• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.793-795
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• 2011

In this paper, an wet diaper sensor system for u-healthcare is implemented and designed. The u-healthcare system of wet diaper sensor consists of sensor node, data-logger/gateway, and server or user terminals. The sensor node includes $NH_3$, humidity, and temperature sensors and TI CC2530 chip, and the data-logger/gateway can connect to a communication network and send the aggregated data from the sensor nodes to a server, and the server can manage the situation of the sensor node and make another analyzed information. Also user terminals can request and obtain the information necessary from the server. The algorithm for detecting wet diaper is proposed, and using the proposed algorithm, the sensitivity for detecting wet diaper is 100%.

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.303-312
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• 2018

This study was conducted to investigate the relationship between the decrease of forest biomass by forest thinning and the change of temperature in the natural forest by measuring forest biomass and temperature before and after forest thinning in the Pusan National University forest where afforestation had been carried out. We intended to investigate the relationship between the forest biomass, estimated by calculating the Basal area, Crown area and Crown volume using the same formula to the same quadrat before and after forest thinning, and the forest temperature. Temperature measurement was carried out on April 20, 2016 through 28 before forest thinning, July 26, 2016 through November 4 around the time of forest thinning, and April 15, 2017 through May 8 after forest thinning. A temperature data logger was installed to point north at the height of 2.0 m above the ground in the center of the quadrat to record data every 10 minutes during the measurement periods. We used the AWS (Automatic Weather Station) data of the Dongnae-gu area located in the nearby city because it was difficult to set the control group since the whole forest was the subject to the forest thinning. The analysis of the relationship between forest biomass change and temperature showed that the change in temperature inside the forest was the greatest in the midday (12:00 - 15: 00) and was highly correlated with the Crown volume in the forest biomass. The temperature increase was much larger (average $1.91^{\circ}C$) 1 year after forest thinning than immediately after forest thinning (average $0.74^{\circ}C$). The comparison of the decrease rate of Crown volume and the increase in temperature showed that the Pitch pine community, which showed the highest decrease of Crown volume by 15.4%, recorded the highest temperature rise of $1.06^{\circ}C$ immediately after forest thinning and $2.49^{\circ}C$ 1 year after forest thinning. The Pitch pine-Korean red pine community, which showed the lowest Crown volume reduction rates with 5.0%, recorded no significant difference immediately after forest thinning but a temperature rise of $0.92^{\circ}C$ 1 year after forest thinning. The results confirmed that the decrease of forest biomass caused by forest thinning led to a rapid increase of the internal temperature. The fact that the temperature increase was more severe after 1 year than immediately after forest thinning confirmed that the microclimate changes due to the removed biomass cannot be recovered in a short time.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.271-273
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• 2010

태양광발전시스템에서 PV모듈이나 어레이의 성능특성 및 성능추정이 요구되고 있다. 태양광 발전 모듈은 장기간 사용 시 환경 요인 등으로 효율이 나빠지며 어레이의 특정 모듈 효율저하는 전체 발전 전력의 감소를 초래하므로 실시간 감시가 필요하다. 이 논문은 태양광 발전 모듈의 발전 전력을 실시간으로 측정하기 위한 것이다. 모듈의 출력을 실시간으로 측정하기 위해 전압, 전류 측정 회로를 제작하고 온도, 일조량 측정 장치를 제작하여 RS485 통신으로 연결하였다. Visual Studio - Basic .Net(2005)과 NI사의 Measurement Studio를 이용하여 실시간 모니터링 프로그램을 제작하였고, 모듈들 사이의 상대적인 발전 출력을 비교하여 효율 저하가 의심되는 모듈을 실시간으로 탐색하였다. 20개 모듈의 직병렬로 구성된 1kW 태양광 발전체에 적용하여 시험한 결과 2개의 모듈에서 성능 저하가 의심되는 결과가 확인되었다.

• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.20-26
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• 2018

This study was conducted to develop a device for measuring the air flow by space variation through monitoring program, which acquires data by each point from each environmental sensor located in the greenhouse. The distribution of environmental factors(air temperature, humidity, wind speed, etc.) in the greenhouse is arranged at 12 points according to the spatial variation and a large number of measurement points (36 points in total) on the X, Y and Z axes were selected. Considering data loss and various greenhouse conditions, a bit rate was at 125kbit/s at low speed, so that the number of sensors can be expanded to 90 within greenhouse with dimensions of 100m by 100m. Those system programmed using MATLAB and LabVIEW was conducted to measure distributions of the air flow along the greenhouse in real time. It was also visualized interpolated the spatial distribution in the greenhouse. In order to verify the accuracy of CFD modeling and to improve the accuracy, it will compare the environmental variation such as air temperature, humidity, wind speed and $CO_2$ concentration in the greenhouse.

