• 한국토양환경학회지
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• 제1권1호
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• pp.81-88
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• 1996

토양과 토양용액의 경계면에서 토양내 흡착부위에 대해 경쟁적 이온이 존재할 때 카드늄의 흡착 현상을 연구하기 위하여, 토양의 Bt층으로부터 토양시료를 채취하여 토양의 물리화학적 특성을 분석하였다. 한편 Ethy-lone glycol monoethyl ether(EGME)와 질소가스를 가지고 각각의 토양의 특정표면적을 조사하였다. 토양층 내에서 토양입자와 반응성을 지닌 물질의 동태를 연구하는 일반적 지침으로, 물리화학적 특성이 완전히 다른 토양을 가지고 일반적인 등온흡착곡선을 취하였다. 단일 등온흡착곡선에서 보여 주었던 것처럼 물질간의 경쟁적흡착을 포함한 여러가지의 물리 화학적 요인들이 흡착에 영향을 미칠 것으로 추정된다. 한편 각각의 토양입자에 의한 카드늄 흡착의 정도는 사용된 토양과 용액의 회석 비율뿐만 아니라 각각의 토양의 표면적에 의존한다는 것을 알 수 있었다. 이러한 결과는 서로 다른 토양에서의 카드늄이 마그네시움과의 경쟁적 흡착에서도 적용되는 것을 알 수 있었다. 이러한 등온흡착곡선은 유해한 무기성분의 흡착과 동태 해석 뿐만 아니라 표준 배취흡착과정을 연구개발하는데 복합 요인으로 작용한다는 것을 증명하기 위한 예로서 사용할 수 있다.

• 한국항공우주학회지
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• 제47권11호
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• pp.803-811
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• 2019

물로켓은 가압된 기체와 액체(물)를 추진제로 이용하는 비화학식 로켓이다. 물로켓은 우주발사체로 사용되는 액체 추진제 로켓과 많은 공학적 공통점을 가지므로 로켓 공학 모델로써의 교구로 활용할 가치가 충분하다. 이를 위하여 본 논문에서는 물로켓의 발달사를 간략히 살펴보고 청소년용 물로켓, 상용 물로켓, 동호인들의 물로켓을 살펴봄으로써, 공학 교구로써 물로켓의 활용 가능성을 살펴보았다. 마지막으로 현행 물로켓 경연대회들의 한계를 살펴봄으로써, 물로켓에 대한 인식의 변화를 유도할 경연 방식의 개선방향을 제시한다.

• 유기물자원화
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• 제16권3호
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• pp.75-82
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• 2008

상향류 혐기성 슬러지 블랭킷 반응조을 이용한 프로피온산의 처리시 고농도 황산염의 영향을 조사하였다. 반응조의 평균 유기물 부하와 수리학적 체류시간은 $1.2kg \;COD/m^3{\cdot}d$와 1.6일로 유지하였다. 황산염이 없는 조건에서 UASB 반응조의 경우 95%의 COD 제거율을 보였으며 황산염이 $2,000mgSO_4^{2-}/L$로 존재하는 경우 용존 황화물의 영향으로 COD 제거율이 83%로 감소하였다. 메탄 생성균과 황산염 환원균의 경쟁관계를 평가하기 위하여 미생물의 상호작용에 관해 조사하였다. $COD/SO_4^{2-}$ 비가 1인 경우 이용 가능한 전자 수용체의 평균 58%가 메탄 생성균에 의해 이용되며 나머지가 황산염 환원균에 의해 사용되었다. 초산과 프로피온산을 기질로 이용한 비메탄 활성도의 경우 미생물이 기질에 적응함에 따라 증가하였다.

• 대한환경공학회지
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• 제28권10호
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• pp.1074-1081
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• 2006

질산성질소와 트리클로로에틸렌(TCE)을 동시에 제거하고자 이들을 화학적 생물학적으로 환원 및 수착시키는 반응매질로서 영가철과 피트(peat)를 이용하였다. 영가철의 수중산화로 발생된 수소가 질산성질소와 TCE를 환원시켜 두 물질이 제거하는데 TCE의 수착제거가 가능한 피트를 이용하고 그에 따른 혼합미생물의 생분해 및 전자전달의 효과를 이용하였다. 질산성질소의 경우 영가철과 피트혼합매질에서 제거효율이 우수하나 제거기작이 환원에 의존하므로 TCE가 공존시 전자에 대한 경쟁으로 그 제거효율이 감소하였으며 멸균처리한 피트를 사용한 실험군과의 결과비교로 탈질균의 작용을 알 수 있었다. TCE의 경우 영가철이 함유된 매질에서 제거효율이 높으며 질산염 공존이 영향을 미치지 못하였다. 생분해하는 혐기성 미생물군의 존재는 시스템에서 발생한 수소와 메탄가스 분석으로 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.610-613
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• 2009

