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.

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.

한국인명의 로마자표기 형식에 대한 연구

김성원,김정우,Kim, Sung-Won,Kim, Jeong-Woo 한국과학기술정보연구원 과학기술정보센터 2012 Journal of Information Science Theory and Practice Vol.43 No.2

한국인들의 국제활동 증대에 따라 외국인들과의 접촉이 증가하였으며 활동의 주체인 한국인 개인을 외국인이 식별해야 하는 필요가 증대되고 있다. 개인을 식별해주는 것은 개인의 이름(personal name)이며, 한글(Hangeul, Korean alphabet)을 모르는 외국인이 한국인을 식별할 수 있도록 하려면 한국인명을 로마자로 표기하는 음성번역(phonetic translation)이 필요하다. 한국인명의 로마자표기 실태를 보면 다양한 형식이 혼용되고 있어 혼돈이 벌어지고 있다. 한국인명을 로마자로 표기하는 과정에서 발생하는 혼돈은 크게 한국인명을 표기하기 위한 로마자 자모의 선택과 표기형식의 상이함에서 비롯된다. 본 연구는 한국인명의 로마자표기를 위한 형식을 검토하여 최적안을 제안하는 것을 목적으로 하였다. 이를 위해 한국과 서구간의 인명 구조와 사용관행의 차이를 살펴보고, 한국인명의 로마자표기의 의미와 관련쟁점을 정리하였으며, 현재 사용되고 있는 다양한 표기형식을 유형화하였다. 이를 기반으로 한국인명의 로마자표기에 사용되고 있는 다양한 형식을 검토하고 최적안이라 판단되는 표기형식을 제안하였다. Due to the increase of international business and activities, Koreans nowadays have higher needs to present their personal identity to the foreigners. In this process, the first requirement is to exchange personal names with foreigners. Therefore, the phonetic translation of Korean names into Roman alphabetic notation is frequently required, in order to deliver Korean personal names to the people who do not understand Korean alphabet. However, some confusions have been witnessed in the way of transforming Korean names into Roman (English) alphabet notation, due to the fact that there are many different ways to put Korean pronunciation into Roman (English) alphabet. This study examines different formats of Romanization of Korean personal names to find and suggest an optimal one. It first examines structures of and differences between Korean and Western personal names and usage patterns, reviews the issues surrounding Romanization of Korean personal names, and patternizes diverse Romanization formats currently used. Based on these examinations and consequent findings, I would like to suggest a format for the Romanization of Korean personal names which is considered to be the best.

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.

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.

ZrB₂-SiC 복합세라믹스의 미세구조와 열전도도에 미치는 SiC 크기와 첨가량의 영향

김성원,권창섭,오윤석,이성민,김형태,Kim, Seong-Won,Kwon, Chang-Sup,Oh, Yoon-Suk,Lee, Sung-Min,Kim, Hyung-Tae 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.5

This paper reports the microstructures and thermal conductivities of $ZrB_2$-SiC composite ceramics with size and amount of SiC. We fabricated sintered bodies of $ZrB_2$-x vol.% SiC (x=10, 20, 30) with submicron and nanosized SiC densified by spark plasma sintering. Microstructure retained the initial powder size of especially SiC, except the agglomeration of nanosized SiC. For sintered bodies, thermal conductivities were examined. The observed thermal conductivity values are 40~60 W/mK, which is slightly lower than the reported values. The relation between microstructural parameter and thermal conductivity was also discussed.

통증학설에 대한 문헌적 고찰

김성원,Kim, Sung-Won 대한물리치료과학회 2002 대한물리치료과학회지 Vol.9 No.1

Pain, which is the most significant issue for the physical therapist, is the cause of various diseases until it disappears, and results in a lot of obstructions to treatment. Pain is very complicated. It is a subjective symptom that informs of a pathologic condition in the body, and one of the unpleasant experiences that people have. It is accompanied with anxiety and fear. Many researchers including Krause(1987) have identified the pain mechanism based on pain perception for many centuries and they have suggested many theories as they believed that pain management was possible. Reviewing the contents of psychoanalysis, uncontrollable pain that can't be explained is described as a defense mechanism to an unconscious psychological conflict. That is, mental pain is transferred to the body and the pain becomes unbearable. What is important is, like Keefe(1992) said, that the pain experience itself is primary stress and one should cope with it, whatever the cause of the pain. This paper investigates the background of the psychological theory of pain. Based on the efforts of previous studies, the next research generation will understand the treatment process for pain more dearly and will contribute to the prevention and protection from pain that humans undergo.