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.43-53
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• 2013

Environmental monitoring analysis were analyzed for the period from 1988 to 2007 near King Sejong Station. Extreme environment structure behaviors(Marine Biology Lab.) were evaluated using monitoring sensors developed commercial sensors. Also when installing the sensors ambient environment of the King Sejong Station, to analyze the measured data and the comparative behavior of the structure were analyzed. As a environmental monitoring analysis result at King Sejong Station temperature, sensors were installed to withstand about $-25.6^{\circ}C$ or less and 49.5m/s. They were needed that the height of 225.0cm or more to be installed during the installation. For several monitoring sensors used in Antarctic, temperature, snow and strong winds were very sensitive to the atmospheric environment. Quite often a camouflage(animals and humans) would make it necessary to provide housing for monitoring sensors. Therefore, protection system developed for these sensors were to protect the sensors and data logger. Protection system the newly developed, is economical, easy to install even in harsh environments. Based on the measurement result of the one year, consider electrode applicability of the protection system, it was confirmed that the behavior of the structure is also predictable.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.864-868
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• 2006

댐과 양쪽의 산 능선에 감싸이어 있는 저수지의 모습은 이렇다할만한 특징을 찾아보기가 쉽지 않다. 우리나라의 각지에 건설되어진 다목적댐으로 인해 형성되어진 저수지들을 둘러보아도, 역시 주변의 지형을 자세히 비교해 보기 전에는 구별하기 힘들만큼, 그만큼 외관상으로는 닮아있다. 하지만, 이러한 저수지들이 보여주는 자연현상은 실제로는 너무나도 다양하다. 잔잔한 물 표면의 안쪽에 저마다 눈에 보이지 않는 특성들을 감추고 있으리라 추측해 본다. 하지만, 그 특성을 정량적으로 파악 하기란 좀처럼 쉽지가 않다. 영양염분의 과다 유입으로 부영양화가 초래되면 여기저기서 녹조를 발생 시키고, 또한 홍수나 상류 유역의 토사 붕괴로 인하여 좀처럼 침강되지 않는 미세 입자가 과다 유입되면, 1년 내내 누런 탁수로 몸살을 앓는다. 이처럼, 인간의 눈에 보여 지는 저수지는 '매우 닮은 모습에서 너무나 다른 모습'으로 '계단의 층계변화'와 같은 극단적인 상태 변화만이 파악되어진다. 최근에 들어서, 장비의 발달과 환경에 대한 관심의 고조로 한 달에 한번 많으면 일주일에 한 번씩 현장 조사를 수행하고는 있지만, 지속적으로 저수지를 파악하기 위한 '선형적인 현상'을 보여주기에는 충분하지가 않다. 본 연구에서는, 저수지 수온을 모니터링 함으로서, 홍수와 가뭄과 같은 이벤트 및 계절 변화로 인한 수체의 온도분포를 조사 하였다. 그 방법으로, 자체 개발한 써미스터체인을 용담호의 댐축 지점과 댐축으로부터 상류방향으로 6.6km 떨어진 유입지점의 두 곳에 설치하였으며, 연 중 10분 간격으로 수온데이터를 로거에 저장한 후, 두 달에 한번 정도로 센서 정비 및 데이터 수거를 실시하였다. 그 결과, 우리가 눈으로나 현지관측만으로는 파악할 수 없었던 수체내의 많은 특징을 파악 할 수 있었다.. 중랑천 유역의 소배수구역을 대상으로 연중 발생하는 큰 호우사상에 대해 임의의 강우관측소를 결측지점으로 가정하고 주변의 강우관측소로부터 각각의 방법을 이용해 가중치들을 산정하여 결측지점의 강우량 값을 보정하고자 하였다. 또한 각각의 방법을 이용하여 얻어진 결과에 대해 실측값과 보정값의 오차정도를 평균절대오차법(Mean Absolute Error)과 제곱평균제곱근오차법(Root Mean Squared Error)에 의해 산정하여 보정 방법간의 효율성을 검토하고자 하였다.9년, 그리고 2010년${\sim}$2019년까지 총 4구간으로 나누어 결과를 도출하였으며 예상한 바와 같이 후반기 20년 동안에 세 가지 지표가 취약해 지는 것을 확인할 수 있었고, 특히 2000년부터 2009년까지 10년 동안에는 더욱 취약해짐을 확인할 수 있었다.를 보임에 따라 그 정책적 효과는 때로 역기능적인 결과로 초래하였다. 그럼에도 불구하고 이 연구결과를 통하여 최소한 주식시장(株式市場)에서 위탁증거금제도는 그 제도적 의의가 여전히 있다는 사실이 확인되었다. 또한 우리나라 주식시장에서 통상 과열투기 행위가 빈번히 일어나 주식시장을 교란시킴으로써 건전한 투자풍토조성에 저해된다는 저간의 우려가 매우 커왔으나 표본 기간동안에 대하여 실증분석을 한 결과 주식시장 전체적으로 볼 때 주가변동율(株價變動率), 특히 초과주가변동율(超過株價變動率)에 미치는 영향이 그다지 심각한 정도는 아니었으며 오히려 우리나라의 주식시장은 미국시장에 비해 주가가 비교적 안정적인 수준을 유지해 왔다고 볼 수 있다.36.4%)와 외식을 선호(29.1%)${\lrcorner}$ 하기 때문에 패스트푸드를 이용하게 된 것으로 응답 하였으며, 남 여 대학생간에는 유의한 차이(p<0