New rod-disc liquid crystal (LC) molecule RD12 (12 is the number of carbon atoms between the rod and disc mesogenic liquid crystals) was synthesized via the chemical attachment of six cyanobiphenly calamitic mesogens linked to the triphenyl discotic mesogen with six alkyl chain linkage. Aligning characteristics associated with homogenous alignment is investigated at first and then field-dependent molecular reorientation under a vertical electric field is studied. Interestingly, they show abnormal slow molecular transition from initiate state (no electric field condition) to certain voltage. In this condition, we observe the molecular competition during reorientation. However, once a tilting direction of disk molecules are defined, the frustration is not observed anymore. The origin of this phenomenon is explained with a suggested model for the first time.

• 디지털융복합연구
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• 제11권10호
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• pp.189-201
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• 2013

정보통신기술의 급속한 발전으로 시장의 경계가 불분명해지고 있으며, 미래의 불확실성과 위험성 증가로 인해 글로벌 기업간 경쟁이 격화되고 있는 실정이다. 기업들은 이러한 경영환경의 변화에 적극적으로 대처하기 위한 방안으로 자사와 관련성이 높은 협력 기업만이 아닌 경쟁 관계에 있는 기업들과도 협력전략을 고려하고 있거나 이미 협력전략을 취하고 있는 실정이다. 이에 협력 전략은 기업의 생존뿐만 아니라 기업의 경쟁력 강화를 위한 중요한 요소라고 할 수 있으나 지금까지 협력전략과 관련한 대부분의 선행연구들은 협력 기업들의 특성이 협력 파트너 기업선정과 기업의 경영성과에 미치는 연구에만 초점을 맞추고 있다. 이에 본 연구에서는 선행연구와 델파이 조사를 통해 협력전략 구축의 동기와 목적 그리고 파트너 선택 시 중요요인들을 도출하였다. 또한 AHP 기법을 활용하여 대 중소기업 규모별, 전자 화학 산업별로 어떠한 차이를 보이는지에 대하여 분석을 하였다.

• 한국조경학회지
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• 제14권2호
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• pp.27-42
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• 1986

The vegetation structure in the Hoo - Won, Changduk Palace in Seoul was analysed on 10 sites sampled for understanding structure of natural vegetation. The main vegetational survey was conducted during July, 1985 and actual vegetaion and degree of natural vegetaion types were surveyed additionally. The result summarized of this research are as follows. 1) The physical - chemical conditions of soil showed middle class. This might be derived by short succession period from Pine forest to decidious broadleaf forest and artificial impact by human intervention. 2) When considering dominance species by crown story, Quercus aliena was a dominant species over all site and Castanea crenata, Prunus sargentii and Quercus variabilis appeared as a dominant species locally at upper story. Styrax story and Rhododendron mucronulatum, Styrax japonica, Stephanandra incisa and Lespedeza spp. at lower story. 3) The distances kept by trees per crown story are as follows. The mean distances between trees were 4.5-5.5m at upper story, 2.8-3.3m at middle story. On the other hand, the mean distances between dominant species were 6-8m at upper story, 5-9m at middle story. 4) The vegetation in this area was not developed yet into dominant species community according to the similarity analysis. The natural vegetation was dominated by Quercus spp. especially Quercus aliena according to the analysis of species diversity, relative dominance by story and DBH class. On the orther hand, succession to climax stage dominated by shade tolerent species will take a long time due to little appearance of shade tolerence species by previous heavy artificial impacts on understory species. 5) Quercus forest took possesion of 71.3%(27.37ha) of total forest area when considering the actual vegetation and especially Quercus aliena community covered 53.2%(15.21ha). Carpinus laxiflora community, one of the climax species in temperate zone, took possesion of 1.0%(0.3ha) and Pine densiflora was almost disappeared due to species competition. 6) According to the degree of natural vegetation types, the possession of degree of 6-9 was 60.6% and degree of 7-8, substitute vegetation, was 15.5%. The possesion of degree of 9 which consists of over 50 years old trees simliar to natural vegetaion was the highest, 43.1% in this area. Therefore continuous protection in this area of degree of 9 should be recommended.

