• 한국물환경학회지
• /
• 제28권1호
• /
• pp.10-17
• /
• 2012

The middle and lower reaches of the Kum River system become stagnant in dry seasons with florishing of phytoplankton. In this study primary productivity of phytoplankton were measured by the C-14 uptake method and the P-I model method at seven main stream sites of the Kum River from the Daechung Dam outet to the river mouth. Nutrients (TN, TP, DIP, TIN) concentrations were measured in the mainstream and tributaries and compared with the variation of assimilation number. The range of primary productivity was $40{\sim}4,558mgC{\cdot}m^{-2}{\cdot}day^{-1}$ and it was higher than those of lentic ecosystems in Korea. Average TN and TP were $4.1mgN{\cdot}L^{-1}$, $70.6mgP{\cdot}m^{-3}$, respectively. Tributaries showed higher nutrient concentrations than the main stream. After two major tributaries merged with the discharging water of the Daechung Dam phyotplankton biomass and productivity increased drastically and remained at the similar eutrophic level through the downstream reach to the river mouth. Both dissolved phosphorus and nitrogen concentrations showed positive correlation with assimilation number of phytoplankton. In conclusion phytoplankton productivity is at the level of eutrophic water and it was higher than usual lentic habitats. Nutrient concentrations are critical factors in controlling productivity in the lower reach of the Kum River.

• 한국재난정보학회 논문집
• /
• 제8권3호
• /
• pp.242-257
• /
• 2012

우리나라의 인구변화의 양상은 사망률의 감소, 평균수명의 연장으로 고령화, 여성화 추세이며, 더불어 출산율의 저화와 고령화 인구의 비율이 더욱 증가되고 있다. 어려운 인력수급으로 건설노무자는 외국인에 의해 충원되고 있으며 미국, 유럽, 중국 등과 FTA의 체결로 노동집약적 산업이 쇠퇴하면 건설노무자의 일자리는 지속적으로 줄어들게 된다. 이것은 건설 기능인력의 부족현상과 기능 인력의 노무비 증가로 국가의 경제적 사회적 환경에 중대한 영향을 주어 건설업 생산성 저하의 주요 요인이 되고 있다. 따라서 이 연구는 건설업 생산성을 위해 최근 자료로부터 국내 건설경기 동향, 산업별 생산성 지수, 산업별 취업자 추이, 연령 계층별 기능인력 추이, 여성 기능 인력 추이, 노동시간 추이, 외국노동자 인력 추이, 건설업의 수주동향 분석, 업체규모별 수주동향, 건설경영분석지표로부터 노동생산성에 관한 종업원 1인당 부가가치 분석으로 건설업생산성 발전전망을 제시하였다.

• 보건행정학회지
• /
• 제23권1호
• /
• pp.78-89
• /
• 2013

This study empirically analyze efficiency and productivity changes of public hospitals of Korea using data envelopment analysis/Window model and global Malmquist indices model. We use the ten-year data from 2001 to 2010 of 30 regional public hospitals listed database from the Association of Korean Regional Public Hospitals. The main focuses are to reveal whether the technical inefficiency are improved as time goes by, and efficiency and productivity are affected by environmental factors. The results can be summarized as follows. First, the efficiencies of public hospitals rise in trend as time passes. Second, regional public hospitals show the different average efficiencies according to their regional type, hospital type, operational type, medicaid type, and demand and supply conditions by Mann-Whitney U-tests. Third, technical efficiency changes mainly contribute to 4.4% annual average growth rate of productivity of regional public hospitals during that period. Our findings have some policy implications. It is confirmed that there exist some environmental inefficiencies, and those inefficiencies can not be overcome through just improving the inner management system. Thus, policy and institutional changes are necessary for regional public hospitals to improve efficiency and productivity overall.

