• 대한지리학회지
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• 제33권3호
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• pp.377-394
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• 1998

화분분석이나 연륜분석 같은 전통적인 고기후 연구 방법론이 이용되기 어려운 육상 환경하에서. 토양내 자성 특성은 제4기 기후 연구의 수단중 가장 좋은 수단 중 하나가 되었다. 본 연구에서는 미국 중부 평원지역에서 제4기말 위스컨신 빙하기와 흘로세에 퇴적된 고토양/뢰스 층에서 자성변수들의 층서에 따른 대자율과 잔류자기의 특성을 연구하였다. 고토양에는 자성물질 집적이 많고. 잔류자기의 특성도 토양화의 영향으로 크기가 작은 2차 자성광물의 존재를 보이는데 비하여, 빙하기의 풍화정도가 약한 뢰스에서는 집적량이 적고 입자가 큰 1차 광물이 많은 것으로 나타났다. 자성변수들은 기후에 민감한 것으로 알려진 다른 생물학적 지표들과의 높은 상관관계를 통해 기후변화를 잘 반영하는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1197-1202
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• 2005

The Ln(III) complexes with picrate ligand, $[Sm(Pic)_2(H_2O)_6]Pic{\cdot}6H_2O$, 1, and $[Ho(Pic)(H_2O)_7](Pic)_2{\cdot}3H_2O$, 2, have been synthesized and their crystal structures are analyzed by X-ray diffraction methods. Complex 1, crystallizes in the monoclinic $P2_1/n$ space group and complex 2 in the triclinic P-1 space group. In complex 1, two picrate ligands coordinate to the Sm(III) ion, one of them in the bidentate fashion. There are one picrate anion and six water molecules in the crystal lattice. The nine-coordinated Sm(III) ion forms a slightly distorted tricapped trigonal prism. In complex 2, only one picrate ligand coordinates to the metal ion as a monodentate. There are two picrate anions and three water molecules in the crystal lattice. The eight-coordinated Ho(III) ion forms a distorted bicapped trigonal prism. Based on the results of the TG-DTG and DSC thermal analysis, it was analyzed that the lanthanide picrate complexes 1 and 2 are thermally decomposed in three distinctive stages, the dehydration, the picrate decomposition, and the formation of the metal oxide.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3629-3633
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• 2011

The effect of a dense $TiO_2$ blocking layer prepared using the sol-gel method on the performance of dye-sensitized solar cells was studied. The blocking layer formed directly on the working electrode, separated it from the electrolyte, and prevented the back transfer of electrons from the electrode to the electrolyte. The dyesensitized solar cells were prepared with a working electrode of fluorine-doped tin oxide glass coated with a blocking layer of dense $TiO_2$, a dye-attached mesoporous $TiO_2$ film, and a nano-gel electrolyte, and a counter electrode of Pt-deposited FTO glass. The gel processing conditions and heat treatment temperature for blocking layer formation affected the morphology and performance of the cells, and their optimal values were determined. The introduction of the blocking layer increased the conversion efficiency of the cell by 7.37% for the cell without a blocking layer to 8.55% for the cell with a dense $TiO_2$ blocking layer, under standard illumination conditions. The short-circuit current density ($J_{sc}$) and open-circuit voltage ($V_{oc}$) also were increased by the addition of a dense $TiO_2$ blocking layer.

• 대한기계학회논문집B
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• 제35권10호
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• pp.1025-1031
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• 2011

자발화 특성은 디젤 및 PCCI 엔진의 설계에서 중요한 인자이다. 특히, 디젤분무화염은 자발화현상에 의해서 형성되어 노즐에서 부상된다. 노즐과 부상화염 사이의 영역에서 분무된 디젤의 중앙으로 주위 공기의 유입이 발생하기 때문에, 그 부상된 화염은 매연 생성에 영향을 준다. 본 연구에서 간단한 모델로써 동축류 제트를 적용하였고, 점화지연시간에 대한 자발화 과정에서 발생하는 열손실의 영향을 확인하였다. 메탄($CH_4$), 에틸렌($C_2H_4$), 에탄($C_2H_6$), 프로핀($C_3H_6$), 프로판($C_3H_8$), 및 노말 부탄(n-$C_4H_{10}$)의 연료들을 고온의 공기로 분사하였으며 자발화된 부상화염의 높이를 측정하였다. 그 결과로 자발화된 부상화염의 높이와 열손실을 고려한 점화지연시간과의 상관관계를 결정하였다.

