• 신재생에너지
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• 제16권2호
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• pp.1-13
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• 2020

The reduction of noise from wind turbines has been studied using various methods. Some examples include controlling wind turbine blades, designing low-noise-emitting wind turbine blades, and using trailing-edge serrations. Among these methods, serration is considered an effective noise reduction method. Various studies have aimed to understand the effects of trailing-edge serration parameters. Most studies, however, have focused on fixed-wing concepts, and few have analyzed noise reduction or developed a prediction method for rotor-type blades. Herein, a noise prediction method, composed of two noise prediction methods for a wind turbine with trailing-edge serrations, is proposed. From the flow information obtained by an in-house program (WINFAS), the noise from non-serrated blades is calculated by turbulent ingestion noise and airfoil self-noise prediction methods. The degree of noise reduction caused by the trailing-edge serrations is predicted in the frequency domain by Lyu's method. The amount of noise reduction is subtracted from the predicted result of the non-serrated blade and the total reduction of the noise from the rotor blades is calculated.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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• pp.166-171
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• 2008

We cannot imagine any more the environment and energy problems are separated from our lives. The various attempts to solve these problems are made all over the world. In this study it was performed to analyze a different heating and cooling load depending on the earth-sheltering method and kind of soils by using TRNSYS 16 as the first step to establish the design guidelines for earth-sheltered architecture, one of the eco-friendly and low energy consuming building types. After performing this simulation, we found the result like this. It is the most lowest load in case of all of walls and roof being earth-sheltered. But considering of the load reduction rate, the effect of earth-sheltering the exterior vertical wall is more efficient for load reduction than the one of earth-sheltering a roof. And we got a lower thermal load in case of a lower heat conductivity of soil. Afterwards we will conduct a further study for boundary condition at earth-sheltered surface and the simulation analysis about the sensitivity variables. The final goal of this study is preparing the design guidelines for earth-sheltered architecture. so we will contribute to building energy saving.

• Asian-Australasian Journal of Animal Sciences
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• 제27권11호
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• pp.1652-1662
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• 2014

The present study investigated the optimum blending condition of protected fat, choline and yeast culture for lowering of rumen temperature. The Box Benken experimental design, a fractional factorial arrangement, and response surface methodology were employed. The optimum blending condition was determined using the rumen simulated in vitro fermentation. An additive formulated on the optimum condition contained 50% of protected fat, 25% of yeast culture, 5% of choline, 7% of organic zinc, 6.5% of cinnamon, and 6.5% of stevioside. The feed additive was supplemented at a rate of 0.1% of diet (orchard grass:concentrate, 3:7) and compared with a control which had no additive. The treatment resulted in lower volatile fatty acid (VFA) concentration and biogas than the control. To investigate the effect of the optimized additive and feed energy levels on rumen and rectal temperatures, four rumen cannulated Hanwoo (Korean native beef breed) steers were in a $4{\times}4$ Latin square design. Energy levels were varied to low and high by altering the ratio of forage to concentrate in diet: low energy (6:4) and high energy (4:6). The additive was added at a rate of 0.1% of the diet. The following parameters were measured; feed intake, rumen and rectal temperatures, ruminal pH and VFA concentration. This study was conducted in an environmentally controlled house with temperature set at $30^{\circ}C$ and relative humidity levels of 70%. Steers were housed individually in raised crates to facilitate collection of urine and feces. The adaptation period was for 14 days, 2 days for sampling and 7 days for resting the animals. The additive significantly reduced both rumen (p<0.01) and rectal temperatures (p<0.001) without depressed feed intake. There were interactions (p<0.01) between energy level and additive on ruminal temperature. Neither additive nor energy level had an effect on total VFA concentration. The additive however, significantly increased (p<0.01) propionate and subsequently had lower acetate:propionate (A/P) ratios than non-additive supplementation. High concentrate diets had significantly lower pH. Interactions between energy and additive were observed (p<0.01) in ammonia nitrogen production. Supplementation of diets with the additive resulted in lower rumen and rectal temperatures, hence the additive showed promise in alleviating undesirable effects of heat stress in cattle.

