실리콘 나노선/다중벽 탄소나노튜브 Core-Shell나노복합체의 합성

김성원,이현주,김준희,손창식,김동환,Kim, Sung-Won,Lee, Hyun-Ju,Kim, Jun-Hee,Son, Chang-Sik,Kim, Dong-Hwan 한국재료학회 2010 한국재료학회지 Vol.20 No.1

Si nanowire/multiwalled carbon nanotube nanocomposite arrays were synthesized. Vertically aligned Si nanowire arrays were fabricated by Ag nanodendrite-assisted wet chemical etching of n-type wafers using $HF/AgNO_3$ solution. The composite structure was synthesized by formation of a sheath of carbon multilayers on a Si nanowire template surface through a thermal CVD process under various conditions. The results of Raman spectroscopy, scanning electron microscopy, and high resolution transmission electron microcopy demonstrate that the obtained nanocomposite has a Si nanowire core/carbon nanotube shell structure. The remarkable feature of the proposed method is that the vertically aligned Si nanowire was encapsulated with a multiwalled carbon nanotube without metal catalysts, which is important for nanodevice fabrication. It can be expected that the introduction of Si nanowires into multiwalled carbon nanotubes may significantly alter their electronic and mechanical properties, and may even result in some unexpected material properties. The proposed method possesses great potential for fabricating other semiconductor/CNT nanocomposites.

나노인덴테이션을 이용한 Ti(C_0.7N_0.3)-NbC-Ni 써멧 구성상의 경도평가

김성원,김대민,강신후,류성수,김형태,Kim, Seong-Won,Kim, Dae-Min,Kang, Shin-Hoo,Ryu, Sung-Soo,Kim, Hyung-Tae 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.6

The indentation technique has been one of the most commonly used techniques for the measurement of the mechanical properties of materials due to its experimental ease and speed. Recently, the scope of indentation has been enlarged down to the nanometer range through the development of instrumentations capable of continuously measuring load and displacement. In addition to testing hardness, the elastic modulus of submicron area could be measured from an indentation load-displacement (P-h) curve. In this study, the hardness values of the constituent phases in Ti($C_{0.7}N_{0.3}$)-NbC-Ni cermets were evaluated by nanoindentation. SEM observation of the indented surface was indispensable in order to separate the hardness of each constituent phase since the Ti($C_{0.7}N_{0.3}$)-based cermets have relatively inhomogeneous microstructure. The measured values of hardness using nanoindentation were ${\sim}20$ GPa for hard phase and ${\sim}10$ GPa for binder phase. The effect of NbC addition on hardness was not obvious in this work.

