마그네토스트릭션 센서 바이어스 자기계의 요크 위상최적설계

김우철(Woochul Kim),김윤영(Yoon Young Kim) 대한기계학회 2002 대한기계학회 기타 간행물 Vol.2002 No.11

원발 혹은 재발성 비소세포 폐암 환자에서 사이버나이프를 이용한체부 방사선 수술의 치료 결과

김우철(Woochul Kim),김헌정(Hun-Jung Kim),박정훈(Jeong Hoon Park),허현도(Hyun Do Huh),최상현(Sang Huoun Choi) 대한방사선종양학회 2011 Radiation Oncology Journal Vol.29 No.1

목 적: 초기 비소세포성 폐암 환자에서 수술적 절제 이외의 국소 치료로 최근 방사선 수술의 사용이 늘고 있다. 이에 저자들은 초기 혹은 재발한 비소세포성 폐암 환자를 대상으로 시행한 체부 방사선 수술의 치료 결과를 분석하여 그 유용성을 알아 보고하고자 한다. 대상 및 방법: 비소세포성 폐 종양에 대하여 방사선 수술이 시행되었던 24명의 환자, 28 lesion에 대하여 후향적 분석을 시행하였다. 이 중 원발성 종양은 19명, 재발한 환자는 5명이었고 재발한 환자 5명 중 3명이 이전 치료 부위에서 재발한 환자 이었다. 원발성 종양 19명 중에서 4명은 외부 방사선 치료 후 추가로 방사선 수술을 시행 받았다. 24명의 초기 병기는 IA, IB, IIA, IIB, IIIA, IIIB, IV가 각각 7, 3, 2, 2, 3, 1, 6명이었고, 방사선 수술 당시의 T 병기는 T1 lesion이 13곳, T2가 12곳, T3가 3곳이었다. 방사선 수술은 6 MV X-ray를 이용하였고 planning target volume1 (PTV1)에 총 방사선량 15∼60 Gy (median, 50 Gy)를 3회 혹은 5회에 걸쳐 처방하여 시행하였다. 중앙 추적관찰기간은 469일이었다. 결 과: 28곳의 GTV는 0.7∼108.7 mL (median, 22.9 mL)이었고, PTV1은 5.3∼184.8 mL (median, 65.4 mL)이었다. 3개월 반응률은 complete response (CR) 14곳, partial response (PR) 11곳, stable disease (SD) 3곳이었고, 마지막 추적에서의 치료반응은 CR 13곳, PR 9곳, SD 2곳, progressive disease (PD) 4곳이었다. 원발종양으로 초기 병기 IA, IB 10명에서는 50일만에 1명이 폐렴으로 사망하였고, 1명이 국소재발 하였으나 나머지 환자는 6개월에서 2년 간 국소재발 없이 추적관찰 되고 있으며, IIA-IIB 환자는 4명으로 환자 수가 적어서 뚜렷한 결론을 내리기 어려웠고, 재발성 폐암 환자 5명을 포함하는 10명의 IIIA-IV 병기에서는 사망 3명, 국소재발 1명, loco-regional failure 1명, regional failure 2명으로 좋지 않은 치료 결과를 보였다. 이 중에서 방사선 수술을 시행한 장소에서 재발한 경우는 총 28 lesion 중 4곳으로 85.8%의 국소제어율을 보였다. 방사선치료 양은 biologically equivalent dose (BED) 100Gy10 이하인 8 lesion 중에서 3 lesion에서 국소 재발하여 100 Gy10 이상인 20 lesion 중에서는 1 lesion에서만 재발한 경우보다 나빴다. 또한 중앙부의 종양과 방사선수술 당시의 병기가 T2 이상인 경우가 재발이 많았다. 결 론: 비소세포성 폐암환자에서 사이버나이프를 이용한 체부 방사선 수술은 부작용이 적으면서 높은 국소제어율을 얻을 수 있는 치료이며, 주변부의 T1 병기의 폐암에 대해서 BED 100 Gy10 이상의 방사선 치료가 국소제어율을 높이는데 도움이 된다고 생각된다. Purpose: Recently, the use of radiosurgery as a local therapy in patients with early stage non-small cell lung cancer has become favored over surgical resection. To evaluate the efficacy of radiosurgery, we analyzed the results of stereotactic body radiosurgery in patients with primary or recurrent non-small cell lung cancer. Materials and Methods: We reviewed medical records retrospectively of total 24 patients (28 lesions) with non-small cell lung cancer (NSCLC) who received stereotactic body radiosurgery (SBRT) at Inha University Hospital. Among the 24 patients, 19 had primary NSCLC and five exhibited recurrent disease, with three at previously treated areas. Four patients with primary NSCLC received SBRT after conventional radiation therapy as a boost treatment. The initial stages were IA in 7, IB in 3, IIA in 2, IIB in 2, IIIA in 3, IIIB in 1, and IV in 6. The T stages at SBRT were T1 lesion in 13, T2 lesion in 12, and T3 lesion in 3. 6MV X-ray treatment was used for SBRT, and the prescribed dose was 15∼60 Gy (median: 50 Gy) for PTV1 in 3∼5 fractions. Median follow up time was 469 days. Results: The median GTV was 22.9 mL (range, 0.7 to 108.7 mL) and median PTV1 was 65.4 mL (range, 5.3 to 184.8 mL). The response rate at 3 months was complete response (CR) in 14 lesions, partial response (PR) in 11 lesions, and stable disease (SD) in 3 lesions, whereas the response rate at the time of the last follow up was CR in 13 lesions, PR in 9 lesions, SD in 2 lesions, and progressive disease (PD) in 4 lesions. Of the 10 patients in stage I, one patient died due to pneumonia, and local failure was identified in one patient. Of the 10 patients in stages III-IV, three patients died, local and loco-regional failure was identified in one patient, and regional failure in 2 patients. Total local control rate was 85.8% (4/28). Local recurrence was recorded in three out of the eight lesions that received below biologically equivalent dose 100 Gy10. Among 20 lesions that received above 100 Gy10, only one lesion failed locally. There was a higher recurrence rate in patients with centrally located tumors and T2 or above staged tumors. Conclusion: SBRT using a CyberKnife was proven to be an effective treatment modality for early stage patients with NSCLC based on high local control rate without severe complications. SBRT above total 100 Gy10 for peripheral T1 stage patients with NSCLC is recommended.

