• 한국환경보건학회지
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• 제50권5호
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• pp.311-321
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• 2024

Background: People spend 80~90% of their day indoors, with only 10~20% of their time spent outdoors. Evaluating exposure accurately requires assessments based on an individual's time-activity pattern. Objectives: The purpose of this study is to evaluate the exposure and contribution rates of PM_2.5 by microenvironment, identify related exposure factors, and suggest management measures and priorities. Methods: This study analyzed the time-activity patterns of 3,984 weekday respondents in Seoul using data from the 2014 Time-Use Survey by Statistics Korea. The respondents were clustered, and occupational groups were estimated by conducting a frequency analysis of sociodemographic factors. Location data was collected at 10-minute intervals, followed by exposure scenario construction and active simulations. When calculating the exposure and contribution rates of PM_2.5, the Korean exposure factors handbook was used to account for inhalation rates. Results: Most of the indoor microenvironments where people spend their time are residential. Students spend the most time indoors at 22.7 hours per day, followed by senior citizens at 22.5 hours, office workers at 22.0 hours, and stay-at-home parents at 21.8 hours. Although people spend little time in spaces such as outdoors, in transportation, and other indoor microenvironments, higher PM_2.5 concentrations significantly increase the contribution rates. Among all clusters, even though cluster 10 (office workers) and cluster 2 (night security workers) spend relatively little time in other indoor microenvironments, such as Korean barbecue restaurants and pubs, they were included in the scenarios, resulting in higher exposure concentrations and contribution rates. Conclusions: The analysis of PM_2.5 exposure contribution rates by microenvironment revealed that the highest exposure occurred in the 'other indoor' category, with Korean barbecue restaurants showing the highest concentration levels among them. Based on the PM_2.5 exposure contribution rates in the microenvironments, this study suggests priority locations and population groups for targeted management.

• 농업과학연구
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• 제31권2호
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• pp.135-148
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• 2004

Rice is not only main food but also key farm income source of Korean farmers. In spite of the above facts, rice productivity was decreased on account of drought in every 2 or 3 years interval owing to the vulnerability of irrigation facilities throughout Korea in the past decades. As an context of the first five year economic development plan, all weather farming programme including 4 big river basin comprehensive development projects and large and medium sized irrigation water development projects were carried out successfully. Therefore the area of irrigated paddy were increased from 58% in 1970 to 76.2% in 1999. In the past decades, the Government had invested heavy financial funds to develop irrigation water but as an factor share analysis, the contribution rates of irrigation water and investment for farmland base development project have not been identified yet in national agricultural economic level. It is very scarce to find out the papers concerned to macro-economic factor share analysis or contribution rates of water and investment cost to rice production value in Korea considering the production function of the quantity of irrigation water and investment cost as independent variables. Accordingly this paper covered and aimed at identifying (1) derivation of rice production function with the time serial data from 1965 to 1999 and the contribution rates of irrigation water and total investment cost for farmland base development project. The analytical model of the contribution rates was adapted the famous Cobb-Douglass production function. According to the model analysis, the contribution rate of irrigation water to rice production in Korea was shown 37.8% which was equivalent to 0.28 of the production elasticity of water. The contribution rate of farmland base development project cost was revealed 22% and direct production cost of rice was contributed 60% in the growth of rice production and farm mechanization costs contributed to 18% of it respectively. The two contribution rates comparing with the direct production cost were small but without irrigation water and farmland base development, application of high-pay off inputs and farm mechanization might be impossible. Considering the food security and to cope with the frequent drought, rice farming and investment for the irrigation water development should be continued even in WTO system.

• KDI Journal of Economic Policy
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• 제12권1호
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• pp.3-29
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• 1990

60년대 전반 이후의 수출주도형(輸出主導型) 공업화(工業化)을 통한 고도성장(高度成長)은 국내산업(國內産業) 또는 업종간(業種間) 성장율(成長率)의 차이로 인해서 상당한 산업구조변화(産業構造變化)를 수반했다. 따라서 본 논문에서는 산업연관표체계(産業聯關表體系)를 사용하여 우리나라의 장기적(長期的)인 산업성장(産業成長) 및 구조변화(構造變化)의 요인(要因)을 분석해 보고자 한다. 즉 과거(過去)의 장기적(長期的)인 성장과정(成長過程)에서 국내수요(國內需要), 수출(輸出), 수입대체(輸入代替)와 기술변화(技術變化)는 산업별 생산성장(生産成長)에 각각 얼마만큼 기여(寄與)했나 하는 것을 측정해 보고자 한다. 이러한 측정은 총량적(總量的) 경제수준(經濟水準)뿐만 아니라 세부산업별(細部産業別)로도 이루어질 수 있기 때문에 한국경제(韓國經濟) 전반(全般) 및 공업부문(工業部門)의 세부적(細部的) 변화과정(變化過程)에 관한 풍부한 분석자료(分析資料)를 제공할 것으로 기대한다.

