난치성 족저 근막염의 체외충격파를 이용한 치료

최우진,이진우,곽윤해,Choi, Woo-Jin,Lee, Jin-Woo,Kwak, Yoon-Hae 대한족부족관절학회 2007 대한족부족관절학회지 Vol.11 No.1

Purpose: The objective of this study was to report the outcomes of patients treated with extracorporeal shock wave therapy (ESWT) for refractory plantar fasciitis of the foot. Materials and Methods: From November 2005 to October 2006, a total of sixty-two patients with refractory plantar fasciitis were treated with extracorporeal shock wave therapy. The main outcome measurements were visual analogue scale (VAS) and Roles and Maudsley score evaluated before treatment and at one and six months after treatment. Results: Roles and Maudsley score was excellent (0%), good (6.4%), fair (35.4%) and poor (58.2%) before treatment which improved to excellent (56.5%), good (38.7%), fair (4.8%) and poor (0%) at final follow-up. VAS scores also significantly improved after ESWT (p<0.05). There was no statistically significant correlation between clinical results and body mass index (BMI) (p=0.102). Conclusion: Extracorporeal shock wave therapy appears to be an effective and safe treatment modality for refractory plantar fasciitis and may help the patient to avoid surgery for refractory heel pain.

족부 및 족근관절에 발생한 종양 (185예)

최우진,신규호,이진우,한창욱,Choi, Woo-Jin,Shin, Kyoo-Ho,Lee, Jin-Woo,Han, Chang-Wook 대한족부족관절학회 2007 대한족부족관절학회지 Vol.11 No.1

Purpose: Tumors arising in the foot and ankle are uncommon and the malignant tumors are known to be rare compared with those of the other sites. We analyzed the clinical data of patients who have been diagnosed as having a tumor of the foot and ankle. Materials and Methods: From 1989 to 2006, we analyzed 185 patients who have been treated surgically and were pathologically confirmed of having tumors of the foot and ankle. Their clinical characteristics were reviewed retrospectively. Results: One hundred and fifty-seven cases were benign (84.9%) and 28 cases (15.1%) were malignant. 108 cases (58.4%) were benign soft tissue tumors and 49 cases (26.5%) were benign bone tumors. Malignant tumors included 17 cases (9.2%) of soft tissue tumors, 8 cases (4.3%) of primary bone tumors and 3 cases (1.6%) of metastatic bone tumors. The most common benign soft tissue tumor was ganglion (23 cases). Enchondroma (9 cases) was the most common among the benign bone tumors. Malignant peripheral nerve sheath tumor was the most common malignant tumor (4 cases). The predilection site for benign tumors was at the forefoot around toes while for the malignant tumor was around the ankle. 4.6% of benign soft tissue tumors and 8.2% of benign bone tumors had locally recurred and 14 cases (50%) of malignant tumor were confirmed as having distant metastasis. Conclusion: The ratio of malignant tumor and its metastasis rate was high. Therefore, the histopathologic confirmation is essential when treating tumors of the foot and ankle.

관절경적 미세골절술이 실패한 거골의 골연골 병변에 대한 치료로서의 재차 미세골절술

최우진,박광환,이모세,정광호,이진우,Choi, Woo Jin,Park, Kwang Hwan,Lee, Moses,Chung, Kwangho,Lee, Jin Woo 대한족부족관절학회 2015 대한족부족관절학회지 Vol.19 No.2

Arthroscopic treatment has been reported to provide effective improvement of ankle function when used in treatment of small osteochondral lesion of talus; however, favorable long-term results have been less predictable for large osteochondral lesion of talus. In cases in which primary arthroscopic treatment fails, the decision regarding which subsequent technique to choose has become increasingly difficult, as good clinical outcomes may be unlikely for such patients irrespective of the surgical technique used. Redomicrofracture should be used judiciously for treatment of osteochondral lesion of talus in which arthroscopic treatment has failed.

히터 일체형 하이브리드 단판형 플라즈마 방전소자

최우진,최은혜,성형석,권진구,이성의,Choi, Woo Jin,Choi, Eun Hye,Sung, Hyeong Seok,Kwon, Jin Gu,Lee, Seong Eui 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.4

Recently, the application of atmospheric plasma technology in air filtration is increasing. Sterilization by an atmospheric plasma device is very effective. However, ozone gas, which is generated during atmospheric plasma formation, poses a hazard to human health. To reduce the ozone gas during plasma discharge, we fabricated a one-plate hybrid plasma discharge device with a heating element, which can decompose ozone gas effectively by a simple heating action. In this study, we evaluated the plasma discharge characteristics and ozone concentrations with various Ar flow rates and temperatures. With increasing Ar gas flow rate, the ozone concentration and spectrum intensity increased till an Ar gas flow rate of 60 sccm, and decreased thereafter. When discharged in high temperature, the ozone concentration and spectrum intensity decreased. Further, to evaluate the state of the treated surface under various plasma discharge and heating conditions, we measured the variation in the contact angles on the surface. Regardless of the temperature, the contact angle increased with increasing discharge voltage. However, the contact angle increased when discharged at high temperature.

