상‧ 하둔동맥 천공지피판을 이용한 대전자부 욕창의 치료

탁우현,이원재,윤인식,나동균 대한성형외과학회 2011 Archives of Plastic Surgery Vol.38 No.3

Purpose: Management of pressure sores has been improved, along with development of musculocutaneous flaps and perforator flaps. Nowadays, the treatment of pressure sore with perforator flaps has shown several advantages, including minimal donor site morbidity, relatively versatile flap design not only in primary cases but also in recurred cases and minimized anatomical rearrangement of regional muscle position. In this study, we report our clinical experience of gluteal perforator flap used in the treatment of a greater trochanteric pressure sore. Methods: A clinical study was performed on 7 patients who underwent total 10 operations. 1 superior gluteal artery perforator flap and 9 inferior gluteal artery perforator flaps were used to reconstruct the defect, followed by the mean observation duration of 22 months. Results: There were no total flap loss. We treated 2 cases of partial flap loss with debridement and primary repair. 2 recurred cases were successfully treated using the same method. Donor sites were all primarily repaired. Conclusion: The gluteal perforator flap could be considered as a safe and favorable alternative in the treatment of soft tissue defects in the greater trochanteric area. The advantages of the flap include low donor site morbidity and the possibility of versatile flap design not only in primary cases but also in recurred cases.

멀티데이터베이스에서 XML을 이용한 스키마 통합

탁우현(Tak Woohyeon),류영호(Ryu Youngho),이종환(Lee Jonghwan),김경석(Kim Kyongsok) 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.2Ⅰ

멀티데이터베이스를 구축하기 위해서는 전역스키마 (global schema) 구축이 필수적이며, 지역스키마 (local schema) 간 충돌 해결과 스키마 통합 정보는 질의 처리 및 질의 결과를 사용자에게 보여주기 위해 필요하다. 전역스키마 생성 및 충돌 해결 방법은 많이 연구가 되어 왔다. 하지만, 스키마 통합을 위한 정보가 어떻게 표현되고, 어떻게 사용되는지에 대한 연구는 부족하다. 본 논문에서는 지역 스키마와 전역스키마를 XML DTD 및 XML 문서로 표현하고, 이를 이용하여 멀티데이터베이스를 위한 스키마 통합 방법을 제안한다. 스키마 통합 정보와 멀티데이터베이스와 지역데이터베이스들간 데이터 교환을 XML을 이용함으로써 이기종간 데이터 교환이 쉽고 멀티데이터베이스 시스템의 확장 및 다른 시스템으로의 전환이 용이하게 된다.

Sb가 결핍된 N형 Skutterudite Co4Sb12의 열전 특성

탁장렬,Nguyen Van Du,정민석,이나영,남우현,서원선,조중영 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.6

In this study, we investigate the effect of an Sb-deficiency on the thermoelectric properties of double-filled n-type skutterudite (In0.05Yb0.15Co4Sb12-x). Samples were prepared by encapsulated induction melting, consecutive long-time annealing, and finally spark plasma sintering processes. The Sb-deficient sample contained a CoSb2 secondary phase. Both the double-filled n-type skutterudite pristine and Sb-deficient samples showed metallic behavior in electrical conductivity with increasing temperature. The carrier concentration of the Sb-deficient sample decreased compared with that of the pristine sample. Due to a decrease in carrier concentration, the Sb deficient sample showed decreased electrical conductivity and an increased Seebeck coefficient compared with the conductivity and coefficient of the pristine sample. Furthermore, the Sb deficient sample showed an increase in the power factor (σ⋅S2); the power factor maximum shifted to athe lower temperature side than ones of the pristine sample. As a result, the Sb-deficient sample represents an improved average figure of merit (ZT) and a ZTmax temperature lower than that of the pristine sample. Therefore, we propose that Sb-deficient double-filled n-type skutterudite thermoelectric material (In0.05Yb0.15Co4Sb12-x) be used in the 573~673 K temperature range. 본 연구는 이중 충진 된 n 형 Skutterudite에서 Sb 결핍 조성을 합성하여 열전 특성을 알아보았다. 밀폐유도용해 및 스파크 플라즈마 소결 공정에 의해 샘플을 제조 하였다. 이중 충진 된 n 형 skutterudite pristime 샘플과 Sb가 결핍된 샘플은 모두 온도가 증가함에 전도도가 낮아지는 금속 거동의 전기 전도성을 보여 주었다. 또한, 캐리어 농도 감소로 진성 반도체의 영향이 더 낮은 온도 대역부터 나타났으며, 이러한 결과로 파워 펙터의 최대치는 증가하고, 파워 펙터 최대치의 온도 또한 낮아졌다. 열전도도는 소폭 감소하였으며, 이로 인한 열전 성능 지수 (ZT)가 평균적으로 증가하였다. 결과적으로, Sb 결핍 샘플은 pristine 샘플 보다 평균 성능 지수 (ZT) 를 향상시켰고, ZTmax 온도를 낮추었다. 우리는 본 연구를 통하여, 573 K ~ 673 K 온도 범위에서 사용할 열전 재료로 Sb 결핍된 n형 CoSb3 를 제안한다.

