• Journal of The Korean Society of Grassland and Forage Science
• /
• v.27 no.2
• /
• pp.123-128
• /
• 2007

A study was conducted over two years to determine the temperate mixtures of grasses for grazing horses in Jeju, Korea. The experiment field located at 450 m altitude (Jeju Horse Training Center of Korea Racing Association) was divided into 3 different mixtures plots (3 replications) without a fence between treatments, and sown by three main grasses (orchardgrass, perennial ryegrass and timothy). Seven castrated adult horses were kept on pasture from the middle of April to the end of November without supplementary concentrates. The dry matter yield, percentage of grasses intake and botanical composition were determined during the grazing period. Nutrients in grasses and soils were analyzed. The dry matter yield during two-year experimental period was not different among mixtures (11,000-12,000 kg/ha/year). In botanical composition, perennial ryegrass was dominant in all mixtures during spring through early summer season, but faded away during hot summer season. Timothy seemed to be more resistant against a hot or dry weather than other grasses. The percentage of grasses intakes was higher in the mixture of timothy than those in other mixtures. The contents of NDF (neutral detergent fiber) and ADF (acid detergent fiber) were not different among different mixtures. These results indicate that the mixture of timothy, orchardgrass, perennial ryegrass and white clover (20, 5, 5, 2 kg/ha as a seeding rate) can be used for gazing pasture of horses in the high altitude of Jeju.

• Korean Journal of Construction Engineering and Management
• /
• v.16 no.1
• /
• pp.52-63
• /
• 2015

Business facilities among domestic architectures have rapidly been constructed along with domestic economic development. It is an important facility taking the second largest proportion next to apartment buildings among current 31 building types of fire department classification of 2012 year for urban architectures. The expected service life of business facilities is 15 years, but 70% of those in urban areas have surpassed the 15 year service life as of the present 2014. Thus, the demand for urgent rehabilitation of such facilities is constantly increasing due to the aging and performance deterioration of the facilities'main finishing materials. Especially, the business facilities are being used for the lease of company office or private office, and such problems as aging and performance deterioration of the facilities could cause less competitive edge for leasing and real estate value depreciation for the O&M (Operation & Management) agent and the owner, respectively. Therefore, an effective planned rehabilitation as a preventive measure according to the standardized repair rate by the number of years after the construction is in need in order to prevent the aging and performance deterioration of the facilities(La et al. 2001). Nonetheless, domestic repair/rehabilitation standards based on the repair rate are mainly limited to apartment buildings and pubic institutions, resulting in impractical application of such standards to business facilities. It has been investigated and analyzed that annual repair rate data for each finishing material are required for examination of the applicability of the repair rate standard for the purpose of establishment of a repair plan. Hence, this study aimed at developing a repair rate computation model for finishing materials of the facilities and verifying the appropriateness of the annual repair rate for each finishing material through a case study after collecting and analyzing the repair history data of six business facilities. The results of this study are expected to contribute to the planning and implementation of more efficient repair/rehabilitation budget by preventing the waste of unpredicted repair cost and opportunity cost for the sake of the business facilities' owners and O&M agents.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.948-952
• /
• 2009

면적평균강우량을 정확하게 추정하는 것은 수문조사 결과로 생성된 수위-유량관계곡선 검증을 위한 연간 유출율 및 유황분석 시에 매우 중요하다. 면적평균강우량을 산정하는 방법은 일반적으로 산술평균법, 티센법, 등우선법 등이 있는데, 최근 실무에서는 GIS Tool을 이용하여 티센다각형을 작도하고 가중치를 산정하여 관측소별 강우량을 유효강우량으로 변환하여 이용하거나, 평지 또는 좁은 유역의 경우 산술평균법을 적용하고 있다. 그러나 티센법은 지형적인 영향을 고려할 수없고, 산술평균법의 경우 우량계 밀도와 위치, 지형이 고려되지 못한다는 단점이 있기 때문에, 등우선법을 이용하여 면적평균강우량을 산정하는 것이 대부분 산악지역으로 이루어진 국내 현실에 가장 적합하다. 본 연구에서는 수문조사가 이루어지고 있는 낙동강 본류, 댐상류 등 13개 유역의 유역별 면적 평균강우량을 각각 산술평균법, 티센법, 등우선법을 이용하여 산정하였다. 등우선도의 작성을 위하여 관측소별 강우량을 역거리가중법(IDW), RBF, Kriging 기법을 이용하여 강우량의 공간보간을 실시하였으며, 등우선 간격의 영향을 검증하기 위하여 각 보간법 별 등우선 간격을 10mm, 50mm, 100mm로 분할하여 면적평균강우량을 산정하였다. 각 면적평균강우량 산정기법 및 등우선 간격별로 산정된 면적평균강우량을 비교하였고, 유역면적 등에 따른 면적평균강우량의 변화특성을 분석 하였다.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.8 no.4
• /
• pp.209-221
• /
• 2006

