• International Journal of Air-Conditioning and Refrigeration
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• 제6권
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• pp.27-35
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• 1998

An experimental study was performed to investigate the optimum cycle of an inverter heat pump as a function of frequency. The performance of the inverter heat pump with the rated cooling capacity of 4,141 W(3,550kcal/h) was measured with a variation of frequency, indoor and outdoor temperature, and length of capillary tube in the psychrometric test room. As a base case, the inverter heat pump with the standard capillary length of l,000mm(optimum size for the frequency of 60Hz) and ASHRAE Test condition "A" was tested by varying frequency from 30Hz to 80Hz. Then, the optimum cycles were investigated by varying the length of capillary tube at each frequency level of 30, 60 and 80Hz. Based on the experimental data, the change of system characteristics between the optimum and the base case were analyzed for each selected frequency level. Generally, for low frequency level(30Hz), the longer length of the capillary tube compared with the standard size showed the higher energy efficiency ratio(EER), while for high frequency level(80Hz) the shorter length of the capillary tube showed the higher EER.

• 콘크리트학회논문집
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• 제18권6호
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• pp.801-809
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• 2006

기존의 에폭시 수지는 많은 우수한 성질을 갖고 있음에도 불구하고, 주제와 경화제의 2성분 혼합의 복잡성, 높은 폴리머 시멘트비에 따른 경제성 등이 사용성을 제약하고 있다. 여기에서 저자들은 에폭시 수지가 경화제를 첨가하지 않아도 시멘트 모르타르의 수화에 의해 생성되는 알카리 성분에 의해 경화할 수 있다는 것을 알아냈다. 본 연구는 기존의 경화제 무첨가 에폭시 시멘트 모르타르의 연구 결과를 기초로 하여 1년간 실내외에 노출하여 내후성을 평가하였다. 다양한 폴리머 시멘트비로 만든 에폭시 시멘트 모르타르를 제작하여, 노출기간 28일, 6개월, 1년에 대한 중량변화율, 휨강도 및 압축강도, 흡수율, 중성화 깊이를 측정하였으며, 세공입경 분포와 내부 미세조직 구조 등을 관찰하였다. 시험 결과, 경화제를 첨가하지 않아도 에폭시 시멘트 모르타르의 내후성은 기존의 경화제를 첨가한 경우에 비해 역학적 성질 및 내구성 면에서 동등 이상으로 우수하였으며, 이상적인 경화제 무첨가 에폭시 시멘트 모르타르의 폴리머 시멘트비는 10% 또는 20%로 제안할 수 있었다.

• 한국환경보건학회지
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• 제50권1호
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• pp.6-15
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• 2024

Background: People's activities have been restricted due to the COVID-19 pandemic. These changes in activity patterns may lead to a decrease in fine particulate matter (PM_2.5) concentrations. Additionally, the level of population exposure to PM_2.5 may be changed. Objectives: This study aimed to analyze the impact of population movement and meteorological factors on the distribution of PM_2.5 concentrations before and after the outbreak of COVID-19. Methods: The study area was Guro-gu in Seoul. The research period was selected as January to March 2020, a period of significant population movement changes caused by COVID-19. The evaluation of the dynamic population was conducted by calculating the absolute difference in population numbers between consecutive hours and comparing them to determine the daily average. Ambient PM_2.5 concentrations were estimated for each grid using ordinary kriging in Python. For the population exposure assessment, the population-weighted average concentration was calculated by determining the indoor to outdoor population for each grid and applying the indoor to outdoor ratio to the ambient PM_2.5 concentration. To assess the factors influencing changes in the ambient PM_2.5 concentration, a statistical analysis was conducted, incorporating population mobility and meteorological factors. Results: Through statistical analysis, the correlation between ambient PM_2.5 concentration and population movement was positive on both weekends and weekdays (r=0.71, r=0.266). The results confirmed that most of the relationships were positive, suggesting that a decrease in human activity can lead to a decrease in PM_2.5 concentrations. In addition, when population-weighted concentration averages were calculated and the exposure level of the population group was compared before and after the COVID-19 outbreak, the proportion of people exceeding the air quality standard decreased by approximately 15.5%. Conclusions: Human activities can impact ambient concentrations of PM_2.5, potentially altering the levels of PM_2.5 exposure in the population.