국내 현생 심성암류의 방사성 물질의 농도 및 의미

김성원,Kim, Sung Won 대한자원환경지질학회 2020 자원환경지질 Vol.53 No.5

최근 생활용품 및 건축자재 등에서 검출된 자연 방사성 물질로 인해 사회적으로 다양한 문제가 발생하고 있으며, 이는 조속히 해결해야 될 사회현안으로 대두되고 있다. 우리나라에서도 토양이나 지하수 내 중금속 및 우라늄, 라돈 등의 자연방사성 물질에 대해서 환경부에 의해 지난 20년 이상 장기간 조사된 바 있고, 토양과 지하수 내 자연방사성 물질의 기원이 암석-성인-변형적 특성 등의 지질학적 요인들과 밀접한 상관관계를 보여주는 것으로 추정되고 있지만, 기반암, 기반암 상부토양 및 지하수가 발달한 단층계 내 자연방사성 물질의 국가배경농도가 수립되어 있지 않아 정확한 지질학적 상관관계 규명이 미흡한 실정이다. 본 연구에서는 국내 현생 심성암류의 성인과 천연 방사성(라돈, 우라늄, 토륨 등)물질 농도와의 상관관계에 대한 예비 연구를 수행하였다. 현생 심성암류 중 알칼리 화강암류(섬장암, 몬조니암, 몬조섬록암 및 알칼리화강암)는 높은 마그마 온도와 고알칼리성의 경향 때문에 U, Th, Zr, REE 및 Nb 등이 부화되는 특징을 보여주어 높은 U과 Th 농도를 가진다. 지각물질의 혼합에 의해 고분화된 화강암류(우백질 화강암, 복운모화강암, 고알루미형질 S-type 화강암 및 페그마타이트)는 고분화되지 않은 일반 화강암류(섬록암, 화강섬록암 및 화강암)보다 U, Th 및 K+Na이 더욱 부화되는 경향을 보여준다. 고알칼리성 화강암류들은 주로 판내부의 열개환경, 대륙충돌 조산작용과 해양판의 대륙판 아래 섭입 이후에 일어나는 확장환경에서 생성된다. 반면에 우리나라에서 주로 산출되는 아알칼리성 캘크알칼리 화강암류는 해양판의 대륙판 밑으로의 섭입에 의한 호환경에서 주로 생성된다. 결과적으로 국내 현생 심성암류의 U, Th 및 K 함량변화는 지구조 환경에 의한 암석성인과 밀접한 연관성을 가지는 것으로 추정되며, 현생화강암류 대한 감마분석 자연방사성 핵종(²²⁶Ra, ²³²Th 및 ⁴⁰K) 예비 결과들은 고알칼리성과 고분화된 화강암류에서 높은 값을 보여준다. In recent years, various social issues related to the natural radioactive elements detected in household goods and building materials are addressed, and should be solved promptly. In Korea, for more than 20 years, the Ministry of Environment has investigated the natural radioactive materials such as heavy metals, uranium, and radon in soil or groundwater. The origins of natural radioactive materials in them may have a close correlation with the geological factors including classification of rocks, petrogenetic origins, and deformation characteristics, but the exact geological correlations are not clarified because of the absence of the government policy preserved in the basement rocks, soils as well as groundwater in fault-related reservoirs. This study aims to perform a research on the correlation between the petrogeneses of the Phanerozoic plutonic rocks and natural radioactive concentrations in rocks (radon, uranium, thorium, potassium etc.) in Korea. Among the Phanerozoic plutonic rocks, alkaline plutonic rocks (syenite, monzonite and monzodiorite and alkali granite) show high U and Th concentrations by high solubilities of U, Th, Zr, REE, and Nb until the most extreme stages of magmatic fractionation (viz. crystal fractionation) due to high magma temperature and high alkalinity tendency. The highly fractionated high-K calalkaline and peraluminous granitic rocks (leucogranite, two-mica granite and leucocratic pegmatite are also U and Th concentrations compared with other less or medium fractionated granitic rocks (diorite, granodiorite and granite). The alkaline plutonic rocks are associated with intracontinental rifting and extensional environment after crustal thickening by collisional and subductional processes. In contrast, the dominant calc-alkaline granitic rocks in Korea are related to the arc environment of the subduction zone. In summary, the trends of the U, Th and K concentration from the Phanerozoic plutonic rocks in Korea are closely linked to the petrogenesis of the rocks in tectonic environment. The preliminary data for gamma-spectrometric mesurments of natural radionuclide contents (²²⁶Ra, ²³²Th and ⁴⁰K) in the Phanerozoic plutonic rocks show high values in the alkaline and highly fractionated granitic rocks.

접착재 종류와 정착구 유무에 따른 탄소막대 매립보강 RC보의 휨 거동에 관한 실험적 연구

김성원,이형근,여환준,박성무,Kim, Sung-Won,Lee, Hyung-Geun,Yeo, Hwan-Jun,Park, Sung-Moo 한국공간구조학회 2014 한국공간구조학회지 Vol.14 No.4

For the last decade many bridges and buildings have experienced flexural strengthening with the fiber reinforced polymer(FRP) bonding system, demands for increasing heavy traffic loads and the changing of the code application. Of the many strengthening systems, NSM(near surface mounted) system with FRP has become attractive and popular way of strengthening for the existed RC structures and many studies and applications of this technique have significantly increased all over the world. Meanwhile, polymer mortar that contains much of the same ingredients as cement but includes the addition of certain polymer resins for enhancing desired physical properties, has been used as an alternative adhesive. This paper focuses on flexural behaviour of CFRP-bar NSM system with variables such as kinds of adhesive, anchorage, sectional aspect ratio. Based on the test results and test-to-predicted ratio, this paper provides researchers and practical engineers a fundamental knowledge and intuition.