디지털 방식의 인접면 접촉강도 측정장치의 개발 및 평가

최우진,김경화,김진아,강동완,오상호,Choi, Woo-Jin,Kim, Kyung-Hwa,Kim, Jin-A,Kang, Dong-Wan,Oh, Sang-Ho 대한치과보철학회 2007 대한치과보철학회지 Vol.45 No.5

Statement of problem: The proper contact relation between adjacent teeth in each arch plays an important role in the stability and maintenance of the integrity of the dental arches. Proximal contact has been defined as the area of a tooth that is in close association, connection, or touch with an adjacent tooth in the same arch. Purpose: The aim of this study was to develop a digital device for measuring the proximal tooth contact tightness by pulling a thin stainless steel strip (2mm wide, 0.03mm thick) inserted between proximal tooth contact. Material and method: This device consists of measuring part, sensor part, motor part and body part. The stainless steel strip was connected to a stain gauge. The strain gauge was designed to convert the frictional force into a compressive force. This compressive force was detected as a electrical signal and the electrical signal was digitalized by a A/D converter. The digital signals were displayed by a micro-processor. The pulling speed was 8mm/s. Results: For testing reliability of the device in vivo, two healthy young adults (A, B) participated in this experiment. The tightness of proximal tooth contact between the second premolar and the first molar of mandible (subject A) and maxilla (subject B) was measured fifteen times for three days at rest. We double-checked the accuracy of the device with a Universal Testing Machine. Output signals from the Universal Testing Machine and the measuring device were compared. Regression analysis showed high linearity between these two signals. In vivo test, no significant differences were found between measurements. Conclusion: This device has shown to he capable of producing reliable and reproducible results in measuring proximal tooth contact. Therefore, it was considered that this device was appropriate to apply clinically.

Ad-hoc 망에서 이동 노드 간 상호 인증

최우진,석경휴,Choi, Woo-Jin,Seok, Gyeong-Hyu 한국전자통신학회 2015 한국전자통신학회 논문지 Vol.10 No.10

인터넷의 급속한 성장으로 무선망 사용에 대한 요구가 다양해 졌으며, 시간과 공간의 제한을 받지 않는 새로운 차원의 인터넷 기술인 Ad-hoc망이 필요하게 되었다. Ad-hoc망은 기지국 중심의 통신을 하지 않으며, 망에 포함된 각 이동 노드들이 서로 중계국 역할을 하여 통신한다. 최근 몇 년 동안 Ad-hoc망에서의 다양한 라우팅 프로토콜 및 무선 네트워크의 보안, 인증 방법에 대한 연구가 활발히 진행 중에 있지만, 무선인터넷 및 Ad-hoc망에서의 보안, 인증은 미비한 실정이다. 본 논문에서는 USIM 카드에 인증 및 키일치 기술 적용 가능성을 고려한 자바카드와 Ad-hoc망의 DSR 라우팅 프로토콜을 이용하여 이동노드간의 안전한 인증 메커니즘을 제안하였다. It was diversified demand for a wireless network to the rapid growth of the Internet, the time and space that are not in the new level of Internet technology, limits the Ad-hoc networks are needed. Ad-hoc networks do not communicate with the central station, each of the mobile nodes included in the network communicate with each other by the relay role. In recent years, the Ad-hoc wireless networks in a variety of routing protocols and network security, research is actively underway for the authentication method, but the security of wireless Internet and Ad-hoc networks, certification is incomplete situation. This paper considers the authentication and key agreement technique applicability of the USIM card using the DSR routing protocol of the Java Card and Ad-hoc networks, we propose a secure authentication mechanism between the mobile node.

