• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.148-148
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• 2023

산업 고도화로 인하여 복잡하고 다양한 유기물의 사용량이 증가하였으며, 공공수역 내 새로운 오염물질이 유입됨에 따라 생화학적 산소요구량(BOD) 중심의 수질평가에 한계를 나타내었다. 이후 난분해성 물질을 고려한 유기물관리 정책과 총량관리의 필요성이 제기되었고 국내 하천과 호소에서는 총 유기탄소(TOC)를 유기물 관리지표로 설정하였다. 그러나 부영양 하천과 호소에서 TOC는 외부 부하뿐만아니라 식물플랑크톤의 과잉성장에 의해 증가할 수 있는 항목이므로 TOC 관리정책 추진을 위해서는 유기물의 기원에 대한 파악이 필요하다. 한편, 우리나라와 같이 몬순 기후대에 속한 댐 저수지의 경우 강우시 유입하는 탁수에 의해 다량의 유기물과 인이 유입되기도 하지만 식물플랑크톤의 제한요인 중 광량에 많은 영향을 미친다. 식물플랑크톤의 광합성은 수체 내 유기탄소 내부생성에 매우 중요한 요소이나 점 단위의 실험적 방법을 활용한 유기탄소 순환 해석은 저수지의 시·공간적인 변동성을 고려하기에 한계가 있다. 본 연구의 목적은 금강 수계 최대 상수원인 대청호를 대상으로 3차원 수리-수질 모델을 적용하여 유기탄소 성분 별 유입과 유출, 내부생성 및 소멸량을 평가하고 탁수가 저수지에서의 유기탄소 순환에 미치는 영향을 분석하는데 있다. 유기탄소 물질수지 해석을 위해 AEM3D 모델을 사용하였으며 2018년을 대상으로 입력자료를 구축한 후 보정 및 검정을 수행하였다. 모델은 유기탄소를 입자성, 용존성, 그리고 난분해성과 생분해성으로 구분하여 모의하며 유기물질 성상별 실험결과를 이용하여 입력자료를 구축하였으며 유기탄소순환 해석을 위해 4가지의 탄소성분과 조류 세포 내 탄소의 질량 변화율을 계산하였다. 이를 위해 외부 유입·유출부하율, 수체 내 생성(일차생산, 재부상, 퇴적물과 수체 간 확산) 및 소멸률(POC 및 조류 침강, DOC 무기화, 탈질)을 고려하였으며 탁수의 영향을 분석하기 위해 탁수 포함여부 시나리오를 구성하고 유기탄소 생성 및 소멸기작별 변동성을 비교 분석하였다. 모델은 2018년의 물수지를 적절히 재현하였으며 저수지의 수온 및 탁도 성층구조를 잘 재현해내면서 전반적인 수질을 적절하게 모의하였다. 탁수를 고려하였을 시 연간 TOC 부하량 중 내부기원 부하량은 56% 수준이였으나 탁수를 배제한 경우 내부기원 부하량은 82%로 나타났다. 특히, 연평균 Chl-a 농도가 44~48% 차이가 발생하면서 1차생산량이 약 4배가량 증가하였다. 몬순지역에서의 탁수는 체류시간이 긴 성층 저수지에서 식물플랑크톤 성장제어에 큰 영향을 미쳤으며 전반적인 유기탄소 순환을 해석하는데 있어 매우 중요한 인자로 작용하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.62-62
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• 2021