• 문화기술의 융합
• /
• 제7권4호
• /
• pp.785-789
• /
• 2021

파프리카 생산성은 동일한 품질 온실, 지역 간에 차이를 나타내고 있다. 이러한 차이는 다양한 환경요인의 차이에서 오는 것으로 알려져 있다. 본 연구는 동일 지역에서 동일 품질 온실 중에서 생산성이 높거나(HPF) 낮은(LPF) 온실 간 내부 환경요인의 수준 차이를 알아보고자 수행되었다. 주요 환경요인들의 일 또는 주의 평균값에서 두 온실 간에 가장 큰 차이를 보인 것은 CO₂ 농도였지만, LPF에서 HPF보다 매우 높아 생산성 차이 요인으로 판정하기 않았다. 14개 환경 요인들 간 상관분석에서 광량과 수분 관련 요인들 간에 상관성을 나타내었다. 증산량에 관련된 수증기압포차와 상대습도 간 선형회귀모형의 회귀계수는 HPF에서 -0.0202kpa, LPF에서는 -0.0262kpa로 나타났다. 특히 2월과 3월에는 LPF에서 VPD가 1.5kpa 이상이었고, 재배 초기에 누적 광량 대비 누적 수증기압포차의 급격한 증가가 나타났다. 따라서 LPF에서 생산성이 낮은 원인은 재배 초기와 겨울철에 적은 광량 조건에서 높은 VPD에 의한 높은 증산량이 식물체에게 수분 스트레스를 주었기 때문으로 판단된다.

• 대한산업공학회지
• /
• 제37권4호
• /
• pp.350-357
• /
• 2011

In the recent, it is gradually important for airport to consider environmental aspects as sustainable development is emerged. ICAO, FAA and individual countries has tried to reduce airport noise and pollution. Thus, the effort is needed to incorporate environmental factor into productivity indicator of airport. Our paper use DEA method with the non-parametric directional output distance function(DDF) to assess productivity of 14 airports in Korea during 2008~2010. In addition to three inputs, two conventional outputs, two undesirable outputs have been considered : noise and air pollution. Results are compared from models that do not include undesirable outputs. Inclusion in the analysis of the undesirable effects of airport operations leads to greater and closer airport's efficiency scores.

• Journal of Applied Biological Chemistry
• /
• 제62권1호
• /
• pp.67-71
• /
• 2019

All countries, including Korea, are currently experiencing the effect of rapid climate change. As a result, the cultivation area of many crops including wheat is changing, or productivity is falling sharply. If enough nitrogen is present in the soil, the increase in atmospheric carbon dioxide due to the greenhouse effect can lead to increased photosynthesis of plants, resulting in increased productivity. By contrast, a low proportion of nitrogen in soil does not increase production, often leading to the use of nitrogen fertilizers to increase crop productivity: this causes serious environmental pollution due to the leakage of nitrogen fertilizers used by crops. Increasing the understanding of the molecular level of the plant nitrogen use efficiency mechanism may contribute to increased productivity of crops and reduced of environmental pollution by nitrogen. In Korea, cultivars have developed 35 kinds of wheat, such as 'keumgang' and 'Chokyeong', which can be used for specific purposes such as baking or noodles. In this study we investigate 'keumgang' and 'Chokyeong' in order to elucidate the mechanism of nitrogen use ability of wheat and contribute to the reduction of environmental pollution by providing guidelines for the proper use of nitrogenous fertilizer.

• Animal Bioscience
• /
• 제36권2호
• /
• pp.248-255
• /
• 2023

Objective: Stress factors such as high temperatures, overcrowding, and diurnal temperature range exert profound negative effects on weight gain and productivity of broiler chickens. The potential of gamma aminobutyric acid (GABA) as an excitatory neurotransmitter was evaluated under various stress conditions in this study. Methods: The experiment was conducted under four different environmental conditions: normal, high temperature, overcrowded, and in an overcrowded-diurnal temperature range. The experimental groups were divided into (-) control group without stress, (+) control group with stress, and G50 group (GABA 50 mg/kg) with stress. Weight gain, feed intake, and feed conversion ratio were measured, and stress reduction was evaluated through hematologic analysis. Results: The effects of GABA on broilers in four experimental treatments were evaluated. GABA treated responded to environmental stress and improved productivity in all the experimental treatments. The magnitude of stress observed was highest at high temperature, followed by the overcrowded environment, and was least for the overcrowded-diurnal temperature range. Conclusion: Various stress factors in livestock rearing environment can reduce productivity and increase disease incidence and mortality rate. To address these challenges, GABA, an inhibitory neurotransmitter, was shown to reduce stress caused due to various environmental conditions and improve productivity.

