• 농업과학연구
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• 제37권2호
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• pp.295-302
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• 2010

Electro-hydraulic transmission (HST) and an electronic control system was designed, and performance of the components were investigated through indoor tests. When input values for HST swash plate control were given at 3 levels (5, 10, 13 degrees) in forward and reverse directions, the errors were less than 0.6 degrees. Response time was in ranges of 0.14 ~ 0.16 s and 0.16 ~ 0.2 s for forward and reverse direction controls while driving, and the values were 0.23 ~ 0.25 s and 0.18 ~ 0.23 s at static condition, respectively. Similar experiments for left and right steering resulted errors less than 0.5 degrees. Resonse time was in ranges of 0.16 ~ 0.22 s and 0.11 ~ 0.23 s for left and right turns while driving, and the values were 0.07 ~ 0.21 s and 0.09 ~ 0.14 s at static condition, respectively. From frequency response experiments, control system appeared to follow sine waves appropriately at frequencies less than 0.8 Hz with gain of 0.11 dB and 0.09 dB for forward and reverse direction controls, respectively, and the gain decreased above the frequency. Phase difference showed a gradual increase and were less than 45 degree up to 0.8 Hz. Similar experiments for left and right streering showed that the control system appeared to follow sine waves appropriately at frequencies less than 0.8 Hz with gain of 0.28 dB and 0.26 dB for left and right steering controls, respectively, and the gain decreased above the frequency. Phase difference showed a gradual increase and were less than 45 degree up to 0.8 Hz, which was the same as for the forward and reverse controls.

• Journal of the Korean Wood Science and Technology
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• 제35권6호
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• pp.100-107
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• 2007

현대인들은 실내에서 보내는 시간이 하루 중 90% 달하는 것을 간주할 때 실내의 공기는 현대에게 중요한 요소임을 알 수 있다. 1960년대 이후로 산업이 급격히 발전하면서 건축 재료는 천연재료에서 화학물질을 기본으로 하는 재료로 변하게 되고 에너지 절약의 대책으로 건물의 기밀도를 높임으로써 건축자재에서 발생하는 유해물질이 현대인에게 악영향을 미치기 시작했고 이런 요소들이 근원이 되어 새집증후군을 유발하게 되었다. 생활수준이 높아지면서 사람들은 건강에 대한 관심도 높아지게 되고 보다 유익한 친환경 건축자재를 요구하게 되었다. 본 연구에서는 황토, 물, 수지, 경화제, 무기물 충전제를 이용한 친환경 황토 마감재를 개발하였고 한국형 목조 주택 내장벽에 사용할 수 있는 최적의 비율을 연구하였다. 그리고 이런 황토 마감재가 실내벽에 사용 시 요구물성인 내잔갈림성, 내세척성, 내충격성, 부착강도를 측정하였고 황토마감재의 특성인 원적외선 실험과 포름알데히드, TVOC 방산 농도를 통하여 친환경성에 대한 평가를 하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제32권5호
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• pp.657-664
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• 2019

Objective: This study was performed to evaluate whether cold ambient temperature and dietary rumen-protected fat (RPF) supplementation affect growth performance, rumen fermentation, and blood parameters in Korean cattle steers. Methods: Twenty Korean cattle steers (body weight [BW], $550.6{\pm}9.14kg$; age, $19.7{\pm}0.13months$) were divided into a conventional control diet group (n = 10) and a 0.5% RPF supplementation group (n = 10). Steers were fed a concentrate diet (1.6% BW) and a rice straw diet (1 kg/d) for 16 weeks (January 9 to February 5 [P1], February 6 to March 5 [P2], March 6 to April 3 [P3], and April 4 to May 2 [P4]). Results: The mean and minimum indoor ambient temperatures in P1 ($-3.44^{\circ}C$, $-9.40^{\circ}C$) were lower (p<0.001) than those in P3 ($5.87^{\circ}C$, $-1.86^{\circ}C$) and P4 ($11.18^{\circ}C$, $4.28^{\circ}C$). The minimum temperature in P1 fell within the moderate cold-stress (CS) category, as previously reported for dairy cattle, and the minimum temperatures of P2 and P3 were within the mild CS category. Neither month nor RPF supplementation affected the average daily gain or gain-to-feed ratio (p>0.05). Ruminal ammonia nitrogen concentrations were higher (p<0.05) in cold winter than spring. Plasma cortisol concentrations were lower (p<0.05) in the coldest month than in the other months. Serum glucose concentrations were generally higher in colder months than in the other months but were unaffected by RPF supplementation. RPF supplementation increased both total cholesterol (p = 0.004) and high-density lipoprotein (HDL) concentrations (p = 0.03). Conclusion: Korean cattle may not be significantly affected by moderate CS, considering that the growth performance of cattle remained unchanged, although variations in blood parameters were observed among the studied months. RPF supplementation altered cholesterol and HDL concentrations but did not affect growth performance.