Sb가 결핍된 N형 Skutterudite Co₄Sb₁₂의 열전 특성

탁장렬,정민석,이나영,남우현,서원선,조중영,Tak, Jang-Yeul,Van Du, Nguyen,Jeong, Min Seok,Lee, NaYoung,Nam, Woo Hyun,Seo, Won-Seon,Cho, Jung Young 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.6

In this study, we investigate the effect of an Sb-deficiency on the thermoelectric properties of double-filled n-type skutterudite ($In_{0.05}Yb_{0.15}Co_4Sb_{12-x}$). Samples were prepared by encapsulated induction melting, consecutive long-time annealing, and finally spark plasma sintering processes. The Sb-deficient sample contained a $CoSb_2$ secondary phase. Both the double-filled n-type skutterudite pristine and Sb-deficient samples showed metallic behavior in electrical conductivity with increasing temperature. The carrier concentration of the Sb-deficient sample decreased compared with that of the pristine sample. Due to a decrease in carrier concentration, the Sb deficient sample showed decreased electrical conductivity and an increased Seebeck coefficient compared with the conductivity and coefficient of the pristine sample. Furthermore, the Sb deficient sample showed an increase in the power factor (${\sigma}{\cdot}S^2$); the power factor maximum shifted to athe lower temperature side than ones of the pristine sample. As a result, the Sb-deficient sample represents an improved average figure of merit (ZT) and a $ZT_{max}$ temperature lower than that of the pristine sample. Therefore, we propose that Sb-deficient double-filled n-type skutterudite thermoelectric material ($In_{0.05}Yb_{0.15}Co_4Sb_{12-x}$) be used in the 573~673 K temperature range.

Dual cortical tunneling method for endoscopic forehead lift

김미정,이나라,탁우현,이원재,노태석,백우열 대한미용성형외과학회 2022 Archives of Aesthetic Plastic Surgery Vol.28 No.3

Background Endoscopic forehead lift with cortical tunneling is an effective option for rejuvenation of the upper third of the face. Although it has been considered safe and reliable, with relatively consistent long-term results, relapse and weakening of adhesion have been common problems. Methods We suggest the dual-tunneling method for overcoming these limitations. A total of 100 patients aged 17 to 65 years underwent forehead lifting with cortical tunneling by the senior author from August 2016 to December 2017. The single-tunnel method was applied in one half of the patients and the dual-tunnel method in the other half. Bilateral brow positions were measured immediately following surgery and 6 months later. Results For all cases, cortical tunneling was done at the central incision and both paramedian incisions; therefore, three tunnels were used in the control group and six tunnels in the experimental group. In the single-tunnel group, relapse distances were 2.39±0.83 mm for the medial brow and 3.26±0.91 mm for the lateral brow (6 months postoperatively; n=100). The dual-tunnel group showed significantly smaller (P<0.001) relapse distances, with values of 1.69±0.46 mm and 2.17±0.59 mm for the medial and lateral brow, respectively (6 months postoperatively; n=100). The experimental group did not show an increase in complications. Conclusions The dual-tunneling method, designed to minimize the cheese-wiring effect, uses a triangular plane to avoid a focal fixation. The fixation also includes the periosteum to hold the forehead tissue in place, inducing stronger adhesion.

