• Smart Structures and Systems
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• 제12권1호
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• pp.41-54
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• 2013

Concrete is known as a heterogeneous product which is composed of complex chemical composition and reaction. The development of concrete thermal effect during early age is critical on its future structural health and long term durability. When cement is mixed with water, the exothermic chemical reaction generates hydration heat, which raises the temperature within the concrete. Consequently, cracking may occur if the concrete temperature rises too high or if there is a large temperature difference between the interior and the exterior of concrete structures during early age hydration. This paper describes the contribution of novel Fabry-Perot (FP) fiber optic temperature sensors to investigate the thermal effects of concrete hydration process. Concrete specimens were manufactured under various water-to-cement (w/c) ratios from 0.40 to 0.60. During the first 24 hours of concreting, two FP fiber optic temperature sensors were inserted into concrete specimens with the protection of copper tubing to monitor the surface and core temperature change. The experimental results revealed effects of w/c ratios on surface and core temperature developments during early age hydration, as well as demonstrating that FP fiber optic sensors are capable of capturing temperature variation in the concrete with reliable performance. Temperature profiles are used for calculating the apparent activation energy ($E_a$) and the heat of hydration (H(t)) of concrete, which can help us to better understand cement hydration.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.237-242
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• 2004

Recombinant human ferritin homopolymers (rHF and rLF) were successfully produced in the Saccharomyces cerevisiae Y2805, which was transformed with human ferritin H or L-chain genes, respectively. In order to characterize the molecular properties of the recombinant ferritins in relation to mineralization, the proteins were isolated and apoferritins were prepared. The apoferritins were reconstituted with 2000 Fe atoms per protein molecule under various experimental conditions (the concentration of the protein, the buffer concentration of the MOPS buffer, the total volume of the reaction and the reconstitution method). The structure and composition of the iron cores formed in the ferritins were examined using transmission electron microscopy. The recombinant ferritins behaved in a similar manner to other mammalian ferritins in accumulating iron in the core. Proteins of rHF and rLF showed varying reconstitution yields of 37-72% depending on the reaction conditions. In general, the rHF showed higher reconstitution yield than the rLF at the protein concentrations and the reaction volumes we examined. Iron cores with a similar mean particle size were obtained in the rHF, rLF and horse spleen ferritin reconstituted at a protein concentration of 1.0 mg/mL. Electron diffraction of all the three ferritins showed 2-3 diffuse lines, with d-spacings corresponding to those of the mineral ferrihydrite with a limited crystallinity.

• 자원환경지질
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• 제23권1호
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• pp.35-57
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• 1990

This study has been carried out on the Pegmatites, Naedeogri Granites, Nonggeori Granites and Metasedimentary rocks in the middle area of Taebaeksan region to investigate the geochemical properties and possibility of productivity. Pegmatites are characterized by metamorphosed anatectic pegmatite and differentiated magmatic pegmatite, and are mixed type of rare-element pegmatite and mica-bearing pegmatite by the classification of Ginsburg(1979). The petrological type of the igneous rocks is thought to be calcalkali, subalkaline and peralumious. According to chemical variations against D. I., differentiation trends from Naedeogri and Nonggeori Granites through non-mineralized pegmatites to mineralized pegmatites are supposed. From the relationship between oxided and $SiO_2$, pegmatites and Nonggeori Granite have shown similar tendencies and bulk composition of pegmatites and similar to metasedimentary rocks near the intrusives. By judging the correlations of trace elements, it is elucidated that pegmatites adjacent to Naedeogri and Nonggeori Granites have been originated in magma differentiation from these granites and the others have been differentiated by remelting or partial melting from metasedimentary rocks. $Sp_5$, $Sp_8$, and $Sp_9$ pegmatites are considered as productive rocks, and $Sp_4$, $Sp_6$, $Sp_7$, $Sp_{10}$, $Sp_{11}$, and $Sp_{12}$ pegmatites and granites are supposed to have a weak productivity, in terms of element ratios related with Sn mineralizations. Tourmalines in productive pegmatites are formed under the circumstance of Li-poor granitoids and associated with pegmatites, and the others are seemed to be originated in metapelites and metapsammites which are not coexisting with an Al-saturating phase. Three types of chemical zoning are noticed in tourmalines: (1) apparently homogeneous compositional patterns, (2) a continuous core-to-rim zoning and, (3) a discontinuous core-to-rim zoning. From results of EPMA of tourmalines, Al, Mg and Ca increase closer to rim, while Fe decreases.