산업 고도화로 인하여 복잡하고 다양한 유기물의 사용량이 증가하였으며, 공공수역 내 새로운 오염물질이 유입됨에 따라 생화학적 산소요구량(BOD) 중심의 수질평가에 한계를 나타내었다. 이후 난분해성 물질을 고려한 유기물관리 정책과 총량관리의 필요성이 제기되었고 국내 하천과 호소에서는 총 유기탄소(TOC)를 유기물 관리지표로 설정하였다. 그러나 부영양 하천과 호소에서 TOC는 외부 부하뿐만아니라 식물플랑크톤의 과잉성장에 의해 증가할 수 있는 항목이므로 TOC 관리정책 추진을 위해서는 유기물의 기원에 대한 파악이 필요하다. 특히, 국내 하천에서 나타나고 있는 난분해성 유기물 오염도의 증가 추세에 대응한 실효성 있는 유기물 오염관리 정책을 수립하기 위해서는 다양한 유기물의 근원을 정확하게 파악하는 것이 매우 중요하다. 본 연구의 목적은 금강 수계 최대 상수원인 대청호를 대상으로 3차원 수리-수질 모델을 적용하여 유기탄소 성분 별 유입과 유출, 내부생성 및 소멸량을 평가하고 저수지시스템에서의 유기탄소 물질수지를 해석하는 데 있다. 유기탄소 물질수지 해석을 위해 AEM3D 모델을 사용하였으며 2017년을 대상으로 입력자료를 구축한 후 보정을 수행하였고 2018년을 대상으로 모델을 검정하였다. 모델은 유기탄소를 입자성, 용존성, 그리고 난분해성과 생분해성으로 구분하여 모의하며 유기물질 성상별 실험결과를 이용하여 입력자료를 구축하였다. 유기탄소 물질수지 해석을 위해 4가지의 탄소성분과 조류 세포 내 탄소의 질량 변화율을 계산하였다. 이를 위해 외부 유입·유출부하율, 수체 내 생성(일차생산, 재부상, 퇴적물과 수체 간 확산) 및 소멸률(POC 및 조류 침강, DOC 무기화, 탈질)을 고려하였다. 모델은 2017년과 2018년의 물수지를 적절히 재현하였으며 저수지의 성층구조를 잘 재현해내면서 전반적인 수온, 수질을 적절하게 모의하였다. 연간 TOC 부하량 중 내부기원 부하량은 2017년 68.4 %, 2018년은 높은 강우량의 영향으로 55.0%로 산정되었다. 내부 소멸 기작 중 침전으로 인한 손실이 가장 높은 것으로 나타났으며, 2017년과 2018년 각각 31.3%, 29.0%로 나타났다. TOC의 공간분포는 Chl-a 농도 분포와 유사하게 나타났으며, 댐 설치로 형성된 정체수역은 유역의 유기물 순환에 많은 영향을 미치는 것으로 평가되었다. TOC 관리 정책 기초자료 확보를 위해서는 향후 유역-저수지 시스템을 연계한 유기물 물질순환 심층 연구가 필요하다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.208-220
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• 2019

The seasonality of leaf fall has important implications for understanding the response of trees' phenology to climate change. In this study, we quantified the leaf fall pattern with a model to estimate the timing and speed of leaf litter according to species and considered the nutrient use strategy of canopy species. In the autumns of 2015 and 2016, leaf litter was collected periodically using 36 litter-traps from the deciduous forests in Gwangneung and sorted by species. The seasonal leaf fall pattern was estimated using the non-linear regression model of Dixon. Additionally, the resorption rate was calculated by analyzing the nitrogen concentration of the leaf litter at each collection time. The leaf litter generally began in early October and ended in mid-November depending on the species. At the peak time (T50) of leaf fall, on average, Carpinus laxiflora was first, and Quercus serrata was last. The rate of leaf fall was fastest (18.6 days) for Sorbus alnifolia in 2016 and slowest (40.8 days) for C. cordata in 2015. The nitrogen resorption rates at T50 were 0.45% for Q. serrata and 0.48% for C. laxiflora, and the resorption rate in 2015 with less precipitation was higher than in 2016. Since falling of leaf litter is affected by environmental factors such as temperature, precipitation, photoperiod, and $CO_2$ during the period attached foliage, the leaf fall pattern and nitrogen resorption differed year by year depending on the species. If we quantify the fall phenomena of deciduous trees and analyze them according to various conditions, we can predict whether the changes in leaf fall timing and speed due to climate change will prolong or shorten the growth period of trees. In addition, it may be possible to consider how this affects their nutrient use strategy.

• Journal of Climate Change Research
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• v.1 no.3
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• pp.205-210
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• 2010

LED light has various advantages such as an energy saving effect of over 80% compared to existing lighting and environmentally friendly characteristics; however, there has been no affordable market for LED lighting because of its expensive price. This study discussed the validity of the expansion of distribution of LED lighting through an assessment of economic efficiency concerning LED lightening in order to analyze its efficiency in terms of energy savings and maintenance and repair, which will be generated as a result of the change from existing incandescent bulbs to LED lighting in the public sector. As to the target of analysis, the paper reviewed the validity of change to LED lighting as a result of the elimination of existing incandescent bulbs, by referring to 'the current incandescent bulb use and elimination performance' published by the Ministry of Knowledge Economy based on the "Elimination management system" executed by Korea Energy Management Corporation. The paper considered expenses for change, annual power savings amount and electric charges savings amount, repair and maintenance cost, $CO_2$ reduction volume, and the profit from the sale of CER (certified emission reduction). As a result of analyzing economic efficiency, when the discount rate during the change of existing incandescent bulb lighting to LED lighting is 3.26%, the profit was 8,648,400,000 won. Accordingly, NPV was analyzed to have a 'positive (+)' value, which means that this change is profitable.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.579-596
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• 1997

