative Ultrasound (QUS). The results are summarized as follows. The average height, weight, BMI and osteopenia percentage were 175.4cm, 69.3kg, 22.5 and 15.6% for male students, and 161.5cm, 55.9kg, 21.7 and 34.1%, for female students, respectively. The mean BQI of the subjects was 110.25 (range 60.7 ～ 176.8) in male students and 90.64 (range 52.9 ～ 137.5) in female students. Height and weight were significantly related with BQI in the female group but the relationship with BMI was not significantly related with bone density in either group. BQI was positively affected by nutrition supplement in the male student group. One-side eating, diet, and intake of milk and instant food were not significantly related with BQI in males or females. The results of this study revealed that desirable food habits, dietary behavior and health-related lifestyle may have a beneficial effect on bone density. There should be established a practically and systematically organized nutritional education on optimum body weight, good eating habits, weight bearing exercise and intakes of good quality nutrient for higher bone density level.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.6
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• pp.517-523
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• 2002

In this paper, we propose system that apply VIBL method to add speech recognition to LIBL method based on human s studying method to use natural language to steering system of ship, MERCS and winch appliances and use VIBL method to alternate process that linguistic instruction such as officer s steering instruction is achieved via ableman and control steering gear, MERCS and winch appliances. By specific method of study, ableman s suitable steering manufacturing model embodies intelligent steering gear controlling system that embody and language direction base studying method to present proper meaning element and evaluation rule to steering system of ship apply and respond more efficiently on voice instruction of commander using fuzzy inference rule. Also we embody system that recognize voice direction of commander and control MERCS and winch appliances. We embodied steering manufacturing model based on ableman s experience and presented rudder angle for intelligent steering system, compass bearing arrival time, evaluation rule to propose meaning element of stationary state and correct steerman manufacturing model rule using technique to recognize voice instruction of commander and change to text and fuzzy inference. Also we apply VIBL method to speech recognition ship control simulator and confirmed the effectiveness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.368-375
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• 2018

In the present study, aerodynamic load analysis for a floating off-shore wind turbine was conducted to examine the effect of periodic platform motion in the direction of 6-DOF on rotor aerodynamic performance. Blade-element momentum method(BEM) was used for a numerical simulation, the unsteady airload effects due to the flow separation and the shed wake were considered by adopting a dynamic stall model based on the indicial response method. Rotor induced downwash was estimated using the momentum theory, coupled with empirical corrections for the turbulent wake states. The periodic platform motions including the translational motion in the heave, sway and surge directions and the rotational motion in the roll, pitch and yaw directions were considered, and each platform motion was applied as a sinusoidal function. For the numerical simulation, NREL 5MW reference wind turbine was used as the target wind turbine. The results showed that among the translation modes, the surge motion has the largest influence on changing the rotor airloads, while the effect of pitch motion is predominant for the rotations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.149-158
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• 1998

The SAR patterns of biological objects contacted with coaxial waveguide antennal has been investigated, in which the biological object was modeled by a homogeneous and four-layered lossy human body. We derived the finite-difference time-domain(FDTD) algorithm and equation of MUR and generalized perfectly matched layer(GPML) ABCs in cylindrical coordination. The coupling between coaxial waveguide antenna and a biological object was analyzed by use of MUR and GPML ABCs in the FDTD method to obtain the absorbed power patterns in the media. The specific absorption rates (SAR) distribution which was corresponding to the temperature distribution was calculated in each region by use of the steady-state response in the FDTD method. The SAR patterns of the FDTD method using MUR absorbing boundary conditions(ABCs) was compared with those of the FDTD method using GPML ABCs. The comparison exhibits that the penetration depth of the SAR patterns using MUR ABCs is deeper than that of the SAR patterns using GPML ABCs because of loss in free space. However, the spread in the lateral directions of the SAR patterns using GPML ABCs is smaller than of the SAR patterns using MUR ABCs.

• Journal of Nutrition and Health
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• v.41 no.1
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• pp.65-76
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• 2008

This study was performed to identify association between nutritional status and health risks of the elderly. This was a cross-sectional study involving low income elderly women in Gwangju, Korea (${\geq}$65y, n = 92). Socio-demographics, life style characteristics, health conditions, dietary intakes based on 24h-recall method, anthropometric measures, and clinical biochemistry parameters were examined. Anthropometric and clinical parameters included wt, ht, waist, hip, body protein, body fat, abdominal fat, total cholesterol, HDL-cholesterol, triglyceride, total protein, albumin, hemoglobin, hematocrit, fasting blood glucose, ferritin, IL-2, IL-6, TNF-${\alpha}$, CRP, TAS, TBARS, systolic blood pressure, and diastolic blood pressure. The subjects were divided into three groups based on age (65-74y, 75-84y, 85y${\leq}$) and were divided into two groups according to the sum of the Nutrition Screening Initiative (NSI) checklist score (adequate nutritional status, NSI score ${\leq}$3; at risk of malnutrition, NSI score >3). Mean and frequency of variables were estimated. Analysis of Variance, Tukey test, Chi-square test, and Multiple linear regression analyses were performed. Mean BMI and body fat were 25.1 $kg/m^2$ and 40.0%, respectively. However, for over 80% of subjects, the intakes of energy, fiber, thiamin, riboflavin, niacin, folate, Ca, K, and Zn were less than the Korean DRI (EAR or AI). The subjects who had lower NSI score tended to have better health status, eat meals frequently, have less depression, and exercise regularly. The subjects who had higher NSI score tended to have tooth problems, to eat alone most of time, and to be physically unable to cook or feed. Serum IL-6 and TNF-${\alpha}$ were significantly related with nutritional status which suggested higher tendency of inflammatory response. Serum IL-2, TAS, and glucose were significantly correlated with body fat (%) or abdominal fat (%). These results suggest that improving the nutritional status, increasing regular exercise, maintaining normal weight are beneficial to health care of low income elderly women.

• The Korean Journal of Food And Nutrition
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• v.14 no.5
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• pp.430-440
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• 2001

This study was conducted for 474 adult females in Seoul and Kyunggido area to investigate salt intake and related factors influencing salty food. The results of this study are summerized as follows : The mean blood pressure of subjects was 115.8mmHg/77.5mmHg (systolic/diastolic) and the sodium intake by food frequency method was 4447.6 ${\pm}$ 720.4mg. The mean values for height, weight, and BMI of subjects were 160.0${\pm}$4.5cm, 54.5${\pm}$6.8kg and 21.3${\pm}$2.7, respectively. Preferenence of the saltness of food was positively correlated with sodium intake(p<0.05) a]10 frequency of using table salt or soy sauce(p<0.01) . As age increases, food habit was improved. With respect to attitude toward consuming salty food, young women group responded more positively on the items of adventages of consuming salty food and less negatively on the items of disadventages. Age was positively correlated with weight, BMI and blood pressure but negatively correlated with sodium intake and preferenence of the saltness of food.