Magnetostrictive Grating with an Optimal Yoke for Generating High-Output Frequency-Tuned SH Waves in a Plate

Woochul Kim(김우철),Ik Kyu Kim(김익규),Yoon Young Kim(김윤영) 한국소음진동공학회 2007 한국소음진동공학회 학술대회논문집 Vol.2007 No.3

나노구조물 첨가를 이용한 고온에서의 고체 열전도도 감소

김우철(Woochul Kim),김강민(Kangmin Kim),박준영(Junyoung Park),Suzanne L. Singer,Arun Majumdar,Dmitri Klenov,Arthur C. Gossard,Susanne Stemmer,Joshua M. O. Zide 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Thermal conductivity of a crystalline solid at high temperature is dominated by the Umklapp process because the number of high frequency phonons increases as with temperature. It is challenging to reduce the thermal conductivity of crystalline solids at high temperature although it is widely known that by increasing the atomic defect concentration, thermal conductivity of crystalline solids can be reduced at low temperature. By increasing the concentration of ErAs nanoparticles in In0.53Ga0.47 As up to 6 atomic percent, we demonstrate a thermal conductivity reduction by almost a factor of three below that of In0.53Ga0.47 As at high temperature. A theoretical model suggests that the mean free path of the low frequency phonons is suppressed by increasing the ErAs nanoparticle concentration.

IB MYP의 아이디어에 기반한 학교 민주시민교육 개선 방안 탐색

김우철 ( Woochul Kim ),강현석 ( Hyeonsuk Kang ) 한국교육과정학회 2021 교육과정연구 Vol.39 No.3

The purpose of this study is to review the characteristics and limitations of democratic citizenship education in the 2015 revised curriculum and to present a new approach to school democratic citizenship education that utilizes the compositional ideas(or concepts) of the International Baccalaureate Middle Years Programme (IB MYP). We considered the approach to democratic citizenship education defined in the 2015 revised curriculum to identify problems, and then proposed ways to improve it based on the three compositional ideas of the IB MYP. The three proposed improvements are as follows. First, based on the “subject-group overviews” idea, the contents system table in the Korean curriculum documents was reconstructed to ensure consistency and clarity in curriculum design. Second, with reference to the “action through service” idea, services were conducted after democratic citizenship education classes and reflection journals were completed so that learning could be achieved through experience. Third, based on the “interdisciplinary learning” idea, the integrated education method was devised so that the current cross-curricular learning in operation could be more effective. Lastly, we proposed recommendations for enhancing instruction and the assessment of curriculum development.