딸기시설재배를 위한 말벌퇴치기반 온실 모니터링 시스템

문미경(Moon Mee Gyung),탁우현(Tak Woo Hyun),곽효진(Kwak Hyo Jin) 한국HCI학회 2017 한국HCI학회 학술대회 Vol.2017 No.2

매트랩/시뮬링크 simulation model을 이용한 열전 모듈의 효율 예측

이나영,예성욱,Rahman Jamil Ur,탁장렬,조중영,서원선,신원호,Walter Commerell,남우현,노종욱 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.11

Development new high-performance thermoelectric materials for more efficient power generation systems and eco-friendly refrigerating systems has been challenging. Over the past few decades, thermoelectric studies have been focused on increasing the thermoelectric properties of materials. However, for conventional applications, developing of thermoelectric devices or modules with lower cost and simpler fabrication processes is also important. Simulation models that can predict the thermoelectric efficiency of modules using the thermoelectric properties of materials are needed for this purpose. In this study, we developed a simple model for calculating the efficiency of thermoelectric modules using MATLAB/Simulink. In this model, the temperature difference between the hot source and heat sink was fixed to ensure the precise comparisons of thermoelectric efficiency. The electric resistivity and Seebeck coefficient of thermoelectric materials was used in order to predict the efficiency of the thermoelectric modules. Then, the efficiency of the thermoelectric modules was verified using measured values which had been reported in prior experimental works. In this study, the simulated values were higher than the real thermoelectric effiency values. To address this, the simulations should consider the thermal resistance or electric contact resistance between the thermoelectric materials and electrodes.

Grain 크기 조절을 통한 n-Type Bi2Te3 열전 소재 특성 향상

이나영,예성욱,Rahman Jamil Ur,탁장렬,조중영,서원선,신원호,남우현,노종욱 한국마이크로전자및패키징학회 2021 마이크로전자 및 패키징학회지 Vol.28 No.4

The enhancement of thermoelectric figure of merit was achieved by the simple processes of sieving and high energy ball milling, respectively, which are enable to reduce the grain size of n-type Bi2Te3 thermoelectric materials. By optimizing the grain size, the electrical conductivities and thermal conductivities were controlled. In this study, spark plasma sintering was employed for hindering the grain growth during the sintering process. The thermoelectric figure of merit was measured to be 0.78 in the samples with 30 min high energy ball milling process. Notably, this value was 40 % higher than that of pristine Bi2Te3 sample. This result shows the properties of thermoelectric materials can be readily controlled by optimization of grain size via simple ball milling process. 본 연구에서는 체가름과 고에너지 볼 밀링 공정이 n-type Bi2Te3 열전 재료의 전기적 및 열적 수송 특성에 미치는 영향을 검토하였다. 입자 크기가 감소한 분말의 특성을 유지하기 위하여 짧은 시간 안에 소결이 가능한 방전 플라즈마 소결 공정 (spark plasma sintering, SPS)을 진행하였다. 그 결과, 밀링 처리를 진행한 소결체의 열전 성능지수가 향상되었으며, 30분동안 고에너지 볼 밀링 공정을 거친 샘플이 425 K에서 0.78의 최대 열전 성능지수를 가지는 것을 확인하였다. 이는 손쉬운 공정을 이용하여 결정립 크기 감소를 통한 phonon의 격자 산란을 효과적으로 유도한 결과이다. 동시에 n-type Bi2Te3에서 anti-site defect와 같은 결함을 제어함으로써 캐리어 농도를 증가시킬 수 있음을 본 연구를 통하여 확인하였다.

컬러 분포를 가중치로 이용한 계층적 컬러 클러스터링에 관한 연구

윤위영(Yun Weyoung),범수균(Beum Soogyun),탁우현(Tak Woohyun),이종환(Lee Jonghwan),김경석(Kim Kyongsok) 한국정보과학회 1998 한국정보과학회 학술발표논문집 Vol.25 No.2Ⅰ

내용기반 이미지 검색 (Content-based image retrieval)에서 컬러 특징을 표현하기 위해 컬러 히스토그램이 많이 이용되고 있다. 하지만 히스토그램의 고차원적인 성질 때문에 색인구조를 사용한 효율적인 검색이 어렵고, 유사도 계산 단계에서 비용이 많이 든다. 이점을 개선하기 위해서 이미지의 컬러 정보 손실을 최소화하면서 히스토그램의 차원을 낮추는 컬러 클러스터링 방법에 제안되었다. 이 논문은 이미지 검색의 응용 분야에 따른 이미지 데이터의 컬러 분포 특성을 이용한 컬러 클러스터링 방법을 제안한다. 컬러 분포를 가중치로 이용한 계층적 컬러 클러스터링 방법에 대해 알아보고, 두 단계 컬러히스토그램을 이용한 이미지 검색에 적용하여 컬러 정보 유지 능력을 실험해 본다.