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.

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.

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.

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).

토양자원 관리를 위한 표토침식모형의 개선방향

김성원,Kim, Seong-Won 한국수자원학회 2019 물과 미래(한국수자원학회지) Vol.52 No.8

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.

국가측정표준제도-각국의 국가측정표준 관계법 비교고찰

김성원,Kim, Seong-Won 한국과학기술단체총연합회 1983 과학과 기술 Vol.16 No.12

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.

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.