• Environmental Engineering Research
• /
• 제25권2호
• /
• pp.135-146
• /
• 2020

This study was aimed to investigate the possibility of using raw and anaerobically-digested piggery wastewater as culture media for a green microalga Chlorella vulgaris (C. vulgaris). Due to high concentration of ammonia and dark color, the microalga did not grow well in this wastewater. In order to solve this problem, air stripping and NaOCl-treatment were applied to reduce the concentration of NH₃-N and the color intensity from the wastewater. Algal growth was monitored in terms of specific growth rate, biomass productivity, and nutrient removal efficiency. As a result, C. vulgaris grew without any sign of inhibition in air-stripped and 10-folds diluted anaerobically-digested piggery wastewater with enhanced biomass productivity of 0.57 g/L·d and nutrient removal of 98.7-99.8% for NH₃-N and 41.0-62.5% for total phosphorus. However, NaOCl-treatment showed no significant effect on growth of C. vulgaris, although dark color was removed greatly. Interestingly, despite that the soluble organic concentration after air stripping was still high, the biomass productivity was 4.4 times higher than BG-11. Moreover, air stripping was identically effective for raw piggery wastewater as for anaerobic digestate. Therefore, it was concluded that air stripping was a very effective method for culturing microalgae and removing nutrients from raw and anaerobically-digested piggery wastewaters.

• Journal of Forest and Environmental Science
• /
• 제32권2호
• /
• pp.189-195
• /
• 2016

Logging equipment and method have a major influence on harvesting productivity and cost. This study investigated the productivity and operational costs of tree-length cable yarding system using HAM300, a domestically developed tower yarder. We tested HAM300 for thinning operation in Pinus densiflora stands at Gangreung, Gangwon-do on April, 2014. To assess the productivity we conducted time study for each stage of the operation. When the average time/cycle was examined for each stage of the operation, the longest was for yarding (241 sec), followed by delimbing (237 sec), felling (153 sec), and processing (103 sec). Furthermore, productivity for felling was $8.6m^3/hr$, followed by delimbing ($5.1m^3/hr$), yarding ($3.5m^3/hr$), and processing ($8.1m^3/hr$). The total cost for the tree-length logging system was $58,446won/m^3$, of which the majority was incurred by the yarding cost at $46,217won/m^3$ (79.3%), whereas the lowest cost was for felling at $2,359won/m^3$ (4.1%). We suggest that it is necessary to foster specialized operators and provide training in operating the tower yarder thereby implementing efficient harvesting system resulting from low-cost yarding.

• KSBB Journal
• /
• 제19권6호
• /
• pp.478-483
• /
• 2004

본 연구를 통하여 유기산 생산을 위한 본 연구를 통하여 유기산 생산을 위한 Propionibacterium acidipropionici의 발효 특성을 규명하여 보았다. P. acidipropionici ATCC 25562, 4875, 및 4965 등 세 균주를 선별하여 발효 실험에 의한 최적 성장조건을 규명한 결과, peptone $1.5\%$ (w/v), yeast extract $0.75\%$ (w/v)에서 유기산 생산성이 최대로 나타났다. 또한 주어진 영양 조건에서 온도, pH 등 환경을 제어하며 회분식 발효를 실시한 결과 세 균주 모두 pH 6.0에서 유기산 수율과 생산성이 가장 높았으며, 그 중에서도 P acidipropionci ATCC 4965 균주가 유기산 생산성이 0.29 g total acids/L/h로 가장 우수한 것으로 판명 되었다. 세 균주의 화학양론적인 유기산 생산비를 비교해본 결과 1.5몰의 글루코오스로부터 $1.60{\sim}2.34$몰의 프로피온산과 $0.74{\sim}1.05$몰의 초산을 생산하는 것으로 나타났다.