A simulation study was carried out to delineate potential effects of the lake-induced climate change on crop productivity around Lake Imha which was formed after a multi-purpose dam construction in Andong, Korea. Twenty seven cropping zones were identified within the 30 km by 25 km study area. Five automated weather stations were installed within the study area and operated for five years after the lake formation. A geostatistical method was used to calculate the monthly climatological normals of daily maximum and minimum temperature, solar radiation and precipitation for each cropping zone before and after the dam construction. Daily weather data sets for 30 years were generated for each cropping zone from the monthly normals data representing "No lake" and "After lake" climatic scenarios, respectively. They were fed into crop models (ORYZA1 for rice, SOYGRO for soybean, CERES-maize for corn) to simulate the yield potential of each cropping zone. Calculated daily maximum temperature was higher after the dam construction for the period of October through March and lower for the remaining months except June and July. Decrease in daily minimum temperature was predicted for the period of April through August. Monthly total radiation was predicted to decrease after the lake formation in all the months except February, June, and September and the largest drop was found in winter. But there was no consistent pattern in precipitation change. According to the model calculation, the number of cropping zones which showed a decreased yield potential was 2 for soybean and 6 for corn out of 27 zones with a 10 to 17% yield drop. Little change in yield potential was found at most cropping zones in the case of paddy rice, but interannual variation was predicted to increase after the lake formation. the lake formation.

• Childhood Kidney Diseases
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• v.5 no.2
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• pp.117-124
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• 2001

Purpose : Since Mendoza(1990)'s report that long term methylprednisolone pulse therapy by Mendoza protocol (MP therapy) is a good treatment option in focal segmental glomerulosclerosis(FSGS), there have been reports of the effects of this therapy in steroid-resistant nephrotic syndrome. However, no studies have been performed on the effects of MP therapy in steroid- dependent nephrotic syndrome and secondary nephrotic syndrome. In this study, we investigated the effects of long term MP therapy in primary and secondary nephrotic syndrome in which previous treatment options were not effective. Methods : We chose 10 children who were diagnosed with steroid-dependent minimal change nephrotic syndrome(SD-MCNS), who had shown frequent relapse during the immunocompromised or cytotoxic therapy Period, and 6 children with FSGS and 5 children with secondary nephrotic syndrome children, who had shown no response during the previous therapy period. We treated these patients according to Mendoza protocol involving infusions of high doses of methylprednisolone, often in combination with oral cyclophosphamide for 82 weeks. Results : In all the 10 children with SD-MCNS, complete remission was visible on average of $18{\pm}9$ days after MP therapy was started. However, all these children relapsed during or after MP therapy. In these children, the mean relapse rate prior to MP therapy was $2.1{\pm}1.0$ relpases/year, which was reduced to $1.4{\pm}0.9$ relapses/year during MP therapy(P>0.05) and rose to $2.7{\pm}1.0$ relapse/year after MP therapy. Of the 6 children with FSGS, 4 children($67\%$) showed complete remission, of whom 3 children($50\%$) remained in the remission status during the follow up period, $1.2{\pm}0.7$ years, after the end of MP therapy. 2 children($33\%$) showed no response. All of the 5 children with secondary nephrotic syndrome showed remission and remained in the remissiom status during the follow up period, $1.7{\pm}0.6$ years The only side effect of MP therapy was transient hypertension in 10 children of ail subjects during the intravenous infusion of methylprednisolone. Conclusion : We conclude that although long term MP therapy is not effective in the treatment of SD-MCNS, it is an effective therapy against intractable FSGS and secondary nephrotic syndrome. (J Korean Soc Pediatr Nephrol 2001 ; 5 : 117-24)

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.275-283
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• 2016

The objective of this study was to examine carbon dynamics with biomass, soil $CO_2$ efflux, litter and root decomposition after tree density control in young Pinus densiflora stands. The stands were established with 50% thinning, clear-cut, and control stands with three pseudo-replicated plots and a bare soil plot in 8-year-old Pinus densiflora nursery field. Monthly measurements were conducted from March 2012 to February 2014 and aboveground biomass and coarse-roots were estimated by derived allometric equations. Average diameter growth at root collar in control and thinned was 0.89 cm and 1.48 cm per year, respectively, and the diameter growth of control stand was significantly higher than that of thinned stands (p<0.05). Total biomass was estimated to 5.17, $4.85kg\;C\;m^{-2}$ per year in control and thinned, respectively. Annual soil $CO_2$ efflux in control, thinned, clear cut, and bare soil was 3.71, 3.90, 4.17, $4.56kg\;CO_2\;m^{-2}\;yr^{-1}$, respectively and removing trees significantly increased soil $CO_2$ efflux (p<0.05). Net Ecosystem Production (NEP) was 1.57, 1.36, -0.67, $-1.25kg\;C\;m^{-2}\;yr^{-1}$ in control, thinned, clear cut and bare soil in the young Pinus densiflora stands. NEP was significantly decreased by removing trees. Thinning increased diameter at root collar and carbon of individual tree and recovered 86% of carbon removed by thinning after one-year. In addition, soil $CO_2$ efflux increased and NEP increased by thinning. Results of this study, tree density control such as thinning increased the carbon storage and growth of the young Pinus densiflora stands.