• 한국통신학회논문지
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• 제35권5B호
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• pp.777-784
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• 2010

현대의 정보화 사회에서는 정보기술이 기업과 공공기관에 도입되면서 정보기술 전반을 관리해야 한다는 필요성이 대두되었고, 비즈니스 목표와 IT의 연계 필요성이 증대되고 함께 IT투자의 중복을 방지하고 ROI를 추구하는 조직들이 늘어났다. 이에 여러 선진 기업들이 IT 거버넌스라는 개념을 제창하였다. IT 거버넌스는 기업의 비즈니스와 IT에 영향을 미치는 구조적 결정인자들의 구조 및 동적양상을 나타내며, 비즈니스와 IT 관련 사내외 위원회 및 부서, 그리고 그들의 활동범위 및 연관관계를 나타내는 프레임워크, 조직도 및 프로세스 구성으로 표현이 된다. 이러한 외부적인 요인과 맞물려 현재 우리 군의 국방 비전과 목표를 달성하기 위한 국방 IT 거버넌스의 재확립은 필수적인 사항이 되었다. 본 논문에서는 국방 IT 거버넌스의 프레임워크를 구축하기 위한 핵심 추진전략에 대해서 기술하였다. 이러한 주장에 뒷받침하기 위해서 IT 거버넌스의 전반적인 내용을 기술하고 국내 외와 해외의 군 사례를 분석하여 보고 국방 IT 거버넌스의 프레임워크 구축을 위한 핵심 추진전략을 연구하였다.

• Journal of Welding and Joining
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• 제29권1호
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• pp.99-106
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• 2011

Joint strength between a solder ball and a pad on a substrate is one of the major factors which have effects on electronic device reliability. The effort to improve solder joint strength via surface cleaning, heat treatment and solder composition change have been in progress. This paper will discuss the method of solder ball joint strength improvement using LF hydrogen radical cleaning treatment and focus on the effects of surface treatment condition on the solder ball shear strength and interfacial reactions. In the joint without radical cleaning, voids were observed at the interface. However, the specimens cleaned by hydrogen-radical didn't have voids at the interface regardless of cleaning time. The shear strength between the solder ball and the pad was increased over 120%(about 800gf) when compared to that without the radical treatment (680gf) under the same reflow condition. Especially, at the specimen treated for 5minutes, ball shear strength was considerably increased over 150%(1150gf). Through the observation of fracture surface and cross-section microstructure, the increase of joint strength resulted from the change of fracture mode, that is, from the solder ball fracture to IMC/Ni(P) interfacial fracture. The other cases like radical treated specimen for 1, 3, 7, 9min. showed IMC/solder interfacial fracture rather than fracture in the solder ball.

• BMB Reports
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• 제34권4호
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• pp.365-370
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• 2001

We constructed a comparative expression system in order to produce recombinant human ferritin homo- and heteropolymers in Escherichia coli. Human ferritin H-(hfH) and L-chain (hfL) genes were expressed without amino acid changes under the control of a tac promoter. Ferritin heteropolymers of varying subunit composition were also produced by combining two different expression systems, a bicistronic expression system and a coplasmid expression system. As a result, recombinant H-chain ferritin and ferritin heteropolymers were catalytically active in forming iron core in vivo. In particular, the ferritin heteropolymer that is composed of 7% H-subunit and 93% L-subunit was capable of forming an iron core of the protein, while the L-chain ferritin homopolymer was inactive in vivo. This result indicates that the two H-subunits (i.e., 7% H-subunit content) are important to keep ferritin active in the cells. In addition, human ferritins were identified as the major iron binding proteins in the transformed cells. Also, the amount of iron bound to the recombinant ferritins was proportional to the H-subunit content in ferritin heteropolymers in vivo.