The purpose of this study is to analyze the effects of climate change on the nonpoint source pollution in a small watershed using a mid-range model. The study area is a basin in a rural area that covers 384 ha with a composition of 50% forest and 19% paddy. The hydrologic and water quality data were monitored from 1996 to 2004, and the feasibility of the GWLF (Generalized Watershed Loading function) model was examined in the agricultural small watershed using the data obtained from the study area. As one of the studies on climate change, KEI (Korea Environment Institute) has presented the monthly variation ratio of rainfall in Korea based on the climate change scenario for rainfall and temperature. These values and observed daily rainfall data of forty-one years from 1964 to 2004 in Suwon were used to generate daily weather data using the stochastic weather generator model (WGEN). Stream runoff was calibrated by the data of $1996{\sim}1999$ and was verified in $2002{\sim}2004$. The results were determination coeff, ($R^2$) of $0.70{\sim}0.91$ and root mean square error (RMSE) of $2.11{\sim}5.71$. Water quality simulation for SS, TN and TP showed $R^2$ values of 0.58, 0.47 and 0.62, respectively, The results for the impact of climate change on nonpoint source pollution show that if the factors of watershed are maintained as in the present circumstances, pollutant TN loads and TP would be expected to increase remarkably for the rainy season in the next fifty years.

• Korean Journal of Remote Sensing
• /
• v.33 no.2
• /
• pp.201-211
• /
• 2017

The estuary in Nakdong River has changes by the construction of harbors, land reclamation and artificial waterway changes. These resultslead to changes of extinction and creation of deltaic barrier island. The deltaic barrier island changes in the Nakdong River estuary affect the function of the barrier islands and cause environmental changes. Therefore, it is important to monitor the changes in the area of the Nakdong estuary. In this study, long-term changes of the area and suspended sediment of deltaic barrier island in the Nakdong River estuary were analyzed using Landsat TM/ETM+ images. As a result, end point rate (EPR) values of shoreline in Jinwoodo and Sinjado are about 5m/yr and about 50 m/yr, respectively. The EPR values of north-south and east-west direction in Doyodeung are 20 m/yr and -20 ~ 10 m/yr. The suspended sediment concentration (SSC) has a maximum value of $25g/m^3$ in the vicinity of Jinwoodo and Sinjado, while it has a maximum concentration of $40g/m^3$ in the vicinity of Shinjido and Doyodeung. In other words, the area and the SSC change are small in Jinwoodo, and the area change and the SSC variation are large in Sinjado and Doyodeung. As a result of analysis of correlation between area change and SSC variation using all data, the Pearson coefficient value (r) is 0.36 and it is 0.32 in winter data. In other words, it is considered that the SSC variation affectsthe deltatic barrier island area change. However, verification using advanced altimetry data is necessary in the future. These studies can be used for coastal monitoring and environmental monitoring.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.2
• /
• pp.101-109
• /
• 2013

Recently, it is certain that the increase of heating and cooling energy consumption by radical change in climate condition has caused serious problems related to environmental and energy concerns associated with increase of fossil fuel usage and carbon dioxide production as well as global warming. So, various actions to reduce greenhouse gas exhaustion and energy consumption have been prepared by world developed countries. Our government has also been trying to seek energy control methods for houses and buildings by proclaiming political polices on low-carbon green growth and construction and performance standards for environment-friendly housing. The energy consumption by buildings approximately reaches 25% of total korea energy consumption, and the increasing rate of energy consumption by buildings is stiffer than the rate by the other industries. The greatest part in the buildings of the energy consumption is building facade. While lots of research projects for reducing energy consumption of the facade have been conducted, but a few research projects on concrete comprising more than 70% of outsider of buildings has been tried. This research presents here a study to improve the insulation property of structural concrete formed by micro form admixture (MFA) with experimentally reviewing the physical, mechanical and thermal characteristics of the concrete. As the results of this experiment, in the case of concrete mixed with MFA, slump loss has been improved. As the mixing ratio of MFA increases, the compressive strength is decreased and thermal conductivity is increased. Also it was found that water-cement ratio increases, the compressive strength is decreased and thermal conductivity is increased. but, there was not big influence by the change of fine aggregate ratio.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.120-120
• /
• 2010