• Journal of Ginseng Research
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• 제41권3호
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• pp.298-306
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• 2017

Background: Compound K (CK) is a bioactive derivative of ginsenoside Rb1 in Panax ginseng (Korean ginseng). Its biological and pharmacological activities have been studied in various disease conditions, although its immunomodulatory role in innate immunity mediated by monocytes/macrophages has been poorly understood. In this study, we aimed to elucidate the regulatory role of CK on cellular events mediated by monocytes and macrophages in innate immune responses. Methods: The immunomodulatory role of CK was explored by various immunoassays including cell-cell adhesion, fibronectin adhesion, cell migration, phagocytic uptake, costimulatory molecules, reactive oxygen species production, luciferase activity, and by the measurement of mRNA levels of proinflammatory genes. Results: Compound K induced cell cluster formation through cell-cell adhesion, cell migration, and phagocytic activity, but it suppressed cell-tissue interactions in U937 and RAW264.7 cells. Compound K also upregulated the surface expression of the cell adhesion molecule cluster of differentiation (CD) 43 (CD43) and costimulatory molecules CD69, CD80, and CD86, but it downregulated the expression of monocyte differentiation marker CD82 in RAW264.7 cells. Moreover, CK induced the release of reactive oxygen species and induced messenger RNA expression of proinflammatory genes, inducible nitric oxide synthase, and tumor necrosis factor-alpha by enhancing the nuclear translocation and transcriptional activities of nuclear factor kappa-B and activator protein-1. Conclusion: Our results suggest that CK has an immunomodulatory role in innate immune responses through regulating various cellular events mediated by monocytes and macrophages.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.231-237
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• 2018

In this study, two important requirements for the home production of a robot to detect and remove improvised explosive devices (IEDs) are presented in terms of the total cost for robot system development and the performance improvement of the mine detection technology. Firstly, cost analyses were performed in order to provide a reasonable solution following an engineering estimate method. As a result, the total cost for a mass production system without the mine detection system was estimated to be approximately 396 million won. For the case including the mine detection system, the total cost was estimated to be approximately 411 million won, in which labor costs and overhead charges were slightly increased and the material costs for the mine detection system were negligible. Secondly, a method for fabricating the carbon nanotube (CNT) based gas detection sensor was studied. The detection electrodes were formed by a photolithography process using a photosensitive CNT paste. As a result, this method was shown to be a scalable and expandable technology for producing excellent mine detection sensors. In particular, it was found that surface treatments by using adhesive taping or ion beam bombardment methods are effective for exposing the CNTs to the ambient air environment. Fowler-Nordheim (F-N) plots were obtained from the electron-emission characteristics of the surface treated CNT paste. The F-N plot suggests that sufficient electrons are available for transport between CNT surfaces and chemical molecules, which will make an effective chemiresistive sensor for the advanced IED detection system.

• 자원환경지질
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• 제25권2호
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• pp.167-177
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• 1992

The gravity measurement has been conducted at 53 and 34 stations with an interval of 1~1.5 km along the national roads of about 47 km and 34 km running from Duksungri to Yangpori and from Angangri to Byungpori, Kyungsangbookdo, respectively. The subsurface geology and geologic structure of Tertiary Pohang and Janggi basins along two survey lines are interpreted quantitatively by applying Fourier series and Talwani methods for Bouguer gravity anomaly. The depths of Conrad discontinuity vary from 11.8 to 12.5 km and 11.5 to 13.2 km along the survey lines between Duksungri and Yangpori, and Angangri and Byungpori, respectively. The depths of pre-Cambrian Gneiss complex underneath Kyungsang Supergroup vary from 3.8 to 4.2 km and 3.8 to 4.6 km along the survey lines between Duksungri and Yangpori, and Angangri and Byungpori, respectively. Massive granite bodies which are not exposed along the survey line between Duksungri and Yangpori are distributed on a large scale at the subsurface between Duksungri and Ochun, and Daegokri and Yangpori. Along the survey line between Angangri and Byungpori, it is exposed at Angangri, and extends underneath Chungrimdong, Pohang city. Andesite is distributed on a small scale underneath Pohang city and Ochun. The thicknesses of Tertiary Yonil and Janggi Groups are 0.2~0.9 km and 0.1~0.5 km, respectively. The Tuffaceous rocks which are the lowest formation of Tertiary sedimentary rocks are distributed with the thickness of 0.2 km at the surface and between Kyungsang Supergroup and Yonil or Janggi Groups. The Yonil and Janggi Groups are in fault contact by a fault running through Ochun and Chungrimdong, Pohang city. Two other faults are newly found near Heunghae-eup and Hyungsan river.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.732-737
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• 2008