Kaltenborn-Evjenth 정형도수치료가 측두하악관절 운동제한 개선에 미치는 효과

김성원,홍완성,Kim, Sung-Won,Hong, Wan-Sung 대한물리치료과학회 2003 대한물리치료과학회지 Vol.10 No.2

The purpose of this study is to prove the efficacy of the Kaltenborn-Evjenth Orthopedic Manipulative Therapy and the Conventional Physical Therapy that influence changes in pain and range of motion when those therapies are applied to patients with temporomandibular pint movement restriction. The subjects of the study were 30 randomly selected patients who had been diagnosed with temporomandibular pint movement restriction and had endured pain for more than two weeks. These patients had visited one of three hospitals in Pyongchon 00 Hospital. The subjects were divided into two groups with 15 patients each. The Kaltenborn-Evjenth Orthopedic Manipulative Therapy was applied to one group and the Conventional Physical Therapy was applied to the other group, once a day for three days. Then, the pain perception degree was measured by using the Visual Analogue Scale(VAS) and a digital device(Absolute Digimatic) measured the range of motion for each group. The average and standard errors were calculated for each measured items and a paired t-test was used for identifying significance in the differences in the pain perception degree and the range of motion between the two groups according to therapy. The significant level was set as ${\alpha}=0.05$. The changes in the pain perception degree were statistically significant in both groups; however, the group that received Kaltenborn-Evjenth Orthopedic Manipulative Therapy(KE-Group) showed more significant changes in a decrease in the pain perception degree than did the group that received the Conventional Physical Therapy(CPT-Group). Both groups showed significant results regarding changes in the range of motion: however, the KE-Group showed more of a significant difference in the average of the range of motion than did the CPT-Group(p<0.001). Comparing the changes in the range of motion between the two groups, the KE-Group showed a significant result which means that the KE-Group had a higher therapy effect than did the CPT-Group(p<0.05). Based on the results of this study, we found that the Kaltenborn-Evjenth Orthopedic Manipulative Therapy decreased pain and increased the range of motion. With such findings, we expect that the Kartenborn-Evjenth Orthopedic Manipulative Therapy can be used as an effective treatment method for patients with tempomrnandibular pint movement restriction and that the treatment period can be reduced with this therapy as well.

PRAM을 위한 (GeTe)_x(Sb₂Te₃) (x=0.5, 1, 2, 8) 박막의 물성 및 상변환 특성 연구

김성원,송기호,이현용,Kim, Sung-Won,Song, Ki-Ho,Lee, Hyun-Yong 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.7

In this work, we report several experimental data capable of evaluating the phase transformation characteristics of GeSbTe pseudobinary thin films comprehensively utilized as phase change materials. The phase transformation of the GeSbTe thin films was confirmed by XRD measurement from amorphous to hexagonal structure via fee structure except for $Ge_8Sb_2Te_{11}$. In addition, X-ray photoelectron spectra analysis revealed to weaken Ge-Te bond for $Ge_2Sb_2Te_5$ and to strengthen the bonds of all elements for $Ge_8Sb_2Te_{11}$ during the amorphous to crystalline transition. The values of optical energy gap $(E_{OP})$ were around 0.71 and 0.50 eV and the slopes of absorption in extended region (B) were ${\sim}5.1{\times}10^5$ and ${\sim}10{\times}10^5cm^{-1}{\cdot}V^{-1}$ for the amorphous and fcc-crystalline structures, respectively. Finally, the kinetics of amorphous-to-crystalline phase change on the GeSbTe films was characterized using a nano-pulse scanner with 658-nm laser diode (power; $1{\sim}17$ mW, pulse duration; $10{\sim}460$ ns).

Ag-첨가 Ge₂Sb₂Te₅ 박막의 물성 및 고속 결정화

김성원,송기호,이현용,Kim, Sung-Won,Song, Ki-Ho,Lee, Hyun-Yong 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.7

We report several experimental data capable of evaluating the amorphous-to-crystalline (a-c) phase transformation in $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ (x = 0, 0.05, 0.1) thin films prepared by a thermal evaporation. The isothermal a-c structural phase changes were evaluated by XRD, and the optical transmittance was measured in the wavelength range of $800{\sim}3000$ nm using a UV-vis-IR spectrophotometer. A speed of the a-c transition was evaluated by detecting the reflection response signals using a nano-pulse scanner with 658 nm laser diode (power P = $1{\sim}17$ mW, pulse duration t = $10{\sim}460$ ns). The surface morphology and roughness of the films were imaged by AFM. It was found that the crystallization speed was so enhanced with an increase of Ag content. While the sheet resistance of c-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was similar to that of c-phase $Ge_2Sb_2Te_5$ (i.e., $R_c{\sim}10{\Omega}/{\square}$), the sheet resistance of a-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was found to be lager than that of a-phase $Ge_2Sb_2Te_5$, $R_a{\sim}5{\times}10^6{\Omega}{/\square}$. For example, the ratios of $R_a/R_c$ for $Ge_2Sb_2Te_5$ and $(Ag)_{0.1}(Ge_2Sb_2Te_5)_{0.9}$ were approximately $5{\times}10^5$ and $5{\times}10^6$, respectively.