• 대한인간공학회지
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• 제29권1호
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• pp.101-105
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• 2010

According to the Korea National Statistical Office data in 2008, the population over ages of 65 years would possess to 10.7% whole population of Korea in 2009 denoting Korea is already in the aging society. It is well-known that the possibility to work longer and to live better is highly related to the work ability of individuals. The objective of this study is to evaluate the work ability of each aged group using the Work Ability Index(WAI) in the shipbuilding industry, machinery industry and Korea housing corporation, and to assess the effect of the type of business, age and job on the WAI score. The results showed that no significant difference was identified on the effect of aging although work ability of some group(over 55 years) was a little higher than that of others. Also, type of business and job had a significant effect on WAI score. These results suggested that the work ability is not necessarily related to aging in Korean society. One possible explanation for this might be different cultural characteristics of Korean society.

• KCI Concrete Journal
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• 제12권1호
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• pp.139-144
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• 2000

Ground Penetrating Radar (GPR) with 1 GHz antenna has been used to locate a steel bar embedded inside laboratory-prepared mortar specimens. Four mortar specimens are made with the dimensions of 100 cm (length) x 100 cm (width) x 14 cm (depth). One specimen had no bars and the other three specimens had a Dl9 steel bar at 4, 6. and 8 cm depth. As a part of the experimental work, the dielectric constants of mortar specimens are measured during curing. As the curing time increased. the dielectric constant decreased with decreasing moisture content inside the specimen. The steel bar embedded inside mortar specimens has been successfully identified in all three cases. The results using signal processing scheme developed in this study significantly improved the output of a commercially available radar system.

• 설비공학논문집
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• 제20권4호
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• pp.274-279
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• 2008

In the perspective of saving energy in buildings, high performance of insulation and air tightness for improving the heating and the cooling efficiency has brought the positive effect in an economical view. However, these building energy saving technologies cause the lack of ventilation, which is the direct cause of increasing the indoor contaminants, and it is also very harmful to residents because they spend over 90% of their time in the indoor area. Therefore, the ventilation is important to keep indoor environment clean and it can also save energy consumption. In this study, a HEPA type breathing wall is designed as a passive ventilation system to collect airborne particles and to supply fresh outdoor air. To make fine porous structures, polymer nano fibers which were made by electro spinning method are used as a precursor. The nano fibers are coated with SiO2 nano particles and finally the HEPA type breathing wall is made by sintering in the electric furnace at $300\sim500^{\circ}C$. The pressure drops of nano ceramic structure are 8.2, 25.5 and 44.9 mmAq at the face velocity of 2.0, 5.9 and 8.8 cm/s, respectively. Also the water vapor permeability is $3.6g/m^2{\cdot}h{\cdot}mmHg$. In this research, the porous nano ceramic structures are obtained and the possibility for the usage of a material for HEPA type breathing wall can be obtained.

• 설비공학논문집
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• 제20권12호
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• pp.820-824
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, the electret filter is made by electrospinning process using Polystyrene which is dissolved by 5 : 5 of Tetrahydrofuran (THF) and Dimethylformamide (DMF). Also the electrical properties and the filtration performances of electrospun filter media are Quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. The surface charge potential and the surface charge density of electrospun PS filters are increased with increasing applied voltage and saturated at 30 kV of applied voltage. Also collection efficiency of electro spun filters is increased with increasing surface charge potential and surface charge density. But the surface charge potential is decreased by natural decay and it causes deterioration of particle collection efficiency.

• KIEAE Journal
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• 제13권5호
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• pp.17-22
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• 2013

This study aims at proposing a sound and sustainable development direction of an urban commercial district by identifying space syntactic properties, from the perspective of human ecology, of the street network in Enuengjeongi culture street as the representative commercial district of Daejeon City in Korea. The results are obtained through Angular Segment Analysis (ASA) on the street network in subject area for this study. It was found that most of the socially integrated nodes are arranged along the axis of main street in the district. However, in some of those nodes, it was investigated that the social integrative function have weakened, because open spaces as public space for the general public are occupied illegally by commercial purposes of shops and car parking. It was found that the socially isolated nodes are located at the district boundary connected to a relative narrow street, with a relatively low density of the commercial facilities. Besides, it was identified that a street width in the commercial district may be a factor affecting the social integration of a space on the basis of the openness of the space.

