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.

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.

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.

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.

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.

OFDM 기반 무선 네트워크의 전송률 제어 기법

김성원,Kim, Sung-Won 한국정보통신학회 2008 한국정보통신학회논문지 Vol.12 No.9

OFDM 기반 무선 네트워크 시스템에서 서브캐리어(subcarrier) 단위로 전송률을 제어하는 기법을 제안한다. 제안된 프로토콜은 IEEE 802.11 표준에 정의된 CTS 프레임에 하나의 OFDM 심벌을 추가하여 구현된다. 수신기는 RTS 프레임을 수신한 후 해당 서브캐리어에 적절한 전송률을 결정하고, 이 결과를 CTS에 추가된 OFDM 심벌을 통하여 전달한다. 송신기와 수신기 사이의 전송률을 일치시키기 위한 에러 복구 방법도 제안한다. 제안된 기법을 통하여 무선 네트워크 시스템의 성능 향상이 이루어짐을 보인다. A protocol is proposed to control the rate of each subcarrier in OFDM-based wireless network systems. The proposed protocol adds an OFDM symbol in CTS frame defined in IEEE 802.11 standard. A receiver determines the rate of its subcarrier after it receives the RTS frame. The determined rate is added to OFDM symbol in CTS frame. In order to synchronize the rate information between the sender and the receiver, error recovery process is proposed. The performance improvement of the proposed method is shown by numerical results.

Reconstitution of Iron Cores in Horse Spleen and Yeast-derived Recombinant Human H- and L-chain Ferritins

김성원,Min-Young Jo,Yasuhiro Yokota,Yun-Jo Chung,Chung-Ung Park,Kyung-Suk Kim* 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.2

밀폐형 원심회전차의 내부유동장에 관한 실험적 연구-무충돌 유입 조건에서-

김성원,조강래,Kim, Seong-Won,Jo, Gang-Rae 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.10

Flow patterns were measured in a shrouded centrifugal impeller. The flow rate in measurements was fixed at the value corresponding to a nearly zero incidence at the blade inlet. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes from the inlet to the outlet of impeller rotating at 700 rpm, and the static pressure distribution along flow passage and the slip factor at impeller outlet were calculated from the measured values. From these measured data, the primary and secondary flows, the wake production and the static pressure rise in the impeller passage were investigated. Furthermore, the secondary flow patterns and the wake's location in this impeller passage were compared with those of the unshrouded impeller.

멀티캐스트 학내 방송서비스 구현

김성원,Kim, Sung-Won 한국과학기술정보연구원 과학기술정보센터 2009 Journal of Information Science Theory and Practice Vol.40 No.2

Most of the colleges run their own broadcasting stations. They provide diverse types of content, and nowadays many colleges even provide video content. This paper deals with the concept of multicast service as a solution to provide efficient broadcasting service on the college campus. For this purpose, it examines concept and characteristics of the multicast service. It also reviews the actually case of such service provided by S college in Seoul, focusing on its platform, major functions, and scenario. I expect what's discussed in this paper contribute to effective implementing and operating of a college broadcasting service. Also, multicast service introduced in this paper is applicable to the various organizational environment such as private companies and institutions as well as colleges. 상당수 대학은 자체 방송국을 운용하고 있다. 방송의 내용도 다양해져 학내 영상서비스를 제공하는 대학도 다수에 이른다. 본 고에서는 이러한 환경을 반영하여 효율적인 학내 방송서비스를 제공하기 위한 솔루션으로 멀티캐스트 서비스의 구현문제를 다루었다. 이를 위해 멀티캐스트 서비스의 개념과 특징을 살펴보았다. 또한 서비스의 시나리오, 플랫폼, 주요 기능 등 구현된 서비스를 서울 소재 S대학의 사례를 중심으로 살펴보았다. 본 고에서 소개된 내용을 기반으로 하여 학내 효율적인 방송서비스를 구축, 운영하는 실무에 도움을 줄 수 있기를 기대한다. 본 고에서 소개된 멀티캐스트 서비스는 대학뿐아니라 일반 기업 및 협회 등 다양한 조직에서 활용될 수 있을 것으로 기대한다.

이용자관점에서의 도서관 2.0 서비스 활용현황과 활성화 방안 - 폭소노미 서비스를 중심으로 -

김성원,김정우,Kim, Sungwon,Kim, Jeongwoo 한국비블리아학회 2013 한국비블리아학회지 Vol.24 No.2

The development of IT (information technology) has brought about many types of new services, and the traditional sectors such as libraries and information management fields have actively applied new technology to improve the quality of their services. Many of these newly developed services are described under the term 'Web 2.0', in the sense they are next-generation forms of services, and this coinage is duplicated in the term 'Library 2.0', specifically referring to the library services equipped with Web 2.0 technology. Active acceptance of advanced IT to library services is very important to enhance the value and role of library in this rapidly changing information environment. So far, libraries in Korea and abroad have already been putting a lot of efforts and resources to develop and provide technically advanced services. Despite these efforts, it is found that some of these new services have failed to attract users' attention and interest, resulting in the low rates of usage. This study, therefore, reviews current state of the "Folksonomy" based services provided in Korean college libraries as a type of Library 2.0 services, and assess their usage rates. The result of this evaluation is then used to develop a guideline to improve and mobilize the use of such services. 정보통신기술의 발전과 진화는 다양한 분야에서 새로운 유형의 서비스들을 등장시키고 있으며, 도서관을 비롯한 정보관리분야에서도 새로운 기법들을 적용한 서비스의 개발과 제공이 활발히 추진되고 있다. 새로운 기법을 적용하여 개발된 서비스들을 진화된 웹 서비스라는 관점에서 '웹 2.0'이라는 용어로 통칭하고 있으며, 이러한 웹 2.0의 기법이 적용된 도서관서비스를 '도서관 2.0'으로 특정하여 부르기도 한다. 기술적인 진보를 도서관서비스에 적용하고자 하는 노력은 급변하는 정보환경 속에서 도서관의 가치와 역할을 증대시킬 수 있는 의미 있는 일이다. 국내외 도서관들도 새로운 기법을 적용한 서비스를 개발하고 제공하기 위해 많은 자원과 노력을 투입하고 있다. 이러한 노력에도 불구하고 새롭게 제공되는 서비스들 가운데 일부는 이용자의 관심과 호응을 얻지 못하고 저조한 사용률을 보이는 것으로 파악된다. 본 연구는 국내 대학도서관을 중심으로 도서관 2.0 서비스의 하나인 폭소노미 서비스의 제공현황과 그 활용도를 평가하고, 이러한 평가결과를 기반으로 이용을 활성화시킬 수 있는 방안을 도출하여 제시하였다.