• 농업과학연구
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• 제47권1호
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• pp.43-58
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• 2020

Mulching plastic is used for the purpose of maintaining soil temperature, moisture, and weed and pest prevention in agriculture. Any remaining plastic after use may contaminate the soil and damage crop growth. To solve this problem, mulching plastic wrappers have been studied and developed, but the actual use rate is quite low due to their poor performance and frequent tearing of the plastic on the field. In this study, we developed a tractor attachable mulching plastic wrapper to minimize the tearing of the mulched plastic. The developed mulching plastic wrapper consists of hydraulic motors and pumps, valves, a microcontroller, and sensors. The collecting speed of the plastic mulch was calculated considering the tractor's travel speed and the radius of the collecting drum. A proportional controller was designed to control the rotating speed of the hydraulic motor as the plastic was wound around the collection drum and the radius increased. The performance of an indoor experiment was quite promising because the difference between the collecting speed predicted by the calculation and the actual collecting speed was 2.71 rpm. Based on a field verification test, the speed difference was max. 14.28 rpm; thus, the, proportional integral derivative (PID) controller needs to be considered to control the drum speed precisely. Another issue was found when the soil covered at the edge of the plastic was hardened or the road surface was uneven, the speed control was unstable, and the plastic was torn. In future research, vibrational plows will be equipped to break-up the harden soil for collecting the plastic smoothly.

• 한국주거학회논문집
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• 제23권5호
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• pp.51-60
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• 2012

Large-scale urban developments with increasing population and expansion of industrial facilities have destroyed the ecosystem. Consequently, the importance of vertical farm as a form of urban agriculture is increasing. However, such problems of vertical farms as economy and lack of awareness of residents are being raised. Firstly, this study derived types of vertical farm that are applicable to residential spaces through an examination of vertical farm buildings, and then inferred assessment items for a questionnaire survey for the development of u-services. Secondly, based on the issues deduced from the survey, u-services needed in vertical farm buildings were derived to use them as the basic data when we plan for a ubiquitous vertical farm building in residential space in the future. As result, the following uservices of ubiquitous vertical farm were proposed: u-notification service about the condition of crops from the aspect of growth management based on ubiquitous technology, remote/automatic control u-services, harvest information u-service for harvest management, recipe information u-service, and indoor air quality monitoring u-service, indoor environment adjusting u-service, and farm environment control u-service. Considering that many new buildings in Korea are residential buildings and many high-rise buildings are being planned, studies on vertical farm buildings must be continued.

• 인간식물환경학회지
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• 제24권1호
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• pp.29-38
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• 2021

Background and objective: The physical environment where children spend most of their time is closely associated with their emotional development. To improve the emotional health of children, the introduction of natural elements in the indoor space has been suggested, the benefits of which have been shown in preliminary studies. This study aims to examine the effects that a biowall - a wall installation - in a classroom has on the emotional health of children in kindergarten. Methods: A total of four biowalls were separately installed in four kindergarten classrooms at a school in Seoul, South Korea, and the 60 children in these classrooms participated in the study. We assessed the children's emotional intelligence (via an Emotional Intelligence Rating Scale), resilience (via the Devereux Early Childhood Assessment), and eco-friendly attitudes (via the Children's Attitudes Toward Scale) before the installation of the biowalls and then again 3 months later. Results: The children's emotional intelligence, resilience, and eco-friendly attitudes had been significantly improved after the installation of the biowalls (p = .01). The sub-categories of the children's emotional intelligence and resilience were also significantly improved (p < .001). Conclusion: This study demonstrates the potential of biowalls-as an indoor environmental factor-in promoting the healthy emotional development of children. By bringing natural elements into indoor classroom settings, biowalls appear to increase children's direct/indirect contact with nature. To extrapolate the results of the study to the general population, future studies should be conducted with broader age groups.