• 대한환경공학회지
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• 제27권1호
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• pp.93-100
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• 2005

본 연구는 1차슬러지와 생물학적 영양소제거 슬러지의 처리에 있어서 분리 및 혼합처리에 대한 농축과 탈수특성을 조사하였다. 슬러지의 탈수를 위해서는 고분자 폴리머, 증기주입 및 초음파처리등의 슬러지 개량방법을 이용하여 슬러지의 개량특성을 분석하였고, 비저항계수측정법과 Wedge zone simulator 그리고 원심분리를 이용하여 탈수특성을 분석하였다. 농축실험결과 1차슬러지와 생물학적 2차슬러지를 분리농축하는 것이 바람직한 것으로 나타났으며, 특히 3.5%이상의 고농도 1차슬러지의 경우는 농축단계에서 상징수의 고액분리는 부정적이었다. 농축된 슬러지의 개량에 있어서는 폴리머 주입, 증기처리 및 초음파처리 등의 개랑법중에서 폴리머를 주입한 경우가 가장 우수한 탈수성을 나타내었다. 1차와 2차 및 혼합슬러지의 최적 폴리머 주입조건은 건조고형물 기준으로 각각 0.26%, 0.43% 및 0.38%이었다. 농축슬러지의 탈수실험에서는 1차와 2차슬러지를 혼합하여 처리하는 것이 고액분리측면에서나 반류수의 수질측면에서 보다 효과적으로 나타났다. 여과포를 이용하는 탈수방식은 폴리머의 사용이 필수적이었으나 이 경우 2차슬러지의 단독탈수는 효과가 없었다. 원심탈수 방법은 가장 우수한 탈수효율을 보였으며, 이때 폴리머의 주입으로 탈수케익의 고형물함량을 조금 더 향상시킬 수 있었다. 이상의 실험결과에 근거하여 반류수의 수질특성과 고형물회수를 고려한 합리적인 슬러지 처리공정을 제안하였다.

• Journal of Ecology and Environment
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• 제38권3호
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• pp.281-291
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• 2015

To clarify the effects of forest fire on the carbon budget of a forest ecosystem, this study compared the seasonal variation of soil respiration, net primary production and net ecosystem production (NEP) over the year in unburned and burned Pinus densiflora forest areas. The annual net carbon storage (i.e., NPP) was $5.75t\;C\;ha^{-1}$ in the unburned site and $2.14t\;C\;ha^{-1}$ in the burned site in 2012. The temperature sensitivity of soil respiration (i.e., $Q_{10}$ value) was higher in the unburned site than in the burned site. The annual soil respiration rate was estimated by the exponential regression equation with the soil temperatures continuously measured at the soil depth of 10 cm. The estimated annual soil respiration and heterotrophic respiration (HR) rates were 8.66 and $4.50t\;C\;ha^{-1}yr^{-1}$ in the unburned site and 4.08 and $2.12t\;C\;ha^{-1}yr^{-1}$ in the burned site, respectively. The estimated annual NEP in the unburned and burned forest areas was found to be 1.25 and $0.02t\;C\;ha^{-1}yr^{-1}$, respectively. Our results indicate that the differences of carbon budget and cycling between both study sites are considerably correlated with the losses of living plant biomass, insufficient nutrients and low organic materials in the forest soil due to severe damages caused by the forest fire. The burned Pinus densiflora forest area requires at least 50 years to attain the natural conditions of the forest ecosystem prior to the forest fire.

