• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.187-193
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• 2004

For a power source of usual electronic devices such as PDA, smart phone, UPS and electric vehicle, the battery made of serially connected multiple cells is generally used. In this case, if there are some unbalanced among cell voltages, the total lifetime and the total capacity of the battery are limited to a lower value. To maintain a balanced condition in cells, an effective method of regulating the cell voltage in indispensable. In this paper, we propose the design of a balancing circuit for electronic appliances. The balancing system was controlled by a micro-controller which enables to implement the balancing action during charging period. Proposed method has been verified by the experiment using the charger and recorder. The experimental results show that the individual battery equalization can improve battery capacity and battery lifetime and performance through an extended operational time.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.688-696
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• 2001

Vaporizing characteristics of two GDI injectors with different spray angles were investigated using exciplex fluorescence method. Injector I has narrower spray angle, while injector II has wider one. The exciplex system of fluorobenzene and DEMA in a non-fluorescing base fuel of hexane was employed. In quantifying concentration of fuel vapor, quenching of concentration and temperature was corrected. Droplet size and velocity were also measured by PDPA under non-vaporizing condition. From obtaining the images of liquid and vapor phases, vaporizing GDI sprays could be divided as two regions: cone and mixing regions. For injector I, vortex region was not developed. High concentration of fuel vapor due to vaporization of many fine droplets was distributed near the spray axis. For injector II, droplets with the diameter of about 10 $\mu$m were distributed in the vortex region. The vortex region had high concentration of fuel vapor due to vaporization of these droplets. Particularly, higher and lower concentrations of fuel vapor were balanced at 2ms after the start of injection for injector II.

• Journal of Families and Better Life
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• v.33 no.2
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• pp.21-33
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• 2015

This study was carried out to explore the actual condition of family-friendly education of corporations and organizations supporting them for the purpose of activating the family-friendly certification system. The researches on the family-friendly education of corporations or related organizations have not become an object of attention, although the policies of family-friendly corporations have been the major concern of researchers who have conducted studies on the balancing between work and family. For the first time, this study investigated the family-friendly education programs of corporations and organizations supporting them. In addition to this work, interviews with laborers were performed to learn the actual participation in the education. The results showed that even corporations selected as excellent corporations by the government scarcely provided family-friendly educations and few laborers participated in them. The most educations provided by corporations were for the improvement of work ability or job training. Education for family concentrated only on the role of the father. The focus of educations supporting corporations was biased to the view of corporation or family, not balanced between the two. So it was suggested that researchers should pay attention to developing diverse education programs encompassing the whole stages of life cycle and the balancing between corporation and family.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.121-126
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• 2008

This paper analyzes the losses of a Steinmetz connection three-phase induction motor which is supplied by a single-phase source. The T-type equivalent circuit which is taken no-load losses into account is used to determine phase converter capacitive reactances at starting and rated speed by using the condition of the minimum voltage unbalance. The starting and the operating capacitor are replaced at the slip of the same voltage unbalance factor points which are depicted using two capacitive reactances. The operation characteristics are investigated by comparing with those of three-phase balanced operation to find the feasibility of single-phase operation. To analyze the losses of this motor, the output power decrease factor(OPDF), the loss ratio(LR), the no load loss ratio(NLLR), the copper loss ratio(CLR), the stator copper loss ratio(SCLR), and the rotor copper loss ratio(RCLR) are defined and simulated in the whole slip range. The simulated results show that OPDF is maintained almost uniformly, LR is low at low speed and high at high speed, CLR is higher !ban NLLR, but CLR varies concavely and NLLR varies convexly at high speed, SCLR is low at low speed and high at high speed, but SCLR varies convexly at high speed, and RCLR is nearly opposite to SCLR.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.221-228
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• 1998

In order to look into the comparative flow characteristics between a circular contraction duct and a circular expansion duct the both centerline turbulent structures have been investigated by the hot wire anemometry. Both of the contraction and the expansion have Morel type contours. Means, turbulences, and triple moments have been measured for the turbulent kinetic energy budgets along their centerlines. It is resulted that mean velocities of both have much deviated from theoretical values calculated by one-dimensional continuity considerations, and that for the same upstream condition, the expansion maintains the isotropy in general while the contraction maintains a severe anisotropy through the whole duct. The mean transport of the TKE along the expansion is willing to balance mostly with the dissipation in the TKE budgets while that along the contraction is balanced with the production in the turbulent kinetic energy equation.