• 산업융합연구
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• 제14권2호
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• pp.33-38
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• 2016

The Korean shipbuilding industry, which started in the 1970s with the advance of three shipbuilding companies, has been ranked as the world's largest and most successful model of the heavy and heavy chemical industry in the world since the 1990s, and has become a driving force for Korea's economic growth for several decades, including job creation and trade surplus. The domestic shipbuilding industry has won a lot of orders in favorable market environment, expanded facilities and manpower, built many ships and delivered them to shipowners, earning a lot of foreign currency and creating a 'successful myth.' However, when the global economic crisis broke out in 2008, shipbuilding in Chosun was stagnant and shipbuilding orders sharply decreased.As the facility and manpower increased in the boom period, the economy and the facilities become overcrowded as a result of the crisis, signs of a crisis in 2013 begin to appear. In 2015, three major Korean shipbuilders lost more than 6 trillion won in operating losses. Now, Korea's shipbuilding industry is facing a crisis such as massive insolvency and restructuring. Would not it have been possible to prevent the loss and restructuring of a trillion won if we recognized the recession of the global economy and understood the appropriate timing of technological innovation and prepared countermeasures against the crisis? Therefore, we analyze trends and trends of global shipbuilding industry such as Europe, China, and Japan in the competition structure of the shipbuilding industry and identify the problems of our shipbuilding industry and suggest suggestions.

• Geomechanics and Engineering
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• 제17권5호
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• pp.485-496
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• 2019

Sealing of leakage in waterfront or water-retaining structures is one of the major issues in geotechnical engineering practices. With demands for biological methods as sustainable ground improvement techniques, bioclogging, defined as the reduction in hydraulic conductivity of soils caused by microbial activities, has been considered as an alternative to the chemical grout techniques for its economic advantages and eco-friendliness of microbial by-products. This study investigated the feasibility of bioaugmentation and biostimulation methods to induce fermentation-based bioclogging effect in coarse sands. In the bioaugmentation experiments, effects of various parameters and conditions, including grain size, pH, and biogenic gas generation, on hydraulic conductivity reduction were examined through a series of column experiments while Leuconostoc mesenteroides, which produce an insoluble biopolymer called dextran, was used as the model bacteria. The column test results demonstrate that the accumulation of bacterial biopolymer can readily reduce the hydraulic conductivity by three-to-four orders of magnitudes or by 99.9-99.99% in well-controlled environments. In the biostimulation experiments, two inoculums of indigenous soil bacteria sampled from waterfront embankments were prepared and their bioclogging efficiency was examined. With one inoculum containing species capable of fermentation and biopolymer production, the hydraulic conductivity reduction by two orders of magnitude was achieved, however, no clogging was found with the other inoculum. This implies that presence of indigenous species capable of biopolymer production and their population, if any, play a key role in causing bioclogging, because of competition with other indigenous bacteria. The presented results provide fundamental insights into the bacterial biopolymer formation mechanism, its effect on soil permeability, and potential of engineering bacterial clogging in subsurface.

• 천문학회지
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• 제54권1호
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• pp.9-16
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• 2021

The Ozone Dynamics Investigation Nano-Satellite (ODIN) is a CubeSat design proposed by Chungnam National University as contribution to the CubeSat Competition 2019 sponsored by the Korean Aerospace Research Institute (KARI). The main objectives of ODIN are (1) to observe the polar ozone column density (latitude range of 60° to 80° in both hemispheres) and (2) to investigate the chemical dynamics between stratospheric ozone and ozone depleting substances (ODSs) through spectroscopy of the terrestrial atmosphere. For the operation of ODIN, a highly efficient power system designed for the specific orbit is required. We present the conceptual structural design of ODIN and an analysis of power generation in a sun synchronous orbit (SSO) using two different configurations of 3U solar panels (a deployed model and a non-deployed model). The deployed solar panel model generates 189.7 W through one day which consists of 14 orbit cycles, while the non-deployed solar panel model generates 152.6 W. Both models generate enough power for ODIN and the calculation suggests that the deployed solar panel model can generate slightly more power than the non-deployed solar panel model in a single orbit cycle. We eventually selected the non-deployed solar panel model for our design because of its robustness against vibration during the launch sequence and the capability of stable power generation through a whole day cycle.