무선 멀티캐스트 전송률의 적응적 제어기법

김성원,Kim, Sung-Won 한국정보통신학회 2009 한국정보통신학회논문지 Vol.13 No.8

Multicast can transmit data packet to multiple terminals by using only one transmission and enhances the system performance. However, the multicast transmission rate is fixed and the system performance is not optimized. In this paper, we propose an adaptive multicast rate control method. In the proposed method, orthogonal subcarrier is assigned to each terminal. Each terminal informs the channel status using the allocated subcarrier. Transmitter selects the optimal rate using the feedback information. With the proposed adaptive rate control method, the system performance is enhanced compared with the legacy multicast method. 한 번의 전송으로 다수의 단말기에 데이터를 전송할 수 있는 멀티캐스트 전송기법은 무선 네트워크의 효율성을 증대시킨다. 하지만 멀티캐스트의 전송률은 고정되어 있어서 효율성이 최적화 되어 있지 않다. 본 논문에서는 무선네트워크에서 다중 전송에 사용되는 멀티캐스트의 전송률을 적응적으로 제어하는 방법을 제안한다. 제안하는 방법에서 각 단말기는 고유한 서브캐리어를 할당받고, 이 서브캐리어를 사용하여 채널 상태를 송신기에게 알려준다. 송신기는 이러한 피드백 정보를 사용하여 최적의 전송률을 사용할 수 있게 된다. 이러한 전송률 제어기법을 사용하게 되면, 시스템 성능 향상을 이룰 수 있게 된다.

Fracture Properties of Carbon Coated LPS-SiC_f/SiC Composites

김성원,이문희,황승국,이상필,Kim, Sung-Won,Lee, Moon-Hee,Hwang, Seung-Kuk,Lee, Sang-Pill The Korean Society of Industry Convergence 2017 한국산업융합학회 논문집 Vol.20 No.2

Mechanical properties of carbon coated $SiC_f/SiC$ composites have been investigated, in conjunction with a detailed analysis of microstructure. Especially, the fracture behavior of $SiC_f/SiC$ composites by the induction of carbon coating layers has been examined. The matrix region of $SiC_f/SiC$ composites with ultra-fine SiC powders were consolidated by a liquid phase sintering (LPS) process, using a sintering additive of $Al_2O_3-Y_2O_3$ powder compound. In this composite, plain and satin- woven Tyranno SA fabrics were also utilized as a reinforcing material. A carbon interfacial layer was coated around satin-woven SiC fabrics. The characterization of LPS-$SiC_f/SiC$ composites was investigated by means of SEM and three point bending test.

용융금속을 2차측으로 하는 편측식 선형유도전동기의 특성해석

金昌業 湖西大學校工業技術硏究所 1999 工業技術硏究所論文集 Vol.18 No.-

This paper presents the characteristics analysis of a single-sided linear induction motor with secondary molten metals. The characteristics of a linear induction motor are analysed by the equivalent circuit method considering the end effects. For the verification of the analysis method, the locked test and load test with molten tin were made. The test results of locked test were compared with the simulations, and the velocity of the load test with molten tin showed 0.24[m/s] with air gap 30[mm] which is sufficient for transferring molten tin.

한국(韓國)의 전자정부(電子政府)와 거버넌스 향상 방안

김성원,김종성,Kim, Sung-Won,Kim, Jong-Seong 한국과학기술정보연구원 과학기술정보센터 2012 Journal of Information Science Theory and Practice Vol.43 No.3

한국의 전자정부 구축 현황을 살펴보고 전자정부를 통하여 거버넌스의 향상에 기여할 수 있는 방안에 대해 고찰해 보았다. 한국의 전자정부는 구현 수준에 있어 국제적 평가에서 상위권에 위치하는 것을 확인할 수 있었으나 전자정부 발전의 최종단계인 통합처리의 관점에서는 지속적인 개선 노력이 필요한 상황으로 평가되었다. 한국의 전자정부가 거버넌스의 향상에 어느 정도 기여하고 있는가를 평가하기 위해 공급자와 이용자의 관점에서 전자정부의 활용도를 평가하였으며 거버넌스와 관련된 기능의 제공 및 활용이라는 정성적인 관점에서 활용도를 평가해 보았다. 한국의 전자정부 활용도는 정량적인 관점에서 상당한 수준에 도달해 있으나 거버넌스의 향상에 기여할 수 있는 이용목적이라는 정성적인 관점에서는 여전히 개선의 여지가 있는 것으로 평가되었다. 위와 같은 평가에 기반하여 전자정부를 통한 거버넌스 향상을 위해 필요한 고려사항들을 제시하였다. This study examines the status of Korean E-government implementation and explores the ways to contribute to governance improvement by means of the e-government. As far as the level of implementation of e-government, Korea is confirmed to have achieved upper level by global standards, but it is found that continuous efforts of improvement is still required in the area of integrative management, which is considered as a final phase of e-government development. In order to evaluate how much e-government of Korea has contributed to the improvement of governance, I tried to measure the usability of e-government from the perspective of providers and that of consumers, and also, a qualitative evaluation on the provision and usage of functions related to the governance was also adopted. It is concluded that, while Korean e-government has reached a remarkable stage in the quantitative perspectives, there are still a room for improvement from the qualitative perspective, such as its role as a means of governance improvement. Also, based on the above evaluations and consequent findings, I suggest guidelines for the improvement of governance through the development of e-government.

