나노인덴테이션으로 측정한 Ti(C_0.7N_0.3)-WC-Ni 써멧 구성상의 경도

김성원,김대민,강신후,김형준,김형태,Kim, Seong-Won,Kim, Dae-Min,Kang, Shin-Hoo,Kim, Hyeong-Jun,Kim, Hyung-Tae 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.1

The constituent phases in Ti($C_{0.7}N_{0.3}$)-xWC-20Ni (wt%, x=5, 15, 25) cermets were characterized using nanoindentation in conjunction with observation of microstructure. The microstructure of cermet is composed of hard phase and binder phase, which gave rise to a wide range of hardness distribution when nanoindentation was carried out on the polished surface of cermets. Because of the inhomogeneous nature of cermet microstructure, observation of indented surface was indispensable in order to separate the hardness of each constituent phase. The measured values of hardness using nanoindentation were ${\sim}14\;GPa$ for the binder phase and ${\sim}24$ to 28 GPa for the hard phase, of which nanoindentation hardness was decreased with the addition of WC into Ti($C_{0.7}N_{0.3}$)-Ni system. In addition, the nanoindentation hardness of Ni binder phase was much higher than reported Vickers hardness, which could result from confined deformation of binder phase due to the surrounding hard phase particles.

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.

수업 지도안 분석을 통한 예비 교사의 수업 전문성 변화

김성원(Seong-Won Kim),이소율(Soyul Yi),이영준(Youngjun Lee) 한국컴퓨터정보학회 2020 韓國컴퓨터情報學會論文誌 Vol.25 No.1

본 연구에서는 TPACK 교육을 통해 예비 교사의 수업 전문성 변화를 분석하였다. 이러한 연구를 위하여 예비 교사 20명을 대상으로 김성원과 이영준(2019)에서 개발한 프로그래밍 기반 TPACK 교육 프로그램을 적용하였다. 수업 전문성 분석을 위하여 예비 교사가 작성한 수업 지도안을 분석 틀을 활용하여 분석하였다. 연구 결과, 1차 수업 지도안에서 예비 교사는 테크놀로지 활용이 저조하며, 지식을 전달하거나 실험하는 수업을 설계하였다. 2차 수업 지도안에서는 테크놀로지 활용이 증가하였지만, 교육적 맥락에 따라 테크놀로지가 활용되지 않았다. 3차 수업 지도안에서 모든 예비 교사가 테크놀로지를 교육적 맥락에 따라 활용하는 것을 확인할 수 있었다. 또한, 예비 교사의 수업 전문성은 통계적으로 유의한 향상이 나타났다. This study analyzed the change of teaching expertise of pre-service teachers through TPACK education. In this study, we applied a programming-based TPACK education program developed by Kim and Lee (2019) to 20 prospective teachers. To analyze the pre-service teachers’ teaching expertise analyzed the lesson plan prepared before, during and after applying the educational program. As a result, Few teachers use technology in lesson plan, and the design of the instructor-led or experiment to confirmed content in curriculum or textbook. The use of technology has increased in the second Teaching Plan, but the technology was not used depending on the educational context. In the third lesson plan, all pre-service teachers were able to use technology in an educational context. Moreover, the teaching expertise of the pre-service teacher showed a statistically significant improvement in the lesson plan. This study founded that the programming-based TPACK education program was effective in enhancing the teaching expertise of the pre-service teacher.

이갈이 진단 및 조절용 구내장치의 개발과 신뢰도 조사

김성원,김미은,김기석,Kim, Seung-Won,Kim, Mee-Eun,Kim, Ki-Suk 대한안면통증구강내과학회 2005 Journal of Oral Medicine and Pain Vol.30 No.1

The purposes of this study were to develop and introduce a novel intraoral appliance for bruxism composed of power switch and biofeedback device and further to examine inter- and intra-reliability of the appliance prior to clinical tests. The newly-developed appliance consisted of detection sensors, a central processing unit (CPU), a reactor and a storage unit and a displayer. Compact-sized, waterproof switches were selected as bruxism detection sensor and any sensor activation by clenching or grinding event was processed at the CPU and transmitted, by radio wave, to the reactor and storage unit and triggered auditory or vibratory signal, subsequently producing biofeedback to the patient with bruxism. The data on bruxing event in the storage unit can be displayed on the computer, making it possible analyzing frequency, duration and nature of bruxism. Cast models were obtained from ten volunteers with normal occlusion to evaluate reliability of the appliances. For inter-operator reliability on the intraoral appliances, each operator of the two fabricated the appliance for the same subject and compared the minimal contact forces provoking auditory biofeedback reaction in vertical, lateral and central directions. Intra-operator reliability was also investigated on the appliances made by a single operator at two separate times with an interval of two days. Conclusively, the newly-developed appliance is compact and safe to use in oral circumstance and easy to make. Furthermore, it had to be proven reliability excellent enough to apply in clinical settings. Thus, it is assumed that this appliance with the processor and the storage of data and auditory or vibratory biofeedback function is available and useful to analyze and control bruxism.