연료전지 시스템을 이용한 Line-Interactive 방식의 무정전 전원 공급 장치의 설계

최우진,전희종,Choi, Woo-Jin,Jeon, Hee-Jong 한국조명전기설비학회 2004 조명·전기설비학회논문지 Vol.18 No.6

본 논문에서는 연료전지와 컨버터 모듈을 채용한 1-[KVA] 용량의 Line-interactive방식의 무정전 전원 공급장치(UPS)가 제안된다. 제안된 시스템은 두 개의 500[W]급 양자 교환막형 연료전지에 DC/DC 컨버터가 결합된 모듈을 채용하며, 이 모듈들이 인버터의 DC-Link를 공유한다. DC-Link에는 슈퍼커패시터 모듈이 채용되어 출력의 변동이나 연료 개질기의 느린 동특성으로 인한 연료전지와 부하 사이의 순시적인 전력의 불균형을 개선시킨다. 또한 슈퍼커패시터에 저장된 에너지는 단시간 동안의 과부하를 처리할 때에도 사용될 수 있다. 제안된 시스템은 배터리를 사용하지 않으므로 환경친화적이며 청정 에너지원에 대한 요구를 만족시킨다. 1-[KVA] 시스템의 설계 예가 제시되며, 1시간의 정전동안 부하에 전력을 공급하기 위해 필요한 수소의 양과 보상용 슈퍼커패시터의 용량을 계산하는 방법이 소개된다. In this paper the design of a 1-[KVA] fuel cell powered line-interactive UPS system employing modular (fuel cell & DC/DC converter) blocks is proposed. The proposed system employs the two fuel cell modules along with suitable DC/DC converters and these modules share the DC-Link of the DC/AC inverter. A supercapacitor module is also employed to compensate for the instantaneous power fluctuations and to overcome the slow dynamics of the fuel processor. The energy stored in the supercapacitor can also be utilized to handle the overload conditions for a short time period. Due to the absence of batteries, the system satisfies the demand for an environmentally friendly and dean source of the energy. A complete design example illustrating the amount of hydrogen storage required for 1hr power outage, and sizing of supercacpacitor for transient load demand is presented for a 1-[KVA] UPS.

La₂O₃ 첨가에 따른 BaTiO₃의 미세구조 및 유전특성

최우진,문경석,Choi, Woo-Jin,Moon, Kyoung-Seok 한국결정성장학회 2020 韓國結晶成長學會誌 Vol.30 No.3

The effect of La₂O₃ addition on the crystalline phase, microstructure, and dielectric properties of BaTiO₃ has been studied as a function of the amounts of La₂O₃. 0.3 mol% TiO₂-excess BaTiO₃ powder was synthesized by solid-state reaction, and then the powder compacts with various amounts of La₂O₃ were sintered at 1250℃ for 2 hours. Room temperature XRD showed changes in the lattice parameters and a decrease of tetragonality (c/a) as the amounts of La₂O₃ increased. It can be explained that the phase transition from tetragonal to cubic phase occurred because La³⁺ replaced Ba²⁺ site, which increased the instability of the tetragonal phase. As La₂O₃ was added over 0.1 mol%, the critical driving force for growth (Δg_c) increased over maximum driving force (Δg_max). As the result, the grain size decreased with La₂O₃ addition. Dielectric constant decreased as the amounts of La₂O₃ increased, which was analyzed with crystal structure and microstructure. La₂O₃ 첨가량에 따른 결정상 및 미세구조 변화와 유전특성과의 상관관계에 대해 연구하였다. 고상반응법을 이용해 합성된 0.3 mol% TiO₂ 과잉 BaTiO₃ 분말에 대해 La₂O₃ 첨가량을 다르게 첨가하여 1250℃에서 2시간 동안 소결되었다. 상온에서 측정된 XRD는 La₂O₃ 첨가량이 증가함에 따라 lattice parameter가 변화하였고, 정방정비가 감소하였다. 이는 La³⁺가 Ba²⁺ 자리에 치환되어 정방정상의 불안정성을 높여 입방정상으로 상전이 된 것으로 설명할 수 있다. La₂O₃ 첨가량이 증가할 때, 임계입자성장구동력(Δg_c)이 최대 입자성장구동력 (Δg_max)보다 높아져, 입자크기와 밀도가 감소하였다. 유전상수는 La₂O₃가 증가함에 따라 감소하였는데, 이를 결정상 및 미세구조의 변화에 대한 효과로 분석하였다.

양자 교환막형 연료전지의 등가 임피던스 모델을 이용한 인버터에 의한 맥동 전류의 영향에 관한 연구

최우진,Choi, Woo-Jin 한국조명전기설비학회 2004 조명·전기설비학회논문지 Vol.18 No.6

본 논문에서는 인버터에서 발생하는 맥동전류가 양자 교환막형 연료전지에 미치는 영향을 임피던스 모델을 통하여 분석한다. 제안된 방법은 주파수 응답 분석법을 이용하여 연료전지 스택의 등가 임피던스를 유도하고, 유도된 모델을 이용하여 맥동전류의 영향을 분석한다. 모델을 통해 계산된 결과는 상용 연료전지 스택을 사용한 실험을 통하여 증명된다. 실험결과는 인버터에 의해 발생한 맥동전류로 인해 최대 10(%)까지 연료전지 스택의 출력이 감소할 수 있음을 보인다. In this paper the effects of inverter ripple currents to the Proton Exchange Membrane Fuel Cell Stack (PEMFCS) is analyzed by the impedance model. The proposed method employs the frequency analysis technique to derive an equivalent impedance model of the fuel cell stack and the effects of the inverter ripple current are investigated. The calculated results m then verified by means of experiments on commercially available PEMFCSs. The experimental results show that the ripple current can contribute up to 10[%] reduction in the available output power.

스크린 프린터에 의한 광캐패시터용 카본 전극 제작

최우진(Woo-Jin Choi),곽동주(Youl-Moon Sung),성열문(Dong-Joo Kwak),하순호(Soon-Ho Ha) 한국조명·전기설비학회 2009 한국조명·전기설비학회 학술대회논문집 Vol.2009 No.10월