• 농촌계획
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• 제20권3호
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• pp.143-154
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• 2014

For the purpose of drawing a representative type of utilizing idle farmlands, this study collected and analyzed newspaper articles about cases of utilizing idle farmlands in the past decade using Internet search engines. Prior to this, it clarified a concept of idle farmlands to raise accuracy of searching articles, and selected NAVER as a search engine. It set "idle farmland", "abandoned land", and "utilizing" as basic search words in search option, and also set search period from 1st of January in 2004 to 31st of December in 2013. This study primarily searched 1,593 articles, and extracted 165 articles excluding overlapped and unrelated articles. Furthermore, it investigated extracted articles by date, media, headline, content of use, region(province), particular area(city and country), main agent, item and keyword 1, 2, 3 for proper use. This study also examined frequencies by year according to indoor and outdoor environment as well as regional differences through frequencies by regional groups and chronology. Furthermore, it drew a diagram of frequency flow of keyword 2, 3 with each keyword 1 as the central figure in order to draw various types of using idle farmlands. Through the diagrams, this study drew 9 using types such as (1) community service. agriculture type, (2) high income. agriculture type, (3) sightseeing. landscape. agriculture type, (4) livestock. agriculture type, (5) weekend farm type, (6) high income. woodland type, (7) ecology. landscape. woodland type, (8) agricultural work-study type, (9) ecological environment type.

• Journal of the Korean Wood Science and Technology
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• 제48권5호
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• pp.710-721
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• 2020

본 연구에서는 시멘트, 벽돌, 목재를 이용한 건축모형을 이용하여 직경 900 mm의 밀폐된 환경 속에서 3일간 온도와 상대습도 측정을 통하여 건축소재의 종류에 따른 실내 온도 환경에 미치는 영향과 열 이동 특성에 대해서 비교분석하였다. 건축모형 내부에 설치된 물은 실내에 있는 사람을 나타냈으며 사람에게 어떤 영향을 미치는지 평가하고자 사용되었다. 목조 건축모형은 시멘트, 벽돌 건축물 보다 보온성이 높아 열 손실이 가장 낮은 것으로 나타났다. 각각의 건축 모형의 열적 쾌적성은 온도와 상대습도를 이용하여 산출하였으며 목조 건축 모형은 시멘트, 벽돌 건축 모형보다 더 쾌적한 환경을 조성하는 결과를 도출하였다.

• Journal of the Korean Wood Science and Technology
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• 제48권2호
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• pp.217-230
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• 2020

지구온난화로 인한 온실가스 배출 감소에 대한 관심도가 증가하고 있으며, 이 중 온실가스 감축 계획으로 에너지 소비 감소 계획이 제안되고 충족을 위한 건축물이 열관류율 기준이 강화되었다. 한국에서는 소비되는 전체 에너지 중 약 25%는 건축부문에 사용되고 있으며 건물 에너지 소비량 감소를 위한 열전도율이 낮은 건축자재 또는 단열재 개발이 요구되고 있으며, 열전도율이 낮은 목재의 활용 사례도 증가하고 있다. 또한 내부 마감재로 사용될 경우 건물 에너지 소비가 최대 7%까지 감소된다는 선행연구 결과를 바탕으로 본 연구에서는 일반적으로 실내마감재로 사용되는 3가지 유형의 마감재(시멘트, 오동나무, MDF)에 따라 열전달특성 및 열용량을 비교하였다. 본 연구를 통하여 열 이동은 복사열의 형태로 전달되며 오동나무 마감재 사용시 에너지량과 열전달량이 가장 많은 결과로 실내 마감재로 목재 사용 시 건물 내부의 에너지 효율을 향상시킬 것으로 판단된다.

• 한국농공학회논문집
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• 제60권3호
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• pp.71-81
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• 2018

$CO_2$ concentration has a significant effect on quality of cold-stored apples. High indoor $CO_2$ concentrations above 10,000 ppm cause the browning of apples and result in economic loss for farmers. The purpose of this study is to evaluate $CO_2$ concentrations and their distribution in a controlled atmosphere (CA) storage and provide better structural designs to improve the $CO_2$ environment using computational fluid dynamics (CFD) simulations. The CFD model was developed for a real CA storage for apples and applied to investigate the effect of changing the inlet and outlet locations and the aspect ratio of the floor of the CA storage on the spatial distributions of $CO_2$ concentration and the browning of the apples. The lowest $CO_2$ concentrations in existing CA storage with a high aspect ratio of the floor were achieved from the combination of the inlet located at the top of the right side and the outlet located at the bottom of the left side. In modified CA storage with a low aspect ratio, the combination of the inlet and outlet located at top and bottom of left side respectively achieved the lowest $CO_2$ concentrations. The proposed case enhanced the storage performance by reducing total browned apples by 3.6% in storage duration of 210 days. This study is expected to reduce the browning damages of apples in CA storage, and thus greatly prevent economic losses.