• 한국광학회지
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• 제15권5호
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• pp.443-448
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• 2004

국제단위계 중의 하나인 칸델라 눈금을 두 개의 광도계를 사용하여 실현하였다. 광도계의 분광감응도는 광출력을 전기출력으로 치환하여 측정하는 극저온 절대복사계에 소급하여 측정하였다. 광도계 외부에 설치된 정밀 개구는 다이아몬드 회전가공기로 가공하였으며 그 면적은 불확도 0.05%(k = 1) 이내로 측정하였다. 이 광도계를 사용하여 광도 벤치 위에서 1 kW FEL 전구로 칸델라 단위를 실현할 때 불확도를 분광감응도, 감응도의 공간 균일도, 개구 면적, FEL 전구의 색온도와 위치 재현성을 고려하여 평가한 결과 0.25%(k = 1)를 얻었다. 실현한 눈금의 유효성을 확인하기 위하여 미국 NIST의 눈금과 비교한 결과 0.1% 이내에서 일치하였다.

• Journal of Microbiology and Biotechnology
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• 제23권5호
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• pp.689-698
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• 2013

The production and characterization of an active recombinant N-acetylgalactosamine-6-sulfate sulfatase (GALNS) in Escherichia coli BL21(DE3) has been previously reported. In this study, the effect of the signal peptide (SP), inducer concentration, process scale, and operational mode (batch and semi-continuous) on GALNS production were evaluated. When native SP was presented, higher enzyme activity levels were observed in both soluble and inclusion bodies fractions, and its removal had a significant impact on enzyme activation. At shake scale, the optimal IPTG concentrations were 0.5 and 1.5 mM for the strains with and without SP, respectively, whereas at bench scale, the highest enzyme activities were observed with 1.5 mM IPTG for both strains. Noteworthy, enzyme activity in the culture media was only detected when SP was presented and the culture was carried out under semi-continuous mode. We showed for the first time that the mechanism that in prokaryotes recognizes the SP to mediate sulfatase activation can also recognize a eukaryotic SP, favoring the activation of the enzyme, and could also favor the secretion of the recombinant protein. These results offer significant information for scaling-up the production of human sulfatases in E. coli.

• 한국조경학회지
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• 제45권1호
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• pp.35-51
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• 2017

가로정원은 서울시 가로환경 개선 사업의 일환으로, 보행자들에게 심미적 만족과 심리적 안정감을 제공하기 위한 휴식공간으로 설치되었다. 본 연구에서는 실제 가로정원이 이용자의 심리적 향상을 돕는지 고찰하기 위해, 가로정원과 이에 상응하는 비교대상지를 선정하여 설문조사를 실시하고, 결과를 비교하였다. 서울시에 위치한 총 9개의 가로정원 중 강남대로, 디지털로, 테헤란로에 설치된 가로정원을 대상지로 선택하였으며, 비교대상지로는 동일 대로상에 위치하며 물리적 환경이 유사하나 가로정원 사업이 시행되지 않은 3개의 장소를 선정하였다. 설문은 주의회복이론(Attention Restoration Theory: ART)을 근거, '매력감(Fascination), '벗어남(Being away)', '짜임새(Coherence)', '규모(Scope)'를 중심으로 구성된 회복환경지각척도-11(Perceived Restorativeness Scale-11) 질문과, 심리적 회복을 유도한 설계 요소를 묻는 질문으로 구성하였고, 요인분석, 신뢰도 분석, 독립표본 t-검정을 이용하여 분석하였다. 분석 결과, 가로정원은 이용자들의 심리적 회복에 비교적 긍정적 효과를 미치며, 특히 이용자들에게 매력감과 흥미로움을 부여한다고 나타났다. 그러나 가로정원은 이용자들에게 고단한 현실에서 벗어나는 듯한 느낌을 주지 못하여 심리적 향상효과의 한계를 드러냈다. 심리적 회복효과를 유도한 가로정원의 물리적 요소는 나무벤치, 나무, 꽃으로 나타나, 자연적인 요소가 인공적 요소보다 심리적 회복에 긍정적 영향을 준다는 심리회복 이론에 부합하였다. 본 연구의 결과는 향후 가로정원 사업을 추진함에 있어 계획 및 설계 가이드라인 개발에 기여할 것으로 기대된다.

• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.143-165
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• 2016

COP21에서 채택된 파리협정에서 명시한 지구 대기온도 $2^{\circ}C$ 이하 상승억제 목표를 달성하기 위해서는 현재 각 당사국이 제출한 감축 목표치로만은 부족한 상황이다. 이에 따라 향후 감축목표를 상향하기 위한 작업이 이루어질 것이다. $CO_2$ 배출량을 줄이기 위한 여러 수단 중 이산화탄소 포집 및 저장(CCS: Carbon Capture and Storage)은 필수 옵션으로 현재 전세계에서 대규모 실증이 진행되고 있다. 실증 단계에 있는 1세대 기술의 경우 높은 포집비용 및 발전원가 상승으로 정책적 뒷받침 없이는 시장보급이 어려운 실정이다. 이에 비용을 저감하기 위한 2세대, 3세대 혁신 포집기술들이 개발되고 있으며 2세대 기술들은 파일럿 규모로, 3세대 기술들은 벤치규모로 연구되고 있다. 본 리뷰 논문에서는 전세계 대규모 CCS 실증 사업 현황을 살펴보고, 2세대, 3세대 포집기술에 대해 연소전, 연소후, 신연소기술로 구분하고 습식 포집기술, 건식 포집기술, 분리막 기술, 산소연소기술의 세부 기술개발 내용에 대한 현재까지의 기술개발 결과를 요약정리하였다.

• 청정기술
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• 제28권2호
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• pp.163-173
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• 2022

지구 온난화를 완화시키고 석유고갈 문제를 피할 수 있는 수단의 하나로서 바이오 연료에 대한 많은 연구 개발이 지금까지 30년 넘게 이루어졌다. 하지만 일부 1세대 및 2세대 바이오 연료의 제한적인 보급이 이루어졌을 뿐, 광범위한 바이오 연료의 보급은 아직도 요원하다. 비교적 최근에 연구가 시작된 해조류 바이오매스 유래 3세대 바이오는 경우 많은 장점을 가지고 있음에도 불구하고 상업 규모의 해조류 바이오 리파이너리의 보급은 아직도 멀기만 하다. 이 총설에서는 광범위한 문헌조사와 10년 넘게 해조류 바이오 리파이너리의 타당성 연구를 수행한 저자의 경험을 토대로 해조류와 해조류의 양식부터 최종 제품인 바이오 연료 생산까지 가치사슬 전반에 걸쳐 해조류 바이오 리파이너리가 가진 장점과 단점을 살펴보고자 한다. 이 관점에서 문헌조사는 (1) 전 세계 해조류 생산 및 연구 개발 현황, (2) 실험실 규모 실험에 기초한 해조류로부터 바이오 연료 생산을 위한 전환 기술, 그리고 (3) 대규모 해조류 바이오 리파이너리 타당성 연구를 포함할 것이다. 그리고 해조류 바이오 연료 상업화에 예상되는 주요 문제점을 확인하고 마지막으로 현재의 해조류 바이오 리파이너리 기술 현황과 유망한 미래 전망에 대한 저자의 견해가 정리될 것이다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제17권6호
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• pp.52-58
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• 2012

Capillary fringe divides the groundwater and the vadose zone controlling the diffusive mass transfer of contaminants and gases. The thickness of capillary fringe is of great importance for the rate of contaminant mass transfer across the capillary fringe. Application of surface active chemicals including surfactants and alcohol-based products into the subsurface environment changes the surface tension of the aqueous phase, which in turn, affects the thickness of the capillary fringe. In this study, a bench-scale model was used to assess the quantitative relationship between the surface tension and the thickness of the capillary fringe. An anionic surfactant (Sodium dodecylbenzene sulfonate, SDBS) and an aqueous solution of ethanol were used to control the surface tension of the groundwater. It was found that the thickness of the capillary fringe is directly proportional to the surface tension. The air entry pressures measured by the Tempe Pressure Cell at different surface tensions using SDBS (200 mg/L) and ethanol (20%, v/v) solutions were in good agreement with the thicknesses of the capillary fringe measured by the model. A simple method to correct the conventional Brooks-Corey model for estimating the air entry pressure was also presented.

• Steel and Composite Structures
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• 제25권3호
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• pp.361-374
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• 2017

In this study, the influences of triaxial magnetic field on the wave propagation behavior of anisotropic nanoplates are studied. In order to include small scale effects, nonlocal strain gradient theory has been implemented. To study the nanoplate as a continuum model, the three-dimensional elasticity theory is adopted in Cartesian coordinate. In our study, all the elastic constants are considered and assumed to be the functions of (x, y, z), so all kind of anisotropic structures such as hexagonal and trigonal materials can be modeled, too. Moreover, all types of functionally graded structures can be investigated. eigenvalue method is employed and analytical solutions for the wave propagation are obtained. To justify our methodology, our results for the wave propagation of isotropic nanoplates are compared with the results available in the literature and great agreement is achieved. Five different types of anisotropic structures are investigated in present paper and then the influences of wave number, material properties, nonlocal and gradient parameter and uniaxial, biaxial and triaxial magnetic field on the wave propagation analysis of anisotropic nanoplates are presented. From the best knowledge of authors, it is the first time that three-dimensional elasticity theory and nonlocal strain gradient theory are used together with no approximation to derive the governing equations. Moreover, up to now, the effects of triaxial magnetic field have not been studied with considering size effects in nanoplates. According to the lack of any common approximations in the displacement field or in elastic constant, present theory has the potential to be used as a bench mark for future works.

