• The Journal of Information Technology
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• v.1 no.2
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• pp.119-141
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• 1998

The main contents of WTO agricultural product agreement are composed of $\circled1$ market access $\circled2$ domestic subsidy and reduction of export subsidy $\circled3$ preferences for developing countries. But there still remains the possibility of laying a protection barrier within WTO regulations. That is to say, with the application of quota system, tariff rate quota system, or different quotas on different countries, and with the practices of government control trade and mark up. This paper is for studying the application of these protection barriers to minimize the impact of agricultural market opening.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1942_1943
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• 2009

무선통신 시스템의 소형화와 저가격, 고품질, 다기능 재료 및 첨단 가공 기술과 연계된 필터설계 및 제작 기술에 대한 연구가 활발히 진행 중이다. 그러나 무선통신 시스템은 주파수라는 한정된 자원을 사용하기 때문에 주파수 자원의 효율적 관리를 위한 규제나 방안이 필요하고. 이에 따라서 여러 가지 대책과 방안이 필요로 하고 있다. 그래서 필터의 성능개선을 위한 연구가 본질 적으로 중요하게 되었다. 본 논문은 체비세프(Chebyshev)필터와 버터워스(Butterworth)필터를 이용한 대역통과(band pass) 필터를 제안한다. 이 필터는 안정화된 통과대역과 빠른 주파수 응답을 얻기위해 6차 체비세프필터와 8차 버터워스필터를 결합 하였다. 측정된 대역통과 필터는, 차단 영역을 구분하는 스커트(skirt)특성은 날카롭게(sharp) 되었고 통과대역의 평탄도 또한 개선되어짐을 볼 수 있다. 제안된 필터의 중심주파수는 2.5GHz, 대역폭은 200MHz이고, 대역내 평탄도는 0.5dB, 경사도는 오차가 60dB일때 체비세프는 210MHz, 버터워스는 340MHz, 체비세프-버터워스는 290MHz가 되어 버터워스 보다 좋게 되었으며 극점의 배치도 안정적인 결과를 얻었다.

• Tunnel and Underground Space
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• v.16 no.2 s.61
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• pp.146-155
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• 2006

The target slope of this study, formed during the construction of highway, is the very high infinite slope where sliding began along the discontinuity. Although an attempt was made to stabilize the upper part of the slope by installing the rock anchors, large scale failure was occurred at the lower part if the reinforced area. Afterwards, subsequent failures were observed two times. To investigate the cause of the failure, residual shear strength was measured by performing the direct shear test of rock specimen of the site. The anchor design was based on the pull-out test. Considering the slope surface where the undulation was severe and the variation of strength was very large, buttressing was used to obtain the required anchoring capacity.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.456-460
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• 2016

최근 기후변화의 영향과 급격한 도시화로 인한 하천 저류능력의 감소 및 부적절한 하수시설의 설계로 도시유역의 홍수 위험성이 증가하면서 적극적인 구조물적 홍수방어대책으로 대심도터널의 활용에 대한 필요성이 대두되고 있다. 일본을 비롯한 외국에서는 대심도터널의 활용이 적극적으로 고려되고 있으며 실제 설치 및 운영 사례 또한 증가하고 있다. 그러나 국내에서는 아직까지 홍수 방어용 대심도터널의 설치 및 운영된 사례가 없고 설계 및 시공과 관련한 기준 및 연구가 미미한 실정이다. 본 연구에서는 대심도터널 내부에서의 이상흐름 거동특성을 구명하기 위하여 터널을 모형화한 수평관에서 실험적 연구를 수행하였다. 직경 100 mm 투명 아크릴관으로 제작된 수평관 내부를 흐르는 물에 공기를 주입하여 기포를 발생시키고 전기전도계를 이용하여 유속변화에 따른 관에서의 물-공기 혼합 이상흐름의 거동특성에 대해 살펴보았다. 실험결과 터널 계통 전반에서의 물-공기(이상류) 거동 특성을 파악할 수 있었다. 이를 통해 대심도터널 내부 공기에 대한 효과적인 제어로 흐름의 안정화 및 그에 따른 수리성능의 개선효과를 기대할 수 있으며, 도시지역의 집중강우로 인한 수방재 대응 기술개발을 위한 기초자료로 활용할 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.29-29
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• 2020

