• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.121-125
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• 2007

대구시는 여름철을 제외하고 서북서풍내지 서풍으로 서풍계열의 바람이 우세하여 지리적으로 서쪽에 위치한 공장지대와 신흥 부도심의 영향이 도심지 내부에 크게 나타날 수밖에 없는 그런 구조를 가지고 있으므로 도심내의 녹지공원 조성과 같은 오아시스 효과로 자연형 대기 순환 구조를 구축하지 않을 경우 환경오염과 지구온난화로 인한 심각한 피해가 초래할 수 있으므로 친환경도시를 위한 준비를 소홀히 해서는 않된다고 사료된다. 아울러 대구광역시의 연평균 대기오염물질의 농도는 $PM_{10}$, $NO_2$ 제외하고 환경기준을 초과한 것은 없으며, 주로 자동차와 주변 공장에 의한 오염원이 대부분임을 알 수 있었다. 또한 $PM_{10}$의 경우 대구시에 산재한 환경측정만 대부분의 지점에서 환경기준을 초과하고 있으므로 디젤 자동차 및 비산먼지 저감 등 미세분진에 대한 저감 대책을 신속히 마련하여야 한다고 생각한다. 그리고 대구시의 $O_3$과 $PM_{10}$의 고농도 현상은 고기압이 장시간 우리나라를 지배하면서 대기가 안정되고 바람이 약하여 국지풍의 발달이 용이할 경우 도심지내에 고농도 오염을 야기하고 있으며 지형적으로 도심의 오염물이 다른 지역으로 수송되거나 확산이 용이하지 않는 지형구조를 갖고 있으므로 도심을 흐르는 신천을 바람통로 이용하고 도심에 녹지공간 형성 및 도심지의 불투수성 지표면을 잔디 이식을 통한 자연형 도로로 바꾸어 줌으로서 도심내의 열 축적 현상을 줄이고 증발산을 도울 수 있는 cold island 역할을 증대시킬 수 있을 것이다. 이와 같은 사업은 풍속이 약하고 건조한 독일을 포함한 유럽의 내륙지방에서 활발하며 최근에는 해안에 있는 대도시에 저온의 해풍 또는 강바람을 도심에 유입시켜 도시열섬을 완화하고자 하는 시도가 일본을 포함한 아시아 국가에서 많은 관심을 가지고 있다(Ichinose, 1999, 2000; 김해동 외, 2002).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.6
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• pp.298-304
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• 2009

The effect of the surface treatments on the high temperature properties of the Inconel 617, one of the promising candidate alloys for high temperature heat-transport system, has been studied. Various surface modification methods including a rapid thermal process(RTP), a hydrothermal treatment, and a physical vapor deposition($2{\mu}m$ thick TiAlN film by an arc discharge) were applied to the Inconel 617. The morphological and the structural properties of the surface-modified Inconel 617 samples after heat treatment at $1000^{\circ}C$ in the air were compared to find out whether inhomogeneous formation of $Cr_2O_3$ crust at the surface region was suppressed or not. TiAlN-coated Inconel 617 showed homogeneous microstructure and the lowest wear loss compared to bare, RTP- and hydrothermally-treated Inconel 617 by suppressing the $Cr_2O_3$ crust formation.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1731-1737
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• 2007

This paper considers subway routing problem. Given a schedule of train to be routed by a railway stock, the routing problem determines a sequence of trains while satisfying turnaround time and maintenance restrictions. Generally, the solution of routing problem is generated from set partition formulation solved by column generation method, a typical integer programming approach for train-set. However, we find the characteristics of metropolitan subway which has a simple rail network, a few end stations and 13 departure-arrival patterns. We reflect a turn-around constraint due to spatial limitations has no existence in conventional railroad. Our objective is to minimize the number of daily train-sets. In this paper, we develop two basic techniques that solve the subway routing problem in a reasonable time. In first stage, we formulate the routing problem as a Min-cost-flow problem. Then, in the second stage, we attempt to normalize the distance covered to each routes and reduce the travel distance using our heuristic approach. Applied to the current daily timetable, we could find the subway routings, which is an approximately 14% improvement on the number of train-sets reducing 15% of maximum traveling distance and 8% of the standard deviation.

• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.88-94
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• 2008

The concentration of atmospheric carbon dioxide (CO2), which is one of the major greenhouse gases, continues to rise with the increase in fossil fuel consumption. In order to mitigate global warming the amount of CO2 discharge to the atmosphere must be reduced. Carbon dioxide capture and storage (CCS) technology is now regarded as one of the most promising options. To complete the carbon cycle in a CCS system, a huge amount of captured CO2 from major point sources such as power plantsshould be transported for storage into the marine or ground geological structures. Since 2005, we have developed technologies for marine geological storage of CO2,including possible storage site surveys and basic design of CO2 transport and storage process. In this paper, the design parameters which will be useful to construct on-shore and off-shore CO2 transport systems are deduced and analyzed. To carry out this parametric study, we suggested variations in thedesign parameters such as flow rate, diameter, temperature and pressure, based on a hypothetical scenario. We also studied the fluid flow behavior and thermal characteristics in a pipeline transport system.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.472-472
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• 2011

탁도는 물의 상대적인 흐림 정도를 나타내는 척도로서 이는 빛이 물을 통과할 때 산란시키는 부유고형물질 때문에 발생한다. 토양침식에 의하여 지표수로 유입된 토사와 광물질은 하천의 수송 및 퇴적 과정을 거치며 이동한다. 이때 하상 퇴적물은 바닥으로부터 먹이를 찾는 유기체에 의해 뒤섞이며 입자들은 일정기간동안 물의 흐름에 의해 부유상태로 남아 있게 되고, 유입되는 영양소와 빛에 의하여 성장하는 조류 또한 탁도를 증가시키는 원인이 된다. 이러한 부유물질의 증가는 수중에 태양복사에너지 전달을 방해하여 수중생태계의 먹이사슬과 저서생물의 서식환경에 많은 영향을 미치고, 수표면 온도 또한 태양으로부터 열을 흡수하는 표면 근처의 부유물질에 의해 증가하여 용존산소의 양에도 영향을 미친다. 따라서 수체내 분포하고 있는 부유물질의 종류와 양 및 공간적 분포 파악은 수질문제와 재난 예방 및 생물의 서식환경 문제를 파악하고 해결하는 데 매우 중요하다. 그러나 부유물질에 부착되어 있는 영양소, 금속, 살충제 등은 물 순환 시스템을 통하여 끊임없이 운반되고 상류유역의 흐름 조건에 따라 시공간적으로 변화하기 때문에 이를 규명하는 것이 매우 어려운 실정이다. 이러한 문제를 해결하기 위하여 광역적인 탁수환경의 분석방법으로 원격탐사(Remote Sensing, 이후 RS) 기법을 이용한 방법이 제안되고 있다. 이미 선진국에서는 광역수계의 수질관리를 위해 RS 기법을 이용하여 신속하고 정확한 수질상태 파악을 시도하고 있으며, 우리나라에서도 KOMPSAT 발사를 계기로 RS 관련 기술이 비약적으로 진화하고 있다. 그러나 RS 데이터를 활용하는데 필수적인 분광학적 특성 규명에 대한 연구는 대부분 식생과 토양에 한정되어 있으며 수체에 대한 연구는 현장조사의 어려움으로 인하여 상당히 제한적인 수준이다. 따라서 본 연구에서는 탁도의 변화에 따른 분광반사 특성을 휴대용 분광복사계를 이용하여 규명하고, 이를 Landsat 위성영상에 적용하여 새만금 유역을 대상으로 완공 직후인 2006년부터 2010년까지의 탁수환경을 모니터링 하였다. 그 결과 새만금 유역 탁수환경을 정성적으로 확인할 수 있었으며, 이를 이용하여 탁수환경 연구에 RS 기법이 효과적임을 제시하고자 한다.