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.634-643
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• 2023

Purpose: Underground common duct fires are steadily occurring, and the proportion of property damage is particularly large among property and human casualties caused by fires. Especially, cable fires that occur in common areas can spread vertically quickly and pose a great risk. This paper aims to scientifically analyze the nature of the fire by reproducing the fire through experiments. Method: To analyze the characteristics of cable fires in underground common duct, heat release rate and temperature changes were measured through Room-corner (ISO 9705) test, and the vertical and horizontal propagation of cable fires was quantitatively compared and analyzed. Result: The Room Corner Test (ISO 9705) was used to compare the temperature changes at each data logger point. The results showed that the time it took for the fire to reach the ignition temperature in the horizontal and vertical directions from the center point of the first-tier cable was 589 seconds and 536 seconds, respectively, which means that the vertical fire propagation is 53 seconds faster than the horizontal propagation. This proves that the vertical propagation of fire is relatively faster than the horizontal propagation. The horizontal propagation speed of the fire was also compared for each floor cable tray. The results showed that the third-tier cable propagated at 3.4 times the speed of the second-tier cable, and the second-tier cable propagated at 1.5 times the speed of the first-tier cable. This means that the higher the cable is located, the faster the fire spreads and the larger the fire becomes. Conclusion: This study identified the risks of cable fires and analyzed the risks of vertical fire propagation during cable fires based on the results of the Room Corner Test. Studies to prevent the spread of fire and fire response policies to prevent vertical fire propagation are required. The results of this study are expected to be used to assess the fire risk of common areas and other fires.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.143-151
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• 2022

This study was carried out to investigate quantitative characteristics of the cooling effect in a single-span arch greenhouse with roll-up side vents depending on operation of circulation and exhaust fans during ventilation, in order to suggest a practical strategy regarding installation or operation of forced ventilation systems. The examination was conducted under 3 different ventilation conditions (side vents only, side vents + circulation fans, and side vents + circulation fans + exhaust fans). In each condition, variations of internal and external air temperatures and exogenous environmental factors were recorded during ventilation, and the cooling effects were investigated by comparing the normalized temperature difference (NTD) of each ventilation condition. In the morning time (11:00-12:00), a temporary peak in the temperature difference was observed at the beginning of ventilation regardless of ventilation methods. The time taken to the maximum NTD was decreased from 340 s to 110s, and the NTD was dropped from 1.158 to 1.037 as the more forced ventilation systems were operated. The more operations caused the passing time over specific NTD values reduced by 60% as the time was reduced from 1,030 s to 550 s at NTD = 0.8, 1,610 s to 915 s at NTD = 0.6, and 2,315 s to 1,360 s at NTD = 0.4. The temporary peak in NTD was not observed in the afternoon time (14:00-15:00) but it was dropped as quickly as the ventilation started. Also the more operations resulted in the passing time over specific NTD values reduced by 70% as the time was reduced from 560 s to 345 s at NTD = 0.8, from 825 s to 540 s at NTD = 0.6, and from 1,145 s to 810 s at NTD = 0.4. Conclusively, the intervention of the forced ventilation system is recommended in the morning time or in high thermal conditions to achieve more effective and economical ventilation.