e러닝이 새로운 교육 형태로 인식되면서 학습자들의 교육 효과를 극대화시키기 위해 학습의 전반적인 활동을 관리해주는 학습관리시스템(Learning Management System)의 개발도 활발히 이루어지고 있다. 일반적으로 학습관리시스템은 온라인상에서 수강신청부터 학습은 물론 학습자의 학습기록 및 추적, 성적 평가 등의 기능을 포함하고 있다. 그러나 학습자들이 주도적으로 학습을 계획하고 평가 기준을 세우며 이를 통해 동료 학습자들과 협력할 수 있는 시스템은 미비한 실정이다. 또한 e러닝이 새로운 교육 패러다임으로 인식되고는 있으나 여전히 전통적인 면대면 수업 방식에서의 상호작용 효과는 기대하기 어려운 실정이다. 이 논문에서는 온라인과 오프라인 환경을 모두 지원하는 블렌디드 러닝 기반의 학습관리시스템에서 학습자들이 주도적으로 그룹형성 및 학습계획, 상호평가 등 자발적인 참여를 유도할 수 있는 협력학습 지원 모듈을 제안하여 기존의 LMS 기능에 토론 및 팀프로젝트 등을 원활히 할 수 있어 효과적인 협력학습 활동을 기대할 수 있다.

• 한국산학기술학회논문지
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• 제14권9호
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• pp.4227-4239
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• 2013

본 연구는 지식이전 과정에서 조직 구성원의 사회네트워크 특성과 지식이전 성과 간 관계를 실증 분석하였다. 특히 사회적 구조와 사회적 관계라는 두 관계를 동시에 고려하여 지식이전에 관한 새로운 관점의 모형을 제시하였다. 본 연구모형의 주요 구성개념인 구성원간의 사회적 관계 강도, 지식이전, 성과 그리고 지식특성을 통합하여 실증 분석하였다. 이를 위하여 국내 기업 및 관공서 총 52개 조직의 296개의 설문을 최종 연구모형 분석에 이용, 분석한 결과는 다음과 같다. 첫째, 사회적 관계의 강도는 지식이전에 유의한 영향을 미치는 것으로 검증되었으며, 이때 내집단의 관계강도가 외집단 관계강도보다 지식이전에 보다 유의한 영향력을 미치는 것으로 나타났다. 둘째, 지식이전은 모든 성과(개인, 팀, 조직)에 긍정적 영향을 미치는 것으로 파악되었다. 셋째, 응용지는 내집단 관계강도와 지식이전의 간의 관계를 강화하는 것으로 나타나, 응용지의 조절효과를 확인하였다.

• Molecules and Cells
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• 제40권2호
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• pp.117-122
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• 2017

Despite the fact that porcine embryonic stem cells (ESCs) are a practical study tool, in vitro long-term maintenance of these cells is difficult in a two-dimensional (2D) microenvironment using cellular niche or extracellular matrix proteins. However, a three-dimensional (3D) microenvironment, similar to that enclosing the inner cell mass of the blastocyst, may improve in vitro maintenance of self-renewal. Accordingly, as a first step toward constructing a 3D microenvironment optimized to maintain porcine ESC self-renewal, we investigated different culture dimensions for porcine ICM-derived cells to enhance the maintenance of self-renewal. Porcine ICM-derived cells were cultured in agarose-based 3D hydrogel with self-renewal-friendly mechanics and in 2D culture plates with or without feeder cells. Subsequently, the effects of the 3D microenvironment on maintenance of self-renewal were identified by analyzing colony formation and morphology, alkaline phosphatase (AP) activity, and transcriptional and translational regulation of self-renewal-related genes. The 3D microenvironment using a 1.5% (w/v) agarose-based 3D hydrogel resulted in significantly more colonies with stereoscopic morphology, significantly improved AP activity, and increased protein expression of self-renewal-related genes compared to those in the 2D microenvironment. These results demonstrate that self-renewal of porcine ICM-derived cells can be maintained more effectively in a 3D microenvironment than in a 2D microenvironment. These results will help develop novel culture systems for ICM-derived cells derived from diverse species, which will contribute to stimulating basic and applicable studies related to ESCs.