• Environmental and Resource Economics Review
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• v.21 no.2
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• pp.271-299
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• 2012

The relationship between environment and economic growth has been controversial for a long time. The cores of controversy are endogeneity problem and omitted variable bias. This paper tests EKC (Environmental Kuznets Curves) hypothesis by considering econometric issues and estimates the effects of energy mix on $CO_2$ emissions empirically and tests with time series during 1981~2008. By the results of this analysis, we convince EKC Hypothesis which the relationship between $CO_2$ emissions and economic growth is the inverted U-shaped and the national energy mix contributes significantly to GHG mitigation. We also find that the nuclear energy has the greatest contribution for $CO_2$ mitigation and the renewable energy does not seem to contribute little to the $CO_2$ mitigation because the proportion of renewable energy in Korea is negligible. In terms of final energy consumption, $CO_2$ increases and transportation sector is statistically and significantly associated.

• Journal of Life Science
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• v.12 no.2
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• pp.121-128
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• 2002

The object of this study was to investigate the effect of membrane fluidity of bellflower(Platycodon grandiflorum A. DC, ; PG) fractions in phosphatidylcholine(PC) liposomes, measured with high-sensitivity differential scanning calorimetry(DSC). We used dipalmitoylphosphatidylcholine(DPPC) bilayers which slake most stable liposomes among the other phosphatidylcholine. The sample PG was extracted and fractionated to five different types : butanol(PGMB), ethylacetate(PGMEA), ethylether(PGMEE), hexane (PGMH) and methanol(PGMM). Among five different solvent fractions, the PGMEE, PGMEA, PGMH and PGMM fractions markedly affected the thermotropic properties of DPPC liposomes, broadened and shifted the thermograms, and reduced the cooperative unit. It might be said that the incorporation of PGMEE, PGMEA and PGMH in DPPC liposomes were located in the hydrophobic core of DPPC bilayers and, PGMM and PGMB in the hydrophilic core of DPPC bilayers. These results suggest that certain substances in the PGMEE, PGMEA and PGMH fractions might have biologically significant effect on the membrane fluidity.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.1020-1025
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• 1995

The Schottky barrier hieght(SBH) of Au/n-Si(100) were investigated by current-voltage(I-V) and capacitance voltage(C-V) measurement within a temperature range of l00K∼300K. The values of SBH at room temperature obtained from these two measurements were (0.79${\pm}$0.02)eV. The SBH obtained from the C-V measurement was temperature independent, while that obtained from the I-V measurement decreased linearly with decreasing temperature. This indicates that the Schottky diode has deviated from the thermionic emission theory at low-temperature, Thus, other current transport processes were considered and the contribution of recombination current was dominant at low temperature. We found that it leads to a lower SBH value. Thus, the conflicating results between C-V and I-V measurement were explained, C-V measurement is believed to yield mare reliable SBH values in present study since it is not affected by the current transport uncertainties.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.83-89
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• 2003

A temperature- and pressure-reducing process is utilized to handle the spent fuel assembly in the post-irradiation examination facility. This process includes three separated unit processes. First one is the decontamination process to clean the spent fuel assembly casks. The second process is the temperature-reducing process to reduce the temperature elevated by decay process in the spent fuel assembly. The third process is the filtration process to remove insoluble particles existed in the casks using filters. Up-to-date technologies as well as practical theories related to the temperature- and pressure-reducing process is reviewed in this report. The test-operation process for various tests and the test results of the temperature- and pressure-reducing process for J-44 and K-23 spent fuel assemblies are also described in detail. This report must be effectively used for the normal operation of the facility with the awareness of unprecedented problems which could occur by continuing operation of the PIE facility.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.76-82
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• 2012

Biomass and coal are great potential energy sources for gasification process. These solids can be gasified to produce syngas and bio-oil which can be upgraded further to transportation fuel. Two biomass and three coals have been gasified with steam in a thermobalance reactor under atmospheric pressure in order to evaluate their kinetic rate information The effects of gasification temperature ($600{\sim}850^{\circ}C$) and partial pressure of steam (30~90 kPa) on the gasification rate have been investigated. The three different types of gas-solids reaction models have been applied to the experimental data to compare their predictions of reaction behavior. The modified volumetric reaction model predicts the conversion data well, thus that model was used to evaluate kinetic parameters in this study. The gasification reactivity of five solids has been compared. The obtained activation energy of coal and biomass gasification were well in the reasonable range. The expression of apparent reaction rates for steam gasification of five solids have been proposed as basic information for the design of coal gasification processes.