Coil Configuration Design using the Topology Optimization : Applications to Optical Pickup Actuator

Woochul Kim(김우철),Jae Eun Kim(김재은),Yoon Young Kim(김윤영) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.10

The objective of this research is to develop a method optimizing the coil configuration for the maximum Lorentz force in a given direction, and the minimum Lorentz forces and torques in other directions. To achieve this objective, topology optimization of coil configuration is set up. Unlike the existing application of the topology optimization method in coil design which can handle a fixed-direction current density field only, the proposed topology optimization approach is capable of dealing with varying current density magnitudes and directions. The varying field must be considered for the Lorentz force maximization problem. The effectiveness of the proposed formulation has been checked by comparing an optimal coil configuration with the existing fine-pattern coil commercially available.

열전소자를 이용한 적외선 방사량 감소 기술에 관한 연구

김훈(Hoon Kim),김교민(Kyomin Kim),김우철(Woochul Kim) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.3

열전소자를 이용하여 고온의 표면을 능동적으로 냉각하여 적외선 방사량을 줄이는 기술을 소개한다. 공력가열이나 자체 발열 등에 의한 고온 표면 환경을 구현하였고, 여기에 열전소자를 설치하여 냉각하였을 때의 표면 온도와 적외선 방사량을 상용 수치해석 소프트웨어를 사용하여 계산하였다. 이를 통해 특정 환경에서 열전냉각소자를 이용하여 고온 표면에 있어 외부 환경과 비교했을 때의 적외선 방사량 대비를 이론적으로 완전히 제거할 수 있음을 확인하였다. We introduced a technology for reducing infrared radiation through the active cooling of hot surfaces by using a thermoelectric refrigerator. Certain surfaces were heated by aerodynamic heating, and the heat generation processes are proposed here. We calculated the temperatures and radiations from surfaces, while using thermoelectric refrigerators to cool the surfaces. The results showed that the contrast between the radiations of certain surfaces and the ambient environments can be removed using thermoelectric refrigerators.

Optimal Design of the Optical Pickup Actuator Coil

Yoon Young Kim(김윤영),Woochul Kim(김우철),Jae Eun Kim(김재은) 한국소음진동공학회 2004 한국소음진동공학회 학술대회논문집 Vol.2004 No.5

홈 형태의 전극을 이용한 열전소자의 기계적인 강도 개선

김교민(Kyomin Kim),김훈(Hoon Kim),김우철(Woochul Kim) 대한기계학회 2018 大韓機械學會論文集B Vol.42 No.4

열전소자는 에너지 변환장치의 한 종류로 특히 폐열을 이용하여 전기를 생산해 낼 수 있는 장치로 각광받고 있다. 열전소자는 열전성능지수가 높음과 동시에 기계적인 강도가 높을수록 좋은 성능을 낼 수 있다. 본 연구에서는 열전소자의 기계적인 강도를 개선하기 위해 접착 강도에 취약한 기존의 평판 형태의 전극이 아닌 홈 형태의 전극을 소개한다. 평판 형태의 전극과 홈 형태의 전극은 Ag 페이스트를 이용하여 열전소재와 부착하였다. 각각의 열전소재가 부착된 전극은 인장 강도와 전단 강도를 만능시험기로 접착 강도를 측정하였다. 이를 통해 기존의 평판 형태의 전극보다 홈 형태의 전극을 사용하였을 때 더 높은 접착 강도를 나타내는 것을 확인하였다. 또한 열-전기 수치해석 프로그램을 이용하여 기존 평판 형태의 전극과 홈 형태의 전극을 사용하여 모델링 한 소자의 성능 차이를 확인하였다. Thermoelectric modules are energy conversion devices. They are attracting attention as a devices capable of producing electricity by utilizing waste heat. Thermoelectric modules require a high zT, and mechanical stability for reliable operation. In this research, we introduce the groove-type electrode to improve mechanical stability. Each electrode is attached to the thermoelectric element using a silver paste. The tensile and the shear strength of the thermoelectric materials’ electrodes are measured using a universal testing machine. Results show that the groove-type electrode has higher bonding strength than the flat-type electrode. We also confirmed the difference in the performance of the element modeled using flat- and groove-type electrodes for thermo-electric numerical analysis.

카메라 셔터 장치에 이용되는 자기 회로의 위상최적화

김지훈(Jihun Kim),김우철(Woochul Kim),김윤영(Yoon Young Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

This investigation is concerned with the topology optimization of a magnetic circuit producing torque in a camera shutter device. Since the induced magnetic torque operates shutter movement, the torque maximization for a given input current is an important issue. To achieve this goal, a system of a yoke and a permanent magnet is designed by a topology optimization method. In order to formulate the topology optimization process, Coulomb virtual work method is employed for the magnetic torque calculation. The torque profile by the optimized magnetic circuit is compared with the torque profile of a nominal magnetic circuit.