가뭄으로 인한 영향은 상당 기간 완만히 누적되어 나타나고, 해갈된 후에도 수년 동안 파급효과가 나타날 수 있으므로 모니터링 및 예·경보에 어려움이 있다. 가뭄 리질리언스 확보를 위해서는 지하수개발, 해수담수화, 식수전용 댐 확충 등 구조적 중장기 안정화 방안과 더불어 가뭄 피해를 예측하여 미리 물 자원을 확보하는 비구조적 대응 방안이 같이 이루어져야 한다. 대상지역은 물 부족을 겪고 있는 미급수 지역으로 환경부에서는 구조적 대책으로 샌드댐 설치가 예정되어 있다. 본 연구에서는 비구조적 가뭄 대응을 위하여 하천-취수원 연계 모니터링 및 분석을 수행하였다. 하천에 수위 계측기를 설치하여 시간별 수위를 상시 계측하였으며, 월 1회 유속을 측정하여 일별 유량(공급량)을 모니터링하였다. 이를 통해 도출된 일별 유출량 값은 장기유출모형인 SWAT의 매개변수 검·보정에 이용되었으며, 과거 10여 년간의 유출량(공급량)을 추정하였다. 또한, 취수원인 물탱크에 수위계를 설치하여 낮 동안 수위 변화량을 이용량을 가정하여 일별 수요량을 추정하였다. 최종적으로 일별 수요량-공급량 관계분석을 통해 가뭄에 대응할 수 있는 체계를 구축하였다.

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.517-528
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• 2009

Statistical analyses of cut-slope stability were performed over approximately 5.7 km section along the National road No. 25, which cross-cuts in NW-SE direction the Cheongwon and Boeun-Gun area, Chungbuk. A measure of slope-stability was established by using direct reinforcement and indirect protection methods in whole section. Orientations(dip/dip direction) of the slopes, foliations(bedding), cleavages and joints were measured in total of 30 slope sites. The results analyzed using stereographic projection indicate that major directions of the slopes come out predominantly in three directions: 1) $58^{\circ}/095^{\circ}$, 2) $60^{\circ}/296^{\circ}$ and 3) $59^{\circ}/212^{\circ}$. In analyses of dip direction and frequency of cut-slopes established by reinforcement and protection methods, slopes with dip direction of $80-120^{\circ}$ and $280-320^{\circ}$ mostly occur. However, slopes with dip direction of $0-80^{\circ}$(N and NW) and $120-160^{\circ}$(SE) are not distributed in the study area. Failure aspects were analyzed for three major directions of the slopes, respectively. The results of failure aspects analyzed indicate that slopes in the study area could generate various failures as the results of intersection and/or intersection combination among joints, foliations(bedding) and cleavages. However, possibility of failure in a slope of major direction No. 3 is statistically very low because of low frequency in total number of slopes with the direction and of formation of small scale-slopes geographically, although the slope might generate all aspects of failure-modes.

• The Journal of Engineering Geology
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• v.23 no.2
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• pp.149-160
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• 2013

Volcanic activity commonly creates a highly complicated volcanic complex due to the admixture of lava flow and sedimentation of volcanic ash. The Song-Gok site is composed of volcanic rocks that collapsed at the lower part of the slope, in combination with several discontinuities in and around a fault. The results of projection analysis indicated the possibility of plane, wedge, and toppling failure in the failure section. The results of discontinuity modeling using the Distinct Element Method (DEM) revealed a total displacement of 207 mm and a joint shear displacement of 114 mm. The yield surface zone was verified at the fault plane of the failure section. In geotechnical terms, volcanic rock slopes are characteristically vulnerable to failure because of differential weathering among the various rock types, the effect of groundwater based on the permeability of the rocks, and the presence of systematic joints generated by the cooling and contraction of lava. When considering the stability of a volcanic rock slope, it is necessary to consider data such as the geological features of the rock, as obtained through detailed geological survey, and variations in discontinuities and rock blocks.

