• Journal of Power Electronics
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• 제15권6호
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• pp.1609-1618
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• 2015

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

• 동아시아식생활학회지
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• 제15권3호
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• pp.271-282
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• 2005

This study analyzed the physical indices, food habits and nutrient intakes of patients with hypertension, to provide better research data for the prevention and the cure for disease as well as basic data for nutrition education. The subjects were 44 patients who visited the general hospital, located in Daegu, to receive hypertension treatment The lifestyle, food habit, nutrient intakes, anthropometric measurements, body fat and blood pressure were measured as main indices. By the BMI, $72.8\%$ of the patients were over weight or obesity $(>23\;kg/m^2)$. In the male group, the WHR tended to increase according to the BMI (p<0.05). In the female group, the body fat tended to increase according to the BMI (p<0.05). The group with more monthly income showed lower systolic blood pressure than the group with smaller monthly income (p<0.05). The scores about food habits concerning balanced diet and preference for salt were low, which implied that food habits of subjects were not desirable. The intakes of riboflavin and calcium didn't meet the RDA requirements. Especially, the lack of calcium was more ap~nt in the female patients than the male ones. Despite this, they had more than enough protein, vitamin C, and iron. The physical indices according to blood pressure revealed that the group of higher blood pressure showed greater WHR (p<0.001). The male group with higher systolic blood pressure showed greater BMI than one with lower systolic blood pressure (p<0.05). As for nutrient intakes according to blood pressure, the group with higher blood pressure had more sodium and iron than one with lower blood pressure (p<0.05). The patients with hypertension tended to be more overweight or obese, preferred salty foods, and were in an unbalanced state of nutrient intakes. Thus more systematic and ongoing measures should be pursued to take care of patients with hypertension.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2000년도 암반공학문제의 수치해석(Numerical Analysis in Rock Engineering Problems)
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• pp.195-200
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• 2000

폐갱도를 이용하여 관광공원을 조성할 목적으로 지하에 건설될 예정인 대형 지하광장의 안정성을 분석하기 위하여 FLAC3D를 이용한 3차원 수치해석을 수행하였다. 모델링은 두 단계로 나누어 실시되었다. 첫 단계는 지하광장 자체의 안정성 분석이며, 두 번째 단계는 인근의 채굴적이 미치는 영향분석이다. 첫 번째 단계에서는 모델의 불평형력 수렴 여부, 광장 주변의 소성 또는 인장파괴 영역의 발생상황 그리고 변위 양상으로써 광장의 안정성을 판단하였다. 두 번째 단계에서는 채굴적의 존재 유무에 따른 광장 주변의 응력상태 변화를 분석하였다. 해석결과 대형 지하광장은 역학적으로 아무런 문제가 없으며 채굴적으로 인한 영향도 받지 않는 것으로 나타났다.

• 터널과지하공간
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• 제10권3호
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• pp.441-446
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• 2000

폐갱도를 이용하여 관광공원을 조성할 목적으로 지하에 건설될 예정인 대형 지하광장의 안정성을 분석하기 위하여 FLAC3D를 이용한 3차원 수치해석을 수행하였다. 모델링은 두 단계로 나누어 실시되었다. 첫 단계는 지하광장 자체의 안정성 분석이며, 두 번째 단계는 인근의 채굴적이 미치는 영향분석이다. 첫 번째 단계에서는 모델의 불평형력 수렴 여부, 광장 주변의 소성 또는 인장파괴 영역의 발생상황 그리고 변위 양상으로써 광장의 안정성을 판단하였다. 두 번째 단계에서는 채굴적의 존재 유무에 따른 광장 주변의 응력상태 변화를 분석하였다. 해석결과 대형 지하광장은 역학적으로 아무런 문제가 없으며 채굴적으로 인한 영향도 받지 않는 것으로 나타났다.