• 한국물환경학회지
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• 제26권6호
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• pp.1016-1027
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• 2010

The phosphorus contribution rate on water quality of North and South-Han River, and Gyungan-cheon by effluents from environmental fundamental facilities located in upstream basin of Paldang Lake were analyzed. QUALKO2 model was selected for the analysis of contrubution rate, and was constructed considering the location of the main point sources and all facilities in study area. The pollutant loading rates and arrival rates for each unit-watershed in study area were calculated for model operation. For the calibration and verification of model, 2006 water quality dataset from Ministry of Environment and the effluent loadings of the environmental fundamental facilities were used. Reliability Index (RI) method was used to estimate the validity of the results of calibration and verification. The phosphorous contribution rate(%) for each environmental fundamental facility were analyzed by excepting the effluent loading of the facility. The contribution rate was analyzed for each facility, facility groups separated by each main river and each unit-watershed. The main results of analysis for each facility are as follows; (i) the phosphorous contribution of B1 facility is 50%, which is the highest phosphorous contribution rate among those of nine facilities in the North-Han River Basin; (ii) the highest phosphorous contribution is 55.6% from J facility among eight facilities in the Gyungan Stream Basin; (iii) 40% from E treatment facility is the highest among those of twenty eight facilities in the South-Han River Basin.

• 상하수도학회지
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• 제33권1호
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• pp.43-53
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• 2019

In the Geumho River, 4-nitrophenol has been detected, thus it is necessary to investigate the contamination sources in order to prevent the release of this compound. However, the research to estimate the potential source is regarded as complicated research. In this study, the distributions of 4-nitrophenol were simulated and the contribution of the potential sources was estimated using a numerical model(HydroGeoSphere; HGS) and the measuring data of 4-nitrophenol from 2013 to 2017. The altitude data, the land cover data, the flow rates of the tributaries and wastewater treatment plants, and the decay rate of 4-nitrophenol was used as the input data. The results of this research showed that the contribution rates of potential contamination sources in the upstream area were higher than that of the downstream area. Most of the upstream area is the agricultural area, it seemed that 4-nitrophenol was originated from the pesticides. In order to achieve more specific location of sources, an intensive investigation in the upstream is required.

• 대한지역사회영양학회지
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• 제25권1호
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• pp.32-47
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• 2020

Objectives: Calcium (Ca) is an insufficiently consumed nutrient, whereas phosphorus (P) intake has exceeded the recommended intake level in Korea over the past decade. The purpose of this study was to analyze dietary Ca and P intakes and their contribution rate according to dish groups. Methods: A 24-hour dietary recall survey of 640 healthy adults (aged 19-69 years) was undertaken twice in four Korean provinces. Dietary Ca and P intakes and their rates of contribution from 31 major dish groups were analyzed and compared by gender, age group, and region. Results: The average Ca and P intakes of the subjects were 542.1 ± 222.2 mg/d and 1,068.3 ± 329.0 mg/d, respectively. The intakes of Ca and P as percentages of recommended nutrients intake (RNI%) were 71.7 ± 29.8% and 152.6 ± 47%, respectively, and the percentages under the estimated average requirement were 60.3% for Ca and 3.8% for P. The RNI% of Ca was not significantly different between males and females, but was significantly higher in subjects in the sixties age group than in other age groups and was significantly lower in the Korean capital than in other regions. The RNI% of P did not significantly differ by gender or age groups, but it was significantly higher in the capital than in Gyeong-sang. The five major dish groups contributing to Ca intake (contribution rate) were milks/dairy products 69.2 ± 109.2 mg/d (12.6%), soups 55.6 ± 69.6 mg/d (10.1%), stir-fried foods 53.1 ± 70.7 mg/d (9.7%), stews 43.4 ± 85.4 mg/d (7.9%), and kimchi 38.4 ± 31.8 mg/d (7.0%). The five major dish group contributing to P intake (contribution rate) were cooked rice 160.7 ± 107.1 mg/d (14.9%), stir-fried foods 88.5 ± 89.4 mg/d (8.2%), soups 76.7 ± 85.8 mg/d (7.1%), one-dish meals 63.3 ± 94.4 mg/d (5.9%), and stews 62.6 ± 89.3 mg/d (5.8%). The dish groups contributing to Ca and P intakes differed somewhat by gender, age group, and region. Conclusions: Programs to improve the nutritional status of Ca and P intakes should consider the differences in Ca and P contribution rates by dish groups as well as by gender, age group, and region.