• Journal of the Korean GEO-environmental Society
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• v.1 no.1
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• pp.79-85
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• 2000

The environmental assessment on the open dumping landfill of small scale which was situated in local small city was carried out to reuse the landfill site as the residental, commercial and other purposes through the analysis of the leachate of landfill, extracted solution from landfill waste. The waste was landfilled at 5.5~8m depth and the covered layer so poor as 20~50cm thickness. The biodegradable organic matters were almost degraded and the result of the leachate of landfill showed that the BOD/COD ratio were measured as 0.079, pH 7.2~7.6, SS 47736mg/L, COD 6193.8mg/L, T-N 596mg/L, and T-P 123.9mg/L respectively. These results were higher than those of extracted solution of landfill waste as the COD and BOD were measured as low values and T-N 7.77mg/L and T-P as 0.20mg/L lower concentrations the landfill appears the maturation phase. As the result of the assessment on the open dumping landfill of small scale, if appears that this landfill is maturation phase and the formation leachate is reduced. If the treatment facility of leachate from landfill and the layer which protects the inflow/infiltration is prepared, it can be safely used as this landfill site.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.312-320
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• 1996

This study was to investigate the changes of phytotoxicity of food waste during composting at an aerated static pile for 80 days. The concentration of sodium in the final compost increased by more than 30% and almost of the sodium was a water soluble type which corresponds to about 94% of the total concentration. Major volatile fatty acid(VFA) produced during the composting was acetic acid and also somewhat of butyric acid. High concentration of acetic acid during the composting was kept up for a month and then decreased progressively. It suggests that the phytotoxicity by the VFAs produced during composting of food waste could be removed through a stabilization process in a period of about 40 days. From the statistical analysis between germination index(G.I.) and VFAs. or G.I. and sodium, the phytotoxicity of food waste samples was more dependent in the changes of acetic acid concentration than that of sodium concentration. Considering low G.I. value in the final food waste compost which is matured completely, however. the agricultural utilization of the food waste compost may be to have a big problem due to excess sodium of the compost which is impossible to remove by composting and seriously inhibits growth of plants.

• Clean Technology
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• v.12 no.3
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• pp.113-127
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• 2006

Waste lubricating oil(WLO)s have been recycled as energy source through direct fuel in cement kilns and fossil power plants, or as fuel oils, or re-refined lubricating base oils. In our country, they have been recycled as low grade fuel oil through chemical treatment process. In 2003, extended producer responsibility (EPR) system was adopted from deposit system on sale of lubricating oils in order to promote their recycleing rate. However, our recycling rate of WLOs have been stagnant(below 70%) for last 5 years. And there has been no research work on recycling of WLOs as re-refined base oil until now in this country. Stabilization technology of thermally cracked oils to reduce tar and malodor and to improve their color for production of high grade fuel oil, and a novel process production of high grade re-refined lubricating base oil from WLOs have been developed and commercialized recently in Canada and U.S.A., respectively. Several countries like Australia, Italy, Germany and U.S.A., etc. are encouraging recycling companies to recycle WLOs as re-refined lubricating oil by giving greater subsidies or benefits compared to other recycling methods. They also adopt a policy to purchase re-refined lubricating oil preferentially in the federal or local governments and to recommend consumers to purchase it willingly. Based on the facts that several advanced countries have adopted a policy to recycle WLOs as re-refined base oil for saving of petroleum resource and reduction of environmental pollution, it is right time to be considered that our present policy for recycling of WLOs should be reevaluated and the new policy of their environmental-friendly and sustainable recycling should be established.