• 현장농수산연구지
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• 제10권1호
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• pp.101-111
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• 2008

As the quality of life improves, people want to live in more pleasant environment with beautiful trees, clean air and water. They are keenly interested in environmental issues as well as living environment of apartment which is a trademark of modern life. With this situation, the function and roles of landscaping trees have been recognized as a critical factor to improve living environment. As people have asked for more demands on those trees, it has raised more issues on the defect of trees and is required the solution to those issues. So, the purpose of this study was to survey the reasons of defects and find out those solutions. The data on defects in 1990s was referenced to the reports issued by SH Corporation in 1994 and 1997. The data on defects in 2000s are collected from March, 2006 to May 2006 based on the survey for apartments already constructed by Korea Housing Corporation. The results of the survey were shown that, in the year of 1994, landscaping trees causing high rate of defects were Acer buergerianum (92%), Pinus densiflora(85.7%), Celtis sinensis(80%), Cydonia sinensis(75%) and Diospyros kaki(66.6%), and in the year of 1997, landscaping trees causing high rate of defect were Ziziphus jujuba(100%), Cornus alba(65.2%), Diospyros kaki(60%), Thuja occidentalis(60%), and Metasequoia glyptostroboides(42%). And, in the year of 2006, landscaping trees causing high rate of defect were Sophora japonica(100%), Taxus cuspidata(80%), Magnoila quinquepeta (75%), Acer palmatum(62.5%) and Ginkgo biloba(50%). Because the reasons of defects were various according to the conditions including the climate, location, time and landscaping trees carried into the work area, we present the problems and solutions to those defects. Since the landscaping trees are living creatures, the factors of defects were various and complicated according to the site condition. So, in the period of warranty, contractor should designate the tree manger who can recognize the situation and take suitable action within timely manner.

• 국토계획
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• 제54권7호
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• pp.5-23
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• 2019

The central government has implemented policies to strengthen the competitiveness of small and medium sized cities for balanced development at the national scale. However, since it is often difficult to enhance the competitiveness through partial projects of each jurisdiction, many local governments collaborate at the regional scale. This suggests that a regional approach is important for the management of small and medium sized cities. On the one hand, the concept of network city suggests that various functional networks can affect the growth of small and medium sized cities. Given this background, the purposes of this study are to delineate regional boundaries at national scale and identify their relations of growth by using functional network and Moran's I index. The study uses the Markov-chain model and cluster analysis to delineate the regions, and Moran's I is employed to identify the relations of growth. The results show that interactions between jurisdictions through networks could be crucial factors for growth of small and medium sized cities, while the networks based on passenger travel and freight movement have different implications. The results suggest that policy makers should not only consider local level investments, but also take the characteristics of networks between cities into account for achieving balanced development and developing regeneration policies.

• 한국터널지하공간학회 논문집
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• 제20권1호
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• pp.119-130
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• 2018

기존 공동구에 관한 VE/LCC 연구는 정량적 방법을 통하여 편익(7개 항목), 비용(5개 항목)에 대하여 서울시의 주요 10개노선을 대상으로 비용-편익 분석을 통한 공동구의 경제적 타당성을 검토하였다. 기존 공동구에 관한 VE/LCC 연구는 정량적 방법을 통하여 편익(7개 항목), 비용(5개 항목)에 대하여 분석을 수행하였다. 이에 본 논문에서는 3개의 항목(교통사고감소, 차량소음저감, 사회 경제 손실)을 추가하여 서울시 주간선도로 61개 구간에 대하여 경제성 평가를 분석 하였다. 교통사고감소 항목은 사업시행으로 절감할 수 있는 교통사고 비용을 개량화한 것이며, 차량소음저감 항목은 사업시행으로 발생하는 소음 변화량을 나타낸 지표이다. 마지막으로 사회 경제손실 항목은 공동구의 시공으로 인하여 지역경제에 미치는 영향을 금액으로 나타낸 것이다. 편익은 10개의 항목, 비용은 8개의 항목들 중 우선 추가 항목들의 금액을 비교 분석 하였으며, 개착식 및 터널식 공동구에서 추가된 항목들과 전체 항목들이 각 분석에 미치는 영향 정도를 분석하였다. 분석의 결과로 공동구 경제성 평가시 기초 및 상세 모델에 적용되는 항목들을 분석하여 공동구 설계시 보다 효율적인 경제성 평가가 가능하도록 하였다. 본 연구에서 추가로 제시된 항목들을 포함한 기초 및 상세 모델의 경제성 평가는 공동구 설계시 자주 활용될 것으로 판단된다.