• 한국인터넷방송통신학회논문지
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• 제17권5호
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• pp.199-208
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• 2017

리튬 폴리머 배터리는 높은 안전성, 빠른 충전 및 긴 라이프 사이클 등으로 인해 에너지 저장치(ESS: Energy Storage System), 전기자동차(EVs: Electric Vehicles)등에 채택이 되어 사용되고 있으며, 그리고 현재는 농업용 드론에서 까지 사용이 되고 있다. 그러나 리튬 폴리머 배터리는 과충 방전에는 리튬-이온 배터리 내의 격차구조가 파괴되어 배터리 수명이 줄어들게 되며, 과충 방전을 방지하기 위해 불균등한 셀 전압을 균등 제어 할 수 있는 셀 밸런싱 시스템이 필수적이다. 본 논문은 각 셀의 충 방전할때의 전압차이를 검출하여 불균형된 셀을 확인하여 비선형 시스템에 적합한 퍼지 제어기를 개발하여 적용한 셀별 밸런싱 알고리즘을 제안한다. 본 논문은 농업용 드론의 배터리팩의 셀 밸런싱을 퍼지제어를 하여 셀 간 균등 제어를 위해 설계하였으며, 최종 결과로 셀 간 밸런싱이 잘 되는지 확인하고 자 셀이 2개 있을 때와 6개 그리고 최종적으로 12개의 각 셀 밸런싱이 되는지를 확인하였다. 이는 다른 제품에도 사용할 수 있는지를 실험하고자 하였으며, 확인결과 사용된 셀의 개수와는 관계없이 셀별 밸런싱이 잘 되고 있음을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제33권4호
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• pp.525-530
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• 2020

Objective: The purpose of this study was i) to identify the characteristics of carcass traits in Chikso by gender, region, age at slaughter, and coat color using the carcass data collected from the nationwide pedigree information and coat color investigation, and ii) to estimate genetic parameters for breed improvement. Methods: A linear model was used to analyze the environmental effects on the carcass traits and to estimate genetic parameters. Analysis of variance was performed using TYPE III sum of squares for the unbalanced data provided by the general linear model procedure. Variance components for genetic parameters was estimated using REMLF90 of the BLUPF90 family programs. Results: Phenotypic performance of carcass weight (CW), eye muscle area (EMA), and backfat thickness (BF) in Chikso were lower than those of Hanwoo. This is a natural outcome because Hanwoo have undergone significant efforts for improvement at the national level, a phenomenon not observed in Chikso. Another factor influencing the above outcome was the smaller population size of Chikso compared to that of Hanwoo's. The heritabilities of CW, EMA, BF, and marbling score in Chikso were estimated as 0.50, 0.37, 0.35, and 0.53, respectively, which were was higher than those of Hanwoo. Conclusion: Based on the genetic parameters that were estimated in this study, it is expected that the carcass traits will improve when the livestock research institutes at each province conduct small-scale performance tests and the semen is provided to farmers after selecting proven bulls using the state-of-art selection technique such as genomic selection.

• Journal of Power Electronics
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• 제16권5호
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• pp.1869-1883
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• 2016

In recent years, some converter structures and analyzing methods for the voltage regulation of stand-alone self-excited induction generators (SEIGs) have been introduced. However, all of them are concerned with the three-phase voltage control of three-phase SEIGs or the single-phase voltage control of single-phase SEIGs for the operation of these machines under balanced load conditions. In this paper, each phase voltage is controlled separately through separated converters, which consist of a full-bridge diode rectifier and one-IGBT. For this purpose, the principle of the electronic load controllers supported by fuzzy logic is employed in the two-different proposed converter structures. While changing single phase consumer loads that are independent from each other, the output voltages of the generator are controlled independently by three-number of separated electronic load controllers (SELCs) in two different mode operations. The aim is to obtain a rated power from the SEIG via the switching of the dump loads to be the complement of consumer load variations. The transient and steady state behaviors of the whole system are investigated by simulation studies from the point of getting the design parameters, and experiments are carried out for validation of the results. The results illustrate that the proposed SELC system is capable of coping with independent consumer load variations to keep output voltage at a desired value for each phase. It is also available for unbalanced consumer load conditions. In addition, it is concluded that the proposed converter without a filter capacitor has less harmonics on the currents.