• 한국동물학회지
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• 제13권2호
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• pp.51-56
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• 1970

Studies on the feeding and resting behavior of Culex pipiens pallens, a possible vector of Japanese encephalitis in Korea, was carried out at Kobu-Ri, Kobu-Myon, Chongup Kun. Cholla Pukdo in 1967. 1. Indoor and outdoor human biting collections showed that 47.3 per cent Culex pipiens pallens were collected indoors and 52.7 per cent outdoors. 2.Feeding occurred throughout the night from dusk to dawn, with the peak period from 23:00-24:00 hours outside the house and from 24:00-01:00 hours inside. 3. Culex pipiens pallens females preferred man for their blood feeding to domestic animals. The results of human and cow biting collections showed that the feeding ratio between man and cow was 2.1 to 1. As to the feeding preference to the domestic animals, the ratio among cow, pig and horse was 7.3 to 5.1 to 5.4 4. Daytime resting collections showed that large numbers of Culex pipiens pallens females rest inside the house, especially in the bed room and the chicken pen. As temperatures increased, fewer mosquitoes resting indoors and more mosquitoes rest ing outdoors were caught. By means of sweep-net collections at outdoors resting places, a small number of Culex pipiens pallens mosquitoes were caught in such places as grass fields, vegetable fields, barley fields, bean fields, culverts, bomb shelters, and so on. A comparison between number of mosquitoes collected resting during the day in bedrooms and verandahs with resting collections in the same places at night showed that more mosquitoes were present at night. It was observed that the majority of the unfed females rested before feeding at night.

• 한국통신학회논문지
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• 제35권1C호
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• pp.24-32
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• 2010

본 논문에서는 버려지거나 없어진 객체를 검출하는 시스템에 대해 연구하였다. 전경과 배경을 분리한 다음, 정적인 영역에 대한 검출을 통하여 방치되거나 제거된 물체를 검출하였다. 정적인 영역에 대한 검출 방법을 제안하고 히스토그램의 비교를 통해 방치, 제거 정보를 추출하였다. 제안된 방법은 CCTV 카메라의 입력 영상에 대하여 PC 및 DSP 칩을 이용하여 실시간 처리를 하였으며 DSP칩을 활용하였기 때문에 수정이 용이하다. 제안된 시스템에 대한 성능을 검증하기 위해 저, 중, 고의 복잡도에 따라 실험하였으며, 신뢰성 있는 검증을 위해 각 10회의 반복 수행을 하였다. 실험 결과, 복잡도가 낮거나 보통인 경우는 높은 객체 변화 검출률을 보였으며 매우 혼잡한 경우에는 환경적인 요인의 이유로 검출률이 상대적으로 낮은 것을 확인할 수 있었다. 이 원인은 복잡도가 높아짐에 따라 검출률이 낮은 것은 이동하는 객체들로 인해 방치된 객체의 폐색이 반복되기 때문이었다. 향후 이러한 문제의 해결을 위해 매우 복잡한 환경에서의 폐색에 대한 추가적인 연구와 강건한 정적 영역의 판단 방법에 대해 연구할 것이다.

• 한국입자에어로졸학회지
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• 제6권1호
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• pp.9-20
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• 2010

This study examined the concentration level of the major air pollutants in public transportation. The study was conducted between February 2009 and March 2008 at Suwon-Yeosu line in Korea. $PM_{10}$ concentration level was $100{\mu}g/m^3$ on average. The $PM_{2.5}$ to PM10 ratio in transport is 0.37, which was lower than the results published by other researches. The result also demonstrated that outdoor $PM_{10}$ concentration was about 56~60% level compared to that of the cabin. $CO_2$ concentration level in the cabin was 1,359ppm, which does not exceed 2,000ppm, which is the guideline concentration level according to the Ministry of Environment. $CO_2$ concentration level in the cabin was $CO_2=23.4{\times}N+460.2$, and about 23.4ppm in $CO_2$ concentration level increased every time one passenger was added on. The experiment conducted on the train demonstrated that the average $PM_{10}$ concentration level was $100{\mu}g/m^3$ in case of the reference cabin while average $PM_{10}$ concentration level of the modified vehicle was $68{\mu}g/m^3$. Likewise, effect of the particle reduction device for the reduction of $PM_{10}$ concentration level was approximately 21%. Meanwhile there was almost no difference in the concentration level between reference and modified cabin in case of $PM_{2.5}$. Using zeolite as an adsorbent was made to reduce the $CO_2$ concentration level in the cabin. Number of passengers was factored in, to calculate the effect of the adsorption device, which demonstrated that about 36% of $CO_2$ concentration level was reduced in the modified cabin effect of the $CO_2$ reduction device. This research analyzed the current status concerning the quality of air in the public transportation and technologies were developed that reduces major air pollutants.