에너지 절약적 차원에서 한 대의 실외기에 다수의 실내기가 접속되는 개별공조형 멀티 열펌프에 관한 연구 및 개발과 보급이 증대되고 있다. 본 연구에서는 복수의 실내기를 갖고 가변속 압축기를 채용한 지열원 물대공기 멀티열펌프시스템을 학교 현장에 설치하여 제조사의 운전 제어 알고리즘에 따라 일일 냉난방 실증 성능 특성을 분석하였다. 2008년 9월 30일의 냉방부하가 낮은 일자에 대하여 시간에 따른 부하 변동에 따라 압축기의 용량가변으로 실내기 냉방용량은 정격용량 대비 17.1%에서 111.3%의 범위에서 변이되었으나, 열펌프 유닛의 일일 최대 COP는 6.2를 나타냈으며, 일일 평균 열펌프 유닛 COP는 4.5로 열펌프 유닛 인증 기준 이상의 성능을 나타냈다. 2008년 11월 10일 대비 2008년 12월 15일에는 시스템 가동 중의 평균 외기온도가 $9.6^{\circ}C$ 감소하였으나, 각 재실공간의 용도별 부분 부하특성으로 11월 10일 보다 난방 부하량이 작게 나타났다. 하지만, 12월 15일에는 부하량이 매우 작아서 11월 10일보다 잦은 압축기 가변에 따른 손실로 일일 평균 COP가 낮게 나타났다. 2009년 1월 12일에는 정격 용량대비 94%의 부하율로 11월 10일과 12월 15일 대비 4배 이상의 부하량으로 압축기 용량 가변율이 작아서 난방용량과 COP 변화율이 작게 나타났다. 2009년 1월 12일에는 지중순환수의 실외열교환기 유입온도가 2008년 12월 15일보다 감소하고, 시스템의 난방용량 증가로 상대적으로 응축기와 증발기 크기가 감소한 효과로 히트펌프 유닛 COP가 감소하였으나, 본 지열원 열펌프 제조사에서 생산하고 있는 본 지열원 시스템과 동일한 압축기 등을 채용한 동일 용량의 공기열원 열펌프의 1월 12일 외기온도 $-10^{\circ}C$에서의 열펌프 유닛 COP 대비 70% 우수한 성능을 나타냈다. 본 지열원 히트펌프의 2008년 11월 10일의 일일 평균 히트펌프 유닛 COP는 외기온도가 낮고 일일 부하량이 크게 나타난 1월 12일의 일일 평균 히트펌프 유닛 COP 대비 37% 높게 나타났으나, 지중순환펌프의 정속운전으로 시스템 요구 지중순환수 유량 증가에 따른 성능 향상보다 소비전력 증가 영향이 커서 1월 12일의 시스템 COP 보다 33.3% 작은 값을 나타냈다. 본 연구의 용량 가변형 압축기를 채용한 지열원 멀티 히트펌프 유닛을 지열원 냉난방 시스템의 히트펌프 유닛으로 사용할 경우 시스템 최적화를 통한 시스템 COP 향상과 연간에너지 절감을 이루기 위해서는 히트펌프의 용량 변화 시에 지중순환펌프의 순환 유량 최적화를 위한 효율적 운전 제어 알고리즘 개발이 요구된다.

• Journal of Korean Library and Information Science Society
• /
• v.50 no.1
• /
• pp.293-312
• /
• 2019

The purpose of this study is to find ways to improve the evaluation system of school library operation whose participation rate is getting lower. We conducted analyzing the current status of operating evaluation of school libraries through literature search. In doing so, questionnaire method was conducted to inquire the recognition of the 205 staff members of school libraries. The outcome of the survey shows that the participation rate of operating evaluation of school libraries decreased from 22.2% in 2009 to 7.2% in 2017. The validity of the quantitative evaluation method was significantly low at 2.84 and the validity of the qualitative evaluation method was 2.97. The average score of the validity index for 'Establishing the annual operation plan' was the highest at 3.90, and that of 'Community service' was the lowest at 2.27. The biggest reason for not participating in the evaluation was due to the staff's high workload. There is a need to seek ways to improve the evaluation index and ways to participate since the result shows very low awareness of the school library evaluation. Through this study, it is expected that the school library evaluation will become the foundation for effective revitalization of school library operation.

• Membrane Journal
• /
• v.29 no.6
• /
• pp.314-322
• /
• 2019

A worsened drought in Chungnam province of Korea due to climate change and increasing water demand at Daesan industrial complex have motivated the 100,000 ㎥/d seawater desalination project. In this study, therefore, the comprehensive analysis of parameters affecting the reverse osmosis (RO) performance was conducted. Under the various conditions of feedwater salinity and temperature in Daesan, energy consumption was calculated as 2.39 ± 0.13 kWh/㎥. The decrease in membrane flux and recovery rate positively impacted annual operation cost. The average total dissolved solids (TDS) of the permeate and energy consumption with highly permeable membrane according to the membrane manufacturer were 3.84 mg/L and 2.22 ± 0.13 kWh/㎥, respectively. In addition, energy saving up to 0.29 kWh/㎥ or cost reduction of membrane module up to 15.6% is expected by changing the RO configuration from full two pass to partial or split partial two pass.

• Journal of Korea Water Resources Association
• /
• v.52 no.11
• /
• pp.941-946
• /
• 2019

A wildfire could significantly alter the local hydrological regime, depending on the area and severity, and thus it is critical to understand its effect and feedback using data and simulation. For the wildfire in Gangwon-do on April 4-5, 2019, South Korea, we retrieved the Normalized-Burned Ratio (NBR) index using remote-sensing data (500-m 8-day MODIS surface reflectance data), and detect the damaged-area based on the difference in the NBR (dNBR) before and after the fire. The damaged area was $29.50km^2$ in total, taking up 1.00-6.19% of five catchments. We then used remote-sensing data (500-m 8-day MODIS evapotranspiration data) and estimated that annual evapotranspiration (AET) would decrease as 0.05-1.56% over the five catchments, as compared to the pre-fire AET (2004-2018). This study highlights the importance of improving our understanding about the impact of wildfire on the local hydrological cycle.