• 한국식품영양과학회지
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• 제14권3호
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• pp.235-243
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• 1985

A survey of 113 children, aged 4 to 6 years, of the San Cheon a day care center, located in the upland, over populated, poor area of Seoul City, was conducted from July 28 to September 6, 1982, to investigate the dietary and nutritional status, and prevalence of parasitic inpection. House size was 10.1 Pyung; number of households per house, 3.1; number of family member per household, 4.8; and number of family members living together per room, 3.7; on the average. Only 49% of households possess own houses and the others live in the rented houses. About 40% of mothers were engaged income-producing activities within or outside of the home. Mean values of height, weight, arm circumference, girth of chest, and girth of head ranged from 98.4 to 102.2% of KIST mean. However, 13% of the subjects were assessed as undernutrition for 'weight for height'. Mean value of hemoglobin was $12.9{\pm}2.9\;g/dl$ and mean hematocrit value was $35.2{\pm}5.5%$; 17.9% of the subjects were proven to be anemic according to the criteria of the WHO. The positive prevalence of parasitic inpection was 3.3%, significantly lower than that observed in any other area, probably because of community parasitic control project. Intakes of energy and nutrients except thiamin and ascorbic acid were far below RDAs. Carbohydrates for energy provided 71. 2 to 73.8% of total energy intake; protein accounted 11.3 to 12.2%; fat provided 14.5 to 16.6%. Energy intake was divided among breakfast, lunch, evening meal and snack, on the average, in a percentage of 22.0; 23.4; 24.4; 30.2. There was significant correlation between pattern of food consumption and nutrient intakes. The nutrient intakes and quality of foods were highly correlated to the maternal factors, especially mother's educational level. The study suggested that development of nutrition guides for mother and children would be needed to improve nutritional status of those young children.

• KIEAE Journal
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• 제9권5호
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• pp.47-52
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• 2009

Currently, the environmental issue is of great urgency and sensitivity to the future of our planet. Global warming caused by increased CO2 concentration has an alarming impact on the earth's fragile environment. Droughts throughout the world are causing crop failures. Wildfires now burn with far greater rage. Melting ice caps and glaciers are causing floods. Sea levels are rising. Warm unseasonable winters are threatening our fragile eco-systems. Global warming is no longer a theory; it is an obvious fact we are confronted with every day, and the only way we can prevent it is to take action now. The need to reduce CO2 emissions and try to become carbon neutral is of national importance and leadership. We have become so reliant on fossil fuels that nearly everything we do generates CO2 emissions; from our modern farming practices to transport, to the electricity used to turn on a light, boil water in a kettle or cook our meals. A reduction of 50% of CO2 emissions can easily be achieved by decreasing the energy amount used. We tracked the carbon footprint throughout the electricity and heating energy use in homes and confirmed the amount of carbon emissions according to its consumptions. In order to reduce the carbon generation from housing constructions, such as Passive House concept of buildings or low energy buildings, we must adjust its applications best fit to our conditions. And technical elements should be applied to improve our conditions, and the methodology should be actively sought. Most of all, each individual's recongnition who uses these elements is more important than any other solutions.

• 대한건축학회논문집:계획계
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• 제35권11호
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• pp.25-34
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• 2019

It is important to design windows in a reasonable way considering the performance characteristics of the elements of the window rather than just to increase the thermal energy performance of the window. In this study, the Heat-transfer Coefficient as insulation performance of the windows and together with the grade of the glass's SHGC (Solar Heat Gain Coefficient) were analyzed to relate to the energy efficiency performance of the building by azimuth angle. Based on this basic study, the Heat-transfer Coefficient of windows and the SHGC rating of glass were applied to the unit plan of apartment building, and the Heating and Cooling Demand were analyzed by azimuth angle. Apartment plan types were divided into 2 types of Non-extension and extension of balcony. The designPH analysis data derived from the variant of the Heat-transfer Coefficient and SHGC, were put into PHPP(Passive House Planning Package) to analyze precisely the energy efficiency(Heating and Cooling Demands) of the building by azimuth angle. In addition, assuming the 'ㅁ' shape layout, energy efficiency performance and potential of PV Panel installation also were analyzed by floors and azimuth angle, reflecting the shading effects by surrounding buildings. As the results of the study, the effect of Heat Gain by SHGC was greater than Heat Loss due to the Heat-transfer Coefficient. So it is more effective to increase SHGC to satisfy the same Heating Demand, and increasing SHGC made possible to design windows with low Heat-transfer Coefficient. It was also revealed that the difference in annual Heating and Cooling Demands between the low, mid and high floor households is significantly high. In addition to it, the installation of PV Panel in the form of a shading canopy over the window reduces the Cooling Load while at the same time producing electricity, and also confirmed that absolute thermal energy efficiency could not be maximized without controlling the thermal bridge and ventilation problems as important heat loss factors.