• 한국의류산업학회지
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• 제14권1호
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• pp.136-143
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• 2012

The purpose of this study was to investigate the influence of physical functions of elderly people on their clothing behavior and to provide basic information about manufacturing comfortable apparels for the elderly. A total of 219 people, with ages between 60s and 70s, participated in the survey and in the experiment to correlate their tendency of wearing clothes with the state of their physical functions. About 78.5% of the elderly showed eyesight deterioration in the subjective evaluation. Elders in their 60s raised their arms higher up in overhead reach, and showed shorter distance between middle fingertips in behind back stretch and in back scratch than elders in their 70s. Also, the former stretched farther to the floor in standing trunk flexion, and maintained more steady in one leg stand and in tandem stance than the latter. The narrower the movement range of the upper limb joints was, the more the elderly preferred upper garments with full front opening to those with half or no opening. The more inflexible the upper limbs and waist and the more unbalanced the body was, the more likely the elderly put on pants while sitting on the floor. The time taken to button up the shirt and to put on and take off pants showed a positive correlation with the overhead reach, the behind back stretch, the back scratch and the standing trunk flexion, whereas the former showed a negative correlation with the one leg stand and the tandem stance.

• 동아시아식생활학회지
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• 제9권3호
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• pp.315-324
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• 1999

This study was carried out to evaluate high-school students' nutrient intakes according to the status of body mass index, and to analyze the Physical health status. The volunteers were 560 high school students in 8 provinces, but 511 students were analyzed. It was used questionnaire method as an instrument tool. The questions were composed with socio-demographic characteristics, physical health condition by CMI. and the evaluation of food consumption by 24 hours recall method. Anthrophometric measurement of height and weight was used the data of health chart of each school-class. The family situation of the subjects was mostly nuclear family(73%), agricultural work(53%), and normal living situation(75%). The students of the BMI range of 18-23 were 71%. but those of the overweight(over 23) were 15%. The individual characteristics were different in BMI. Female and third grade students were more of BMI scores. The overall nutrient intakes of students were low compared with Korean RDA of adolescent. especially iron. calcium. vitamin A, and riboflavin. The mean adequacy ratio(MAR) of nutrient intakes was 0.45$\pm$0.23 only. The energy nutrients, ash, and vitamin A intakes were significantly different according to the different BMI groups. But the other mineral and vitamin intakes were not different according to BMI. By the correlation of individual characters with BMI, height was negatively and weight and school grade were positively correlated, but sleeping time and study accomplishment were not correlated. By the correlation of nutrient intakes with BMI, there were negative correlation with the intakes of energy, carbohydrates, potassium, and thiamin. According to this results, We concluded that Korean high-school students living in rural were lower intake of nutrients(iron, vitamin A, and riboflavin) and unbalanced nutrient intakes(MAR of 0.45$\pm$0.23). The state of lower intakes of energy nutrients and vitamin A intakes in higher BMI group mean the students spend their effort to reduce BMI for avoiding obesity. But they need to balanced diet. and good nutrient intakes. These situations would be necessary for students to ameliorate quality of living in rural.

• Korean Journal of Acupuncture
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• 제29권1호
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• pp.71-81
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• 2012

Objectives : The purpose of this paper was to suggest new diagnostic method that was to supersede the estimation of electrical properties at acupoints. Thus, we developed the multi- frequencies bioelectrical impedance measurement system so as to analyze the state of bio-ions in body fluid as body compositions, not skin impedance at acupoint. Methods : At low frequency, the current does not penetrate the cell membrane and at high frequency, the current passes through both intracellular and extracellular fluid because of the decreas of cell membrane impedance. To confirm the reflection of composition in extracellular fluid or intracellular fluid of segment such as acupoint, the system was developed to detect the acupoint potential between adjacent two points in the area of LU3, LU4 and LU9 using 5,50 and 200KHz. Results : The detected acupoint potential has been decreased according to elevation of frequency. As a result of correlation of left/right identical acupoint, we observed a high correlation of three types of acupoint potential at multi-frequencies. Moreover, we observed the low correlation at 5KHz, and that was a significant factor to be considered as unbalanced relationship of identical acupoints. Conclusions : On the basis of meridian theoretical point of view, we may infer the acupoint's physiological composition using the multi-frequencies bioelectrical impedance measurement system.