비선형 증발량 및 증발산량 시계열의 모형화를 위한 신경망-유전자 알고리즘 모형 2. 불확실성 분석에 의한 최적모형의 구축

김성원,김형수,Kim, Sung-Won,Kim, Hung-Soo 한국수자원학회 2007 한국수자원학회논문집 Vol.40 No.1

본 논문에서는 본 연구논제(2007)에서 개발된 COMBINE-GRNNM-GA(Type-1)으로부터 최적형태의 구조를 가진 모형을 구성하고, 입력층노드의 기상인자를 제거하기 위하여 불확실성 분석을 실시하였다. 훈련과정중에 가장 최소의 평활인자를 가진 입력층변수는 COMBINE-GRNNM-GA(Type-1)에서 제거되었으며, 변형된 COMBINE-GRNNM-GA(Type-1)은 기상학적 변수의 새로운 최소 평활인자를 구하기 위하여 재훈련된다. 최소 평활인자를 가지는 입력층 노드는 모형결과치에 대하여 가장 유용하지 않는 기상인자인 것을 암시하고 있다. 게다가, 민감하거나 민감하지 않은 기상인자들이 불확실성 분석을 통하여 선택되어진다. 최적 COMBINE-GRNNM-GA(Type-1)은 최소 비용과 노력으로 결측 혹은 미계측 증발접시 증발량과 계측되고 있지 않은 알팔파 기준증발산량을 산정하기 위하여 개발되었다 마지막으로 치적 COMBINE-GRNNM-GA(TyPe-1)을 이용하여 우리나라에서 전반적인 가뭄해석 및 관개배수 시스템 구축을 위한 참고자료를 제공할 수 있는 증발접시 증발량 지도 및 알팔파 기준증발산량 지도도 구축되어질 수 있다. Uncertainty analysis is used to eliminate the climatic variables of input nodes and construct the model of an optimal type from COMBINE-GRNNM-GA(Type-1), which have been developed in this issue(2007). The input variable which has the lowest smoothing factor during the training performance, is eliminated from the original COMBINE-GRNNM-GA (Type-1). And, the modified COMBINE-GRNNM-GA(Type-1) is retrained to find the new and lowest smoothing factor of the each climatic variable. The input variable which has the lowest smoothing factor, implies the least useful climatic variable for the model output. Furthermore, The sensitive and insensitive climatic variables are chosen from the uncertainty analysis of the input nodes. The optimal COMBINE-GRNNM-GA(Type-1) is developed to estimate and calculate the PE which is missed or ungaged and the $ET_r$ which is not measured with the least cost and endeavor Finally, the PE and $ET_r$. maps can be constructed to give the reference data for drought and irrigation and drainage networks system analysis using the optimal COMBINE-GRNNM-GA(Type-1) in South Korea.

치밀화된 Ti(C,N)과 TiC-TiN-Ni 써멧에서의 Ti(C,N) 고용상의 특성평가

김성원,채정민,강신후,류성수,김형태,Kim, Seong-Won,Chae, Jung-Min,Kang, Shin-Hoo,Ryu, Sung-Soo,Kim, Hyung-Tae 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.6

Ti(C,N) solid solutions in hot-pressed Ti($C_{x}N_{1-x}$) (x=0.0, 0.3, 0.5, 0.7, 1.0) and 40TiC-40TiN-20Ni (in wt.%) cermet were characterized in this study. For hot-pressed Ti(C,N)s, the lattice parameters and hardness values of Ti(C,N) were determined by using XRD (X-Ray Diffraction) and nanoindentation. The properties of hot-pressed Ti(C,N) samples changed linearly with their carbon or nitrogen contents. For the TiC-TiN-Ni cermet, the hardness of the hard phase and binder phase were determined by nanoindentation in conjunction with microstructural observation. The measured hardness values were ${\sim}8.7$ GPa for the binder phase and ${\sim}28.7$ GPa for the hard phase, which was close to the hardness of hot-pressed Ti($C_{0.7}N_{0.3}$).