• 동아시아식생활학회지
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• 제13권4호
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• pp.267-283
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• 2003

1920~30년대 일제 하 개성 소년형무소를 비롯한 조선내 형무소의 주식공급량과 대만 신죽 소년형무소 및 프랑스 후레누 감화원, 독일 모아비트 구치소간의 영양조사 자료를 통해 당시 세계공황과 일본의 식량난 속에서 수형인의 식생활 실태를 재검토한 결과를 다음과 같다. 1. 1920년대 조선내 형무소의 주식공급상태 1) 식사가 12등급으로 나누어 제공되었으며 급여열량의 차이로 볼 때 활동정도에 따라 구분하였을 것이다. 목포형무소 1등급이 6045.0 ㎉, 마산형무소 12등급이 1855.8 ㎉로 각 형무소의 잡곡사용비유과 식이등급에 따라 열량공급량의 차이가 큰 것을 알 수 있다. 2) 단백질, 지방, 탄수화물의 평균 열량비가 20.0 : 20.2 : 59.8로 단백질의 공급량이 의외로 높은데 이것은 주식 중 콩의 비율이 높기 때문이다. 개성형무소를 제외하고 주식 중 콩의 사용비율은 20~60%이다. 주식에서의 단백질의 양이 높다하더라도 모두 식물성단백질이지만 다른 곡물에 부족한 lysine에 대한 보충작용의 효과가 컸을 것으로 기대된다. 3) 콩을 공급하지 않은 개성소년형무소는 단백질과 지방의 열량비가 각각 8.3%, 8.1%로 낮고 탄수화물의 공급량이 높아 성장기 소년 수형인에게는 부적절하다고 사료된다. 2. 각 형무소의 영양공급량의 종합적 비교 대만 프랑스, 독일 형무소와 본 논문의 전보로 수행된 (Kim CH 2003) 조선 경성형무소의 영양상황을 종합적으로 파악하기 위하여 중등활동을 하는 수형인에게 공급된 영양량으로 비교하면 다음과 같다. 1) 경성형무소 중등활동 수형인에게 공급된 열량은 1일 3966.5 ㎉, 단백질, 지방, 탄수화물의 열량비는 18.9 : 16.6 : 64.5로 단백질은 약간 높고 지방은 약간 낮으나 3대 영양소의 균형정도는 양호하다고 볼 수 있으며 오히려 총열량이 너무 높은 것으로 사료된다. 2) 대만 신죽 소년형무소에서는 주식은 쌀과 고구마를 7:3으로 혼합하여 6등급으로 구분하여 공급하였으며 부식은 1주일 cycle menu로 작성되었다. 열량섭취량은 1등급에서 2862.9 ㎉, 6등급에서 1388.9 ㎉로 성장기 소년 수형인에게는 충분한 공급이라고 할 수 없다. 단백질과 지방의 열량 섭취량도 적으나 돼지고기, 돼지기름, 잡어, 유부등의 음식을 제공하므로 동물성 단백질과 지방이 어느 정도 공급되었을 것이다. 3) 프랑스 후레누 감화원과 독일 모아비트 구치소는 1일 총열량섭취량이 각각 2771.3 ㎉, 2678.7 ㎉로 당시 열량권장 기준으로 간주되었던 3000 ㎉, 현재 중등활동 성인열량권장량인 2500 ㎉ 어느 쪽으로 비교해도 적정량이 공급되었다고 할 수 있으며, PFC 비율은 후레누 감화원에서 16.2 : 12.0 : 71.8로 지방이 부족하고, 모아비트 구치소에서는 12.4 : 14.3 : 73.3으로 단백질과 지방이 약간 부족하다고 볼 수 있다. 4) 법무부 급식관리위원회의 수용자 급식기준과 각 형무소의 보통활동 수형자를 위해 공급하는 영양량을 종합적으로 비교해보면 총열량 공급량은 조선 경성형무소(Kim CH 2003)에서는 3966.5 ㎉로 급식기준열량의 159.9%로 공급량이 높았으며, 대만 신죽 형무소에서는 소년 수형자임에도 89.6%만을 공급하고 있었다. 프랑스와 독일은 각각 110.9%, 107.1%로 급식기준을 조금 넘는 적정열량에서 가까운 양을 공급하였다고 할 수 있다. 일제하의 조선, 세계공황 이후 식량이 극도로 부족한 상황에서 대만, 유럽의 프랑스와 독일 모두 단체로 수용되어 있는 수형인들에게 적정영양량을 찾기 위해 노력하였다는 것을 알 수 있다. 다만 조사된 것이 계획에 불과한 것이 아니었는지 의문시된다.