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.

이종골 이식을 동반한 지르코니아와 타이타늄 임플란트의 골유착에 관한 연구

김성원,조인호,Kim, Sung-Won,Cho, In-Ho 대한치과보철학회 2014 대한치과보철학회지 Vol.52 No.1

연구 목적: 본 연구에서는 외과적으로 형성한 골 결손부에 이종골 이식과 함께 식립한 지르코니아 임플란트의 골유착에 대한 기계적 안정성과 조직학적 반응을 타이타늄 임플란트와 비교하고자 하였다. 연구 재료 및 방법: 6마리 돼지의 경골에 인위적으로 형성한 골 결손 부위에 대조군인 18개의 상용 타이타늄 나사형 임플란트와 실험군인 18개의 샌드블라스팅한 지르코니아(Y-TZP) 나사형 임플란트를 각각 식립하고 차폐막을 이용하여 이종골을 이식하였으며 1주, 4주, 12주후에 각각 2마리씩 희생시켜 조직 시편을 제작하였다. 식립 직후와 식립 1주, 4주, 12주 후에 각각 페리오테스트를 이용하여 임플란트의 안정성을 측정하였고, 광학현미경으로 조직학적 관찰과 조직계측학적 분석을 하였으며 주사전자현미경으로 임플란트의 표면 특성과 골-임플란트 계면을 관찰하였다. 결과: 페리오테스트를 이용한 임플란트 안정성 분석 결과, 대조군과 실험군 사이에 유의한 차이가 없었고, 조직학적 분석 결과, 각 군 모두 4주에 이식골의 재흡수와 조골세포의 활발한 활동에 의해 신생골이 형성되기 시작하였다. 골-임플란트 접촉률 분석 결과, 대조군과 실험군 사이에 유의한 차이가 있었으며(P<.05), 특히 4주와 12주에서 실험군과 대조군 사이에 2시점에서 유의한 차이를 보였다(P<.05). 골 면적률 분석 결과, 대조군과 실험군 사이에 유의한 차이가 없었다. 주사전자현미경 관찰 결과, 대조군은 균일한 다공성의 거친 표면을 나타냈고 실험군은 무정형 입자들이 불규칙하게 산재된 표면을 보여 주었다. 각 군 모두 4주에 임플란트 표면과 골 조직 사이에 빈 공간이 관찰되었고 12주에는 일부 공간에서 골 조직으로 채워진 양상을 보였다. 결론: 차폐막을 이용한 이종골 이식을 동반하는 경우 본 실험에 사용된 지르코니아 임플란트의 골-임플란트 접촉률은 양극산화 표면처리를 한 타이타늄 임플란트에 크게 미치지 못하므로 지르코니아 임플란트의 실용화를 위해서는 표면 처리 방법 등에 대한 지속적인 연구를 통한 개선이 필요하다고 사료된다. Purpose: The purpose of this study was to compare zirconia implants with titanium implants from the view point of biomechanical stability and histologic response on osseointegration when those were placed with xenograft materials. Materials and methods: Specimens were divided into two groups; the control group was experimented with eighteen titanium implants which had anodized surface and the experimental group was experimented with eighteen sandblasted zirconia (Y-TZP) implants. At the tibias of six pigs, implants were installed into bone defect sites prepared surgically and treated with resorbable membranes and bovine bone. Two pigs were sacrificed after 1, 4 and 12 weeks respectively. Each implant site was sampled and processed for histologic and histomorphometric analysis. The stability of implants was evaluated with a $Periotest^{(R)}$. And the interfaces between bone and the implant were observed with a scanning electron microscope. Results: In stability analysis there was no significant difference between Periotest values of the control group and the experimental group. In histologic analysis with a light microscope after 4 weeks, there was new bone formation with the resorption of bovine bone and the active synthesis of osteoblasts in both groups. In bone-implant contact percentage there was significant difference between both groups (P<.05). In bone area percentage there was no significant difference between both groups. In analysis of both groups with a scanning electron microscope there was a gap between bone and a surface at 4 weeks and it was filled up with bone formed newly at 12 weeks. Conclusion: When accompanied by xenograft using membrane, bone to implant contact percentage of zirconia implants used in this experiment was significantly less than that of the titanium implants by surface treatment of anodic oxidation. So, it is considered that the improvement of zirconia implant is needed through ongoing research on surface treatment methods for its practical use.