• 한국조경학회지
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• 제38권5_2호
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• pp.186-193
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• 2010

The purpose of this study was to survey the citizens for their satisfaction with the outdoor landscape lighting in Gyeongju Historic Areas registered as UNESCO World Cultural Heritage in November 2000 and thereupon, provide for some basic data useful to the design of the outdoor landscape lighting for the cultural properties. As a result of examining the conditions of the outdoor landscape lighting in Wolseong Zone of Anapji, Banwolseong, Dongbu Sajeokji, Cheomseongdae and Gyerim, there were found 391 lighting fixtures of 12 types in Anapji, 138 lightings of 4 types in Banwolseong, 38 lightings of 6 types in Cheomseongdae, 28 lightings of 3 types in Dongbu Sajeokji and 54 lightings of 5 types in Gyerim. As a result of analyzing citizens' satisfaction with the outdoor landscape lighting, it was found that citizens were satisfied more or less with the nightscape image changed by the outdoor landscape lighting; their satisfaction scored 3.836 on average for Anapji on a 5-point Likert type scale, 3.516 for Banwolseong, 3.446 for Dongbu Sajeokji, 3.650 for Cheomseongdae and 3.479 for Gyerim. However, citizens' satisfaction with the originality of the nightscape was generally low: 3.055 for Anapji, 2.914 for Cheomseongdae, 2.877 for Banwolseong, 2.847 for Gyerim and 2.665 for Dongbu Sajeokji. On the other hand, since most of the lighting fixtures were installed as inserted lights or floodlights, the color tones of light source were relatively highly distinctive, but the peripheral spaces around the cultural properties were rather dark, which means that citizens were feeling inconvenient more or less for using the amenities such as bench or waste box. All in all, their satisfaction with the outdoor landscape at the sample zone at night scored 2.981, lower than the normal level.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.17-17
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• 2017

In electric agricultural machine the gearhead is needed to convert the high speed low torque rotation motion generated by DC motor to lower speed high torque motion used by the vehicle. The gearhead consist of several spur gears works as reduction gears. Spur gear have straight tooth and are parallel to the axis of the wheel. Spur gears are the most easily visualized gears that transmit motion between two parallel shafts and easy to produce. The modeling and simulation of spur gears in DC motor gearhead is important to predict the actual motion behavior. A pair of spur gear tooth in action is generally subjected to two types of cyclic stress: contact stress and bending stress including bending fatigue. The stress may not attain their maximum values at the same point of contact fatigue. These types of failure can be minimized by analysis of the problem during the design stage and creating proper tooth surface profile with proper manufacturing methods. To improve its life expectation in this study modal and stress analysis of gearhead is simulated using ansys work bench software based on finite element method (FEM). The modal analysis was done to understand gearhead deformation behaviour when vibration occurs. FEM static stress analysis is also simulated on gearhead to simulate the gear teeth bending stress and contact stress behavior. This methodology serves as an approach for gearhead design evaluation, and the study of gear stress behavior in DC motor gearhead which is needed in the small workshop scale industries.

• 한국미생물·생명공학회지
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• 제25권1호
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• pp.89-95
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• 1997

The current processer of the textile wastewater treatment are mostly consisted of a combination of a physico-chemical and a biological treatment. The overall efficiency of these processes is, however, assessed to be fairly low. It is even worse during the summer season when temperature of the wastewater rises above 40$\circ $C. Therefore, a feasible process of the textile wastewater treatment which can work efficiently at higher temperatures was investigated in this work. We used a bench scale reactor consisted of one 4 liter anaerobic and one 8 liter aerobic tank, and the thermophilic symbiotic PVA degraders, Pasteruella hemolytica KMG1 and Pseudomonas sp. KMG6 that had been isolated in our laboratory. In the preliminary flask experiments, we observed that the thermophilic symbiotic PVA degraders could not grow in the wastewater substrate. Then, we isolated the mutant strains by acclimating the KMG1and KMG6 strains to the wastewater medium. The mutant symbionts (KMG1-1 and KMG6-1) were isolated through 6 times successive transfers into the fresh wastewater medium after 5 days culture for each. The mutant strains obtained grew well in the mixed medium composed of 75% wastewater and 25% synthetic medium, and supplemented with 0.5% PVA as a sole carbon source. During the culture for 14 days at pH 7.0 and 40$\CIRC $C, the bacteria assimilated about 89% of the added PVA. The symbionts degraded equally well all the PVA substrates of different molecular weight (nd=500~30000). In contrast to the flask experiments, in the reactor system the mutant strains showed very low levels of the PVA and COD removal rates. However, the new reactor system with an additional aerobic tank attained 82% removal rate of COD, 94% of PVA degradation and 71% of color index under the conditions of 5% inoculm on the tank 2, incubation temperature of 40$\circ $C, dissolved oxygen level of 2~3 mg/l and retention time of 30 hours. This result ensures that the process described above could be an efficient and feasible treatment for the PVA contained textile wastewater at higher temperatures.