• 농촌계획
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• 제18권2호
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• pp.57-68
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• 2012

This study is to suggest the improving methods for rural community centers by analysis of 30 community centers in Samnangjin-eup, Miryang city, Gyeongnam. To fulfill this purpose, the facilities, usable condition and management system were examined. The user needs and level of satisfaction were also investigated through the interviews with 858 citizens. The average size of the centers is $96m^2$, and 73% of them are one-story buildings. Women use the community center more frequently than men in ratio of 6:4. 43.4% of interviewees visit the center 1 or 2 times a month, but on the other hand 27.4% of them use the center almost every day. Recess is surely the main purpose, and health care and community meeting are next two reasons. 67.8% and 72.4% of them are not satisfied with the inside and outside of the community center respectively. The interview results demonstrate that the most important issue is the lack of facilities. To improve the community centers in Samnangjin-eup, first of all, various kinds of indoor and outdoor facilities must be equipped. Secondly, considering the center is the core of rural community life, the qualitative improvement in accommodation is also needed as well as facility diversification. The efficiency of space utilization is another issue. A small piece of land or abandoned space must be utilized. Moreover, it is very critical that the users are mostly seniors and elders, so improvements of facilities will be executed in terms of safety and convenience. Finally, administrative and financial support should be made for the people, so as to maintain the the rural community center on their own.

• 보존과학연구
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• 통권35호
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• pp.25-44
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• 2014

이 연구에서는 유물 전시관을 대상으로 Active type과 Passive type에 의한 VOCs의 측정 분석법을 사용하여 전시실 내 외의 연중, 계절별 농도를 조사하고 측정방법에 따른 농도 비교를 통해 측정방법 간의 상관성을 비교하였다. 그 결과, Active type에 의한 전시실 TVOC의 연중 평균 농도는 $906.5{\mu}g/m^3$으로 대부분 조사 기간 동안 환경부 기준을 1.8배 이상 초과하였다. Active type에 의한 전시실의 ${\Sigma}VOCs$ 농도는 Passive type 보다 높았다. 일부 VOCs는 시간의 경과에 따라 감소하나 일시적인 상승 경향을 나타내기도 했다. Active type에 의한 전시관의 연평균 I/O비는 TVOC 9.0, ${\Sigma}VOCs$는 34.0으로 조사되어 ${\Sigma}VOCs$가 전시실 내부에서 다량 발생하는 것을 확인하였다. 두 방법 간의 상관성 분석 결과, ${\Sigma}VOCs$의 상관계수는 0.367이었으며 톨루엔은 0.567로 두 분석 방법 간의 연관성이 가장 큰 것으로 조사되었다.

• 대한의용생체공학회:의공학회지
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• 제33권1호
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• pp.25-31
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• 2012

The audio vision system was developed for visually impaired people and usability was verified. In this study ten normal volunteers were included in the subject group and their mean age was 28.8 years old. Male and female ratio was 7:3. The usability of audio vision system was verified by as follows. First, volunteers learned distance of obstacles and up-down discrimination. After learning of audio vision system, indoor and outdoor walking examination was performed. The test was scored by ability of up-down and lateral discrimination, distance recognition and walking without collision. Each parameter was scored by 1 to 5. The results were 93.5 +- SD(ranges, 86 to 100) of 100. In this study, we could convert visual information to auditory information by audio-vision system and verified possibility of applying to daily life for visually impaired people.

• 한국정보통신학회논문지
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• 제20권4호
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• pp.691-697
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• 2016

본 논문에서는 UWB 통신 시스템에 적합한 안테나를 제안하였으며, 특정 구간에서 위치 인식에 적합한 특성을 만족하였다. 제안된 테이퍼드 슬롯 안테나는 Ansys사의 HFSS 시뮬레이션 툴을 통하여 최적화 설계되었으며, 유전율 4.5, 손실 탄젠트 0.0035, 두께 1.62 mm를 갖는 Taconic TRF-45 기판으로 제작되었다. 테이퍼드 슬롯 안테나는 주파수 영역에서의 반사계수 및 정재파비, 방사패턴 등을 분석하였다. 제작된 테이퍼드 슬롯 안테나의 임피던스 대역폭은 3.8 ~ 8.9 GHz 대역에서 5.1 GHz 대역폭을 보였으며, 안테나의 E-평면과 H-평면에서 방사패턴은 특정 구간에서 실내 외 위치 인식에 적합한 지향성의 특성을 만족하였다. 안테나 이득은 시뮬레이션에서 6 GHz 대역에서 7.4 dBi이며, 측정 결과는 6 GHz 대역에서 7.6 dBi의 최대 이득을 보인다. 제안된 테이퍼드 슬롯 안테나는 시뮬레이션과 측정 결과는 다소 차이가 있지만 UWB 통신 시스템의 규정을 만족하였다.