• 해양환경안전학회지
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• 제8권2호
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• pp.39-44
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• 2002

In order to study the change of pollution loads flowing into Mokpo harbour after the operation of Mokpo Municipal Sewage Treatment Plant (MMSTP) and to evaluate the contribution of MMSTP operation to the improvement of marine water quality of Mokpo harbour, the pollution loads flowing into Mokpo harbour from land in dry weather were surveyed and estimated on the bases of the seasonal flow rates and the seasonal water qualities of streams and effluents located around Mokpo harbour from summer, 1997 to spring, 1998 before the operation of MMSTP, and the pollution loads of the inflow and the effluent of MMSTP were also surveyed and estimated from winter, 1998 to spring, 1999 after the operation of MMSTP. The treatment rates of MMSTP were shown to be about 49% in COD, 76% in TSS, 79% in VSS, 3% in T-N, 7% in DIP, 29% in T-P and -32% in DIN. The change rates of pollution loads flowing into the inner harbour of Mokpo due to the operation of MMSTP were shown to be about 56% In COD, 78% in TSS, 84% in VSS, 45% in DIN, 22% in T-N, 34% in T-P and -14% in DIP. The contribution rates of MMSTP operation to the reduction of total pollution loads flowing into the entire Mokpo harbour were found to be about 3% in COD, 3% in 755,5% in VSS,1% in DIP, 3% in T-P and -1% in DIN.

• International Journal of Advanced Culture Technology
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• 제12권2호
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• pp.62-71
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• 2024

The Study analyzed the effect of private education costs and housing prices on the total fertility rates in 16 metropolitan cities in Korea from 2009 to 2021, and estimated the contribution rates of each variable on the decrease in the total fertility rate. Using a dynamic panel data model considering the time series correlation of the total fertility rates, the total fertility rates for the year was positively (+) affected by the total fertility rates of the previous year, and the increase in apartment sales and Jeonse prices in the previous year reduced the total fertility rates. In addition, the increase in private education costs per capita in the previous year was analyzed to consistently reduce the total fertility rates.

• 한국안전학회지
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• 제15권4호
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• pp.150-156
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• 2000

In this paper, the human error contributions to the system unavailability are calculated and compared to the mechanical failure contributions. The system unavailability is a probability that a system is in the failed state at time t, given that it was the normal state at time zero. It is a function of human errors committed during maintenance and tests, component failure rates, surveillance test intervals, and allowed outage time. The THERP (Technique for Human Error Rate Prediction), generally called "HRA handbook", is used here for evaluating human error rates. This method treats the operator as one of the system components, and human reliability is assessed in the same manner as that of components. Based on the calculation results, the human error contribution to the system unavailability is shown to be more important than the mechanical failure contribution in the example system. It is also demonstrated that this method is very flexible in that it can be applied to any hazardous facilities, such as gas valve stations and chemical process plants.ss plants.

• The Journal of the Acoustical Society of Korea
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• 제16권3E호
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• pp.44-49
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• 1997

In this paper, we propose an adaptive encoding method of fixed codebook in CELP coders and implement an adaptive fixed code exited linear prediction(AF-CELP) speech coder. AF-CELP exploits the fact that the fixed codebook contribution to speech signal is also periodic like the adaptive codebook (or pitch filter) contribution. By modeling the fixed code book with the pitch lag and the gain from the adaptive codebook, AF-CELP can be implemented at low bit rates as well as low complexity. Listening tests show that a 6.4 kbit/s AF-CELP has a comparable quality to the 8 kbit/s CS-ACELP in background noise conditions.