고밀도 클러터 환경에서 비선형 표적추적에 강인한 자료결합 게이트 기법

김성원,권택익,조현덕,Kim, Seong-Weon,Kwon, Taek-Ik,Cho, Hyeon-Deok 한국음향학회 2021 韓國音響學會誌 Vol.40 No.2

This paper proposes the H∞ norm based data association gate method to apply robustly the data association gate of passive sonar automatic target tracking which is on non-linear targets in dense cluttered environment. For target tracking, data association method selects the measurements within validated gate, which means validated measuring extent, as candidates for the data association. If the extent of the validated gate in the data association is not proper or the data association executes under dense cluttered environment, it is difficult to maintain the robustness of target tracking due to interference of clutter measurements. To resolve this problem, this paper proposes a novel gating method which applies H∞ norm based bisection algorithm combined with 3-σ gate method under Gaussian distribution assumption and tracking error covariance. The proposed method leads to alleviate the interference of clutters and to track the non-linear maneuvering target robustly. Through analytic method and simulation to utilize simulated data of horizontal and vertical bearing measurements, improvement of data association robustness is confirmed contrary to the conventional method.

국내 대학도서관의 무선인터넷 서비스에 관한 연구

김성원,Kim, Sung-Won 한국과학기술정보연구원 과학기술정보센터 2008 Journal of Information Science Theory and Practice Vol.39 No.2

국내 대학도서관들은 첨단 기술의 발전을 수용하고 이를 기반으로 하는 정보서비스의 기획 및 제공을 통해 도서관 서비스의 발전을 주도하고 있으며, 해당 기관 내에서 정보유통의 중심으로서 도서관의 위상을 공고히 하는 데 기여하고 있다. 본 고에서는 국내 대학도서관들에서 무선인터넷을 통해 제공하고 있는 도서관 정보서비스의 현황을 살펴보고자 한다. 이를 위해 다수 도서관이 참여하고 있는 협의체인 'WDL 모바일 캠퍼스 컨소시엄'을 통해 주도되고 있는 무선인터넷 서비스의 일반현황, 플랫폼의 구성, 서비스의 구성과 주요기능, 이용환경과 현황을 살펴보고 지속적인 발전을 위한 발전방안을 제시하였다. Korean university libraries has lead the advancement of library service by adopting state-of-art technology for the improvement of information service provision, which therefore contributes to the consolidation of the status of the library as a center of information circulation among related institutions. This paper examines the current conditions of wireless internet service provided by the university libraries. First, it takes 'WDL mobile campus consortium', which is an organized movement with many university libraries involved, and explores their major issues such as wireless internet service environment, platform components, service components and functions, user environment and usage. Finally, this paper makes suggestions for the continuous advancement of the university libraries' wireless services.

The Reliability of the Conventional Tomographic Interpretation for the Patients with Temporomandibular Disorders

김성원,김기석,Kim, Sung-Won,Kim, Ki-Suk The Korean Academy of Orofacial Pain and Oral Medi 2001 Journal of Oral Medicine and Pain Vol.26 No.3

본 연구는 측두하악관절장애의 증상이 있는 악관절의 통상적인 방사선 단층촬영술에 대한 해석과 관절강 측정에 대한 조사자내, 조사자간 신뢰도를 조사하였다. 신뢰도 검사는 조사자들 간에 판독의 일관성이 있는지와 일정 시간이 지난 후 반복 측정 시 판독의 정확성이 있는지를 알아보기 위하여 시행하였다. 조사자내 상관계수는 과두 형태에 대해서는 각각 0.812와 0.619, 골변화 형태에 대해서는 모두1.00, 골변화에 대해서는 0.846과 0.991, 전방관절강에 대해서는 0.919와 0.966, 상방관절강에 대해서는 0.864와 0.955, 그리고 후방관절강에 대해서는 0.718과 0.672였다. 통상적인 방사선 단층촬영술이 신뢰도가 있음을 보여주는 이 연구의 결과로 보아, 측두하악 관절을 평가하는데 있어서 통상적인 방사선 단층촬영술은 높은 진단학적 정확성과 조사자간 일치성을 가진다고 할 수 있다.

출발 1999 전망과 회고-과학

김성원,Kim, Seong-Won 대한출판문화협회 1999 출판저널 Vol.249 No.-

지난해의 연장 속에서 환경문제와 함께 인간 복제문제, 상대성이론과 시간과 관련된 내용들, 노벨상과 관련된 대중서가 계속 소개될 것이다. 중요한 것은 외국서적을 단순히 번역할 뿐만 아니라 국내 저자가 저술한 책의 출간이 필요하다는 점이다.