• Steel and Composite Structures
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• v.18 no.3
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• pp.565-582
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• 2015

This paper is concerned with the dynamic analysis of simply-supported steel-concrete composite beams under moving loads. Considering the interface slip between steel girder and concrete slab, the governing motion equations are derived from the direct balanced method. By variable separation approach, the analytical solution of natural frequencies and mode shapes are obtained, as well as the orthogonal conditions. Then the dynamic responses of the composite beam under moving loads are analyzed, and compared with the experimental results. The analysis results show that the governing motion equations become more complicated when interface slip is taken into account, and the dynamic behaviors are significantly influenced by the shear connection stiffness. In the dynamic calculation of composite beams, the global stiffness should not be reduced as the same factor to all orders, but as different ones according to the dynamic stiffness reduction factor (DSRF), to which should be paid more attention in calculation, design and experiment, or else great deviation is inevitable.

• International Journal of Railway
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• v.3 no.2
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• pp.54-59
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• 2010

In order to develop the deep-underground GTX (Great Train eXpress) in domestic, the running performance analysis of the propulsion system by a variety of route condition must be carried out before studying the specification and the development of the high-speed propulsion system with inverter and traction motor. Then it is necessary to study the running resistance properties of the high-speed traction system for the variety of tunnel type and vehicle organization method at first. In addition, the properties of the power requirement of the traction motors needed to maintain the balanced speed of the high-speed traction system are next studied. We need to study properties of the emergency braking distance caused by the highest operation speed of the high-speed traction system and present the fundamental design technologies to develop the high-speed traction system for the deep-underground GTX. Finally, the paper analyzes the applicability of the conventional Korean Tilting Train eXpress (TTX) propulsion system on the high-speed propulsion system for the deep-underground GTX.

• Journal of Families and Better Life
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• v.23 no.3 s.75
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• pp.1-16
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• 2005

This study explored the elements, types, and determining factors of successful aging for the Korean elderly. In order to examine the expectations of the Korean elderly, a sample of 377 elderly aged 65 and over living in Seoul and Kyunggi areas was selected and interviewed. The elements of successful aging that the Korean elderly pointed out in the interviews were: 'peaceful and comfortable life', 'self-maintenance,' 'secure social support,' and 'ostentation.' The expected elements of successful aging were further classified into three types of successful aging: 'idealized expectation.' 'self-centered expectation,' 'balanced self-other expectation.' The elderly groups sorted by the types exhibited significant differences in terms of demographic characteristics, self-evaluated economic status, and self-evaluated health status. The variables that affected the expectations were age, level of education, marital status, gender, and self-evaluated health condition. However, further analysis revealed that the factors that affected the expectation for successful aging were different for male and female elderly. The results suggest that the successful aging of Korean elderly should be understood in the context of Korean society and culture. The results could be used to better understand varied and unique life of Korean elderly, as well as in establishing a basis of intervention that meets the specific demands of the Korean elderly.

• Korean Journal of Community Nutrition
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• v.8 no.2
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• pp.129-137
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• 2003

This study was to investigate obesity and food habit of adolescents in Yosu, Chonnam area. It was surveyed using questionnaires with 551 adolescents consisted of 280 boys and 271 girls. The questionnaire included general charac-teristics, obesity index, eating behavior and snack intake pattern. The results were as follows. The proportion of obese subjects was 10% by Rohrer index but the rate of obesity by body mass index was 3.3%. The self perception of body shape were optimal (47.9%), fat (29.8%), slightly lean (14.5%), obese (4.7%) and lean (3.1%). Generally, the propor-tion of girls responded them as “fat” was greater than boys. The greater percentage of boys responded them as “lean” than girls. The subjects don't take breakfast regularly were 50.8% and the main reason for skipping breakfast was the lack of time (55.2%). The main type of breakfast was cooked rice (78.9%). The most favorite snacks hun out to be cookies (36.5%) and 45.7% of subjects take snacks during the rest. The reason for taking snacks was “feeling hungry” (52.6％) and the taste was the most important factor of snack choice. The results of this study showed that the most of subjects were not in a serious obesity condition, and their eating habits were generally satisfactory. Also, this study has found that it is necessary to educate the students the importance of regular intake of a balanced meal. (Korean J Community Nutrition 8(2) : 129∼137, 2003)

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.353-360
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• 2006

The nominal structural stress calculation method proposed by Radaj has included some problems as follows: (a) How the value of the diameter D is decided in the method; (b) It is not possible to estimate nominal structural stress of the spot welded joints with the balanced sheet in-plane load that no general loads are obtained by FE shell analysis. In this paper, the new method for calculating nominal structural stress was proposed to solve above-mentioned problems. The proposed method calculates the nominal structural stress through the circular plate theory in theory of elasticity. This theoretical analysis uses not only general loads but also nodal displacements around spot welding provided by FE shell analysis as boundary condition. Fatigue test data of various spot-welded joints could be arranged in a narrow bandwidth on S-N chart using the nominal structural stresses calculated by proposed method. The fatigue life prediction method using the proposed method for calculating nominal structural stress is useful for the prior evaluation technique that can predict the fatigue life of spot welding by CAE.