• 정보처리학회논문지D
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• 제13D권2호
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• pp.251-258
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• 2006

영역지향 소프트웨어 개발 방법론(Aspect-Oriented Software Development)은 소프트웨어의 성능을 향상시키고 유지보수에 많은 이점을 가지는 새로운 소프트웨어 개발 방법론이다. 또한 기존의 프로그래밍 언어가 제공하지 못하는 보안이나 결함 내성과 같은 부가기능에 대해 모듈화하는 방법을 제공하고 있다. 하지만 AOSD기반으로 소프트웨어를 개발하기 위해서는 Aspect를 지원하는 새로운 영역지향 프로그래밍 언어를 사용하거나 레거시 시스템에 Aspect를 적용할 경우에 소스코드의 재 컴파일등과 같은 문제점을 가지고 있다. 이에 본 논문에서는 레거시 시스템에 Aspect를 동적으로 결합할 수 있는 Connector를 제안하고 설계한다. 이를 위하여 Core와 Aspect가 가지는 오퍼레이션에 대한 정보와 XML로 기술된 pointcut정보를 이용한다. 또한 사례연구를 통하여 제안된 Connector를 사용하기 위해 새로운 영역지향 컴파일러가 필요 없고, 레거시 시스템의 수정도 발생하지 않음을 보여 그 유효성을 검증한다.

• Design & Manufacturing
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• 제13권4호
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• pp.45-50
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• 2019

The fourth industrial revolution calls for an integrated talent by improving working-level skills within the big framework of creativity and convergence. Therefore, university education focuses on solving the problem of practical ability education by improving employment ability. Based on this improvement in practical skills, this study is based on the field-based design curriculum of Capstone. Currently, the Capstone Design Course is being implemented at most universities, extending its scope to the fields of engineering, humanities, social studies and arts. However, there is a limit to the core concept of Capstone design education and capacity education developed in line with the foreign educational environment and applied directly to our nation's university education. In terms of overseas cases, the core focus is to develop practical, design, and prototype capabilities by forming a team among all grades and multidisciplinary institutions to support the capital and manpower of the industry. However, the nation's industrial linkage and curriculum have difficulties in carrying out multi-disciplinary education. In this study, students were asked to team up and solve the challenges that the industry needs based on the expertise acquired in the lower grade curriculum by applying majors and 3D printing through the first and second semester courses of the fourth grade to address these limitations. In addition, business skills for the process of creativity and leadership experience in our country through a suitable design capstone class to review the efficiency of education by applying a model. In order to achieve the purpose of Capstone design subject, the goal setting, class model composition, class model application, verification and evaluation, and final class model development procedures were carried out. Through this process, it will be used as a basic material for educating design class capstone design.

• 공업화학
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• 제8권6호
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• pp.881-885
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• 1997

본 연구에서는 유용성 염료인 sudan III를 이용하여 비이온 계면활성제인 GL-12와 범용 음이온 계면활성제인 linear laurylbenzene sulfonate(LAS) 또는 sodium polyoxyethylene(3) glycol lauryl ether sulfate (SLES) 혼합 용액의 가용화력에 대하여 조사하였다. 두 계면활성제 혼합계 (GL-12/LAS, GL-12/SLES)의 가용화력은 각각 계면활성제 혼합비에 크게 영향을 받았으며 GL-12의 함량이 증가할수록 가용화력도 증가 하였다. 용액의 가용화력에 NaCl이 미치는 영향으로부터 GL-12/LAS계에서는 solubilizate인 sudan III가 가용화 후 미셀내 palisade 층 근처에 위치하고 GL-12/SLES 혼합계에서는 solubilizate가 미셀의 core부근에 위치함을 알 수 있었고 이는 LAS와 SLES의 분자구조 차이에 기인한다.

• Journal of Electrochemical Science and Technology
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• 제1권1호
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• pp.31-38
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• 2010

In this study, we have demonstrated the fine structure effect of PdCo electrocatalyst on oxygen reduction reaction activity with different alloy composition and heat-treatment time. In order to identify the intrinsic factors for the electrocatalytic activity, various X-ray analyses were used, including inductively coupled plasma-atomic emission spectrometer, transmission electron microscopy, X-ray diffractometer, and X-ray Absorption Spectroscopy technique. In particular, extended X-ray absorption fine structure was employed to extract the structural parameters required for understanding the atomic distribution and alloying extent, and to identify the corresponding simulated structures by using FEFF8 code and IFEFFIT software. The electrocatalytic activity of PdCo alloy nanoparticles for the oxygen reduction reaction was evaluated by using rotating disk electrode technique and correlated to the change in structural parameters. We have found that Pd-rich surface was formed on the Co core with increasing heating time over 5 hours. Such core shell structure of PdCo/C showed that a superior oxygen reduction reaction activity than pure Pd/C or alloy phase of PdCo/C electrocatalysts, because the adsorption energy of adsorbates was apparently reduced by lowering the dband center of the Pd skin due to a combination of the compressive strain effect and ligand effect.