• Food Science and Preservation
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• v.9 no.3
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• pp.271-276
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• 2002

To develop a wrapping film, which suppresses the microbial decay through the storage and prolongs the selflife of fruits and vegetables, the antimicrobial packaging films were prepared and applied to the preservation of strtwberries and cucumbers. Low density polyethylene(LDPE) film of 50㎛ thickness was faricated with 1% of Scutellariae baicalensis extract. The LDPE film impregnated with Scutellariae baicalensis extract showed antimicrobial activity on the disk test against Bacillus cereus, Escherchia coli and Fusarium sp.. The antimicrobial film changed the color and light transmittance, but did not affect heat shrinkage, mechanical tensile strength and wattability. Strawberries and cucumbers were separately wrapped with packaging films in the state of closely-adhered packaging as well as modified atmosphere packaging(MAP). The wrapped strawberries and cucumbers were stored for 21 days at 5$\^{C}$ and for 40 days at l0$\^{C}$, respectively. For the packaged strawberries and cucumbers at 5$\^{C}$ and 10$\^{C}$, the LDPE film impregnated with Scutellariae baicalensis extract showed the reduced growth of total aerobic bacteria, molds and yeasts and did not give any negative effect on other quality attributes during storage in comparison with conttrol film without any additive.

• The Korean Journal of Financial Management
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• v.20 no.1
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• pp.93-124
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• 2003

This paper studies the financial analyst's forecasting activities on the firm's operating performance during the period from 1999 to 2003. In this study, financial analyst's forecasting activities are focused on the sales, operating income and net income and financial analyst's forecasting accuracy, forecasting revising patterns and forecasting activities to the unexpected firm's operating performance are studied. Some empirical findings in this study are as follows. First, standard estimate error on the sales, operating income and net income are all significantly negative value and so financial analyst's forecast on the firm's operating performance are upwardly biased. Second, domestic financial analyst's forecasting activities is relatively more accuracy than foreign financial analyst's forecasting activities. Third, forecasting time is more close to the end of the operating performance announcement day, forecasting activities are more accuracy. Fourth, comparing with individual financial analyst's forecast, consensus forecast is more accuracy. Fifth, in the comparative forecasting activities study according to the prior firm's operating performance, financial analyst's forecasting revision activities are found to be upward or downward. Sixth, financial analysts overreact in the sales forecast and underreact in the operating income and net income forecast. Seventh, in the empirical analysis on the Easterwood-Nutt's test model(1999) which the firm's performance change are divided into the expected performance change and the unexpected performance change, it is found that financial analyst's forecasting activities on the firm's operating performance are systematically optimistic.

• Journal of Korean Society of Forest Science
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• v.79 no.4
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• pp.388-397
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• 1990

This study was conducted to investigate the changes of land use and stand volume around Mt. Kuem-O by B/W aerial photographs in 1979 and B/W Infrared aerial photographs in 1988. The results obtained in this study were as follow : 1. In classification of forest type on aerial photographs, coniferous stand was dark tone and hardwood stand was light tone and irregularly rounded crowns. 2. In classification of coniferous stand, Pinus densiflora was narraw cone and rounded tip of crowns and rough texture, Pinus rigida was irregulary rounded and broadly conical crowns. 3. To refer to changes of forest land area, mixed forest was changed into P. desiflora (687ha), P. rigida (130ha) and hardwood stand (219ha). 4. The regression equations between crown diameter and DBH were significant at 1% level by F-test in all stands. So the equation, D=a+bCD was used to estimate DBH. 5. The tree height curve equations were significant at 1% level by F-test in all stands. To estimate tree height the equation, logH=loga+blogD was adopted in P. densiflora and L. leptolepis and $H=a-bD+cD^2$ was adopted in P. rigida, hardwood stand and mixed forest. 6. The highest volume per hectare was observed in L. leptolepis and mixed forest showed the greatest growth percentage, while the lowest volume per hectare and growth percentage were observed in hardwood stand.