• 에너지공학
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• 제25권2호
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• pp.94-100
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• 2016

에너지저장장치(ESS)는 전력수급 불균형 해소, 신재생에너지의 출력안정, 주파수 조정용 등 전력공급 안정성 향상 및 효율적 전기에너지사용 등에 기여하는 중요자원으로, 전세계적으로 '23년까지 '14년 설치용량의 약 30배가 증가한 55.9GWh의 보급이 전망되고 있다. 이와 같이 급증하는 세계시장에서 국내 ESS 업계의 경쟁력 확보를 위해서는 자국내 설치실적(Track Record) 확보가 필요한데, 우리나라는 주파수 조정용(FR용(用))과 그간 지속되어 왔던 전력수급 불균형 상황에 대비하기 위한 부하이동용 중심으로 ESS를 보급하여 왔다. 하지만, 주파수 조정용의 경우 통상적으로 화력발전소 정격용량의 약 5% 범위에서 설치효용이 발생하는 것으로 평가되고 있어, 화력발전이 비약적으로 증가하지 않는 한 국내 시장의 확장성이 부족하다고 할 수 있으며, 여유로운 예비력 확보정책에 따라 부하이동용에 대해서도 보급필요성이 저하되고 있는 바, 새로운 방식의 보급확대 대상이 필요하다고 할 수 있다. 유망한 신규보급대상은 간헐적 출력의 약점은 있으나, 신기후체제 대응과 산업육성을 위해 지속적으로 추진예정인 신재생에너지와의 연계설치를 통해 신재생에너지의 출력을 안정화 하고, 신재생에너지 발전량의 계통투입시기 조절을 통한 이산화탄소 저감효과를 기대할 수 있는 분야라고 할 수 있다. 본 연구에서는 향후 에너지정책의 최대 화두인 신기후체제 대응을 위한 온실가스 감축수단을 활용할 수 있도록, 태양광 연계형 ESS 충방전모드를 온실가스 저감효과를 고려토록 설계한 후, 투자유도를 위한 REC 가중치 산정방법에 대한 정책대안을 제시하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.996-1001
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• 2006

Automatic washing machines have been improved and popularized steadily since the first electric washing machine was produced in the early 1900's. Appliance industry has tried to obtain the performance of washing machine with large capacity, high energy efficiency, low vibration and low noise levels. As the installation peace of a washer becomes closer to the living space, vibration and noise problems become more important challenges. In general, a washing machine has four legs to support its body. Four legs of the washing machine should be attached on a floor. If not so, it may cause severe vibration or walking in the spin-drying process. Unfortunately, the floor of an ordinary house is bumpy in general, and the consumers will not accept bolting washing machines to a foundation; moreover, sometimes they move the location of their washing machines to utility rooms or bath rooms or kitchens and don't care for leveling the legs exactly. In this study, we devise an auto-leg system that prevents the occurrence of abnormal vibration and walking of washing machines. It is simply composed of a spring and a friction damper. Some experiments are implemented to show the dynamic characteristics of the three-dimensional auto-legged washing machine model that is located on the even or uneven ground. A spring parameter is optimized to adjust the length of the auto-leg system automatically up to 10 mm irregularity, and the friction damper is designed to decrease a resonance induced by the spring of the auto-leg system. Some numerical results show that placing the proposed auto-leg system in a washing machine makes good performance with low vibration, as well as low noise, regardless of the unevenness of the floor.

• Journal of Radiation Protection and Research
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• 제45권3호
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• pp.117-129
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• 2020

Background: Radiation portal monitors (RPMs) involving plastic scintillators installed at the border inspection sites can detect illicit trafficking of radioactive sources in cargo containers within seconds. However, RPMs may generate false alarms because of the naturally occurring radioactive materials. To manage these false alarms, we previously suggested an energy-weighted algorithm that emphasizes the Compton-edge area as an outstanding peak. This study intends to evaluate the identification of radioactive sources using an improved energy-weighted algorithm. Materials and Methods: The algorithm was modified by increasing the energy weighting factor, and different peak combinations of the energy-weighted spectra were tested for source identification. A commercialized RPM system was used to measure the energy-weighted spectra. The RPM comprised two large plastic scintillators with dimensions of 174 × 29 × 7 ㎤ facing each other at a distance of 4.6 m. In addition, the in-house-fabricated signal processing boards were connected to collect the signal converted into a spectrum. Further, the spectra from eight radioactive sources, including special nuclear materials (SNMs), which were set in motion using a linear motion system (LMS) and a cargo truck, were estimated to identify the source identification rate. Results and Discussion: Each energy-weighted spectrum exhibited a specific peak location, although high statistical fluctuation errors could be observed in the spectrum with the increasing source speed. In particular, ¹³⁷Cs and ⁶⁰Co in motion were identified completely (100%) at speeds of 5 and 10 km/hr. Further, SNMs, which trigger the RPM alarm, were identified approximately 80% of the time at both the aforementioned speeds. Conclusion: Using the modified energy-weighted algorithm, several characteristics of the energy weighted spectra could be observed when the used sources were in motion and when the geometric efficiency was low. In particular, the discrimination between ⁶⁰Co and ⁴⁰K, which triggers false alarms at the primary inspection sites, can be improved using the proposed algorithm.