철계 형상기억합금을 이용한 콘크리트 기둥의 전단보강 실험연구

정동혁,정새벽,최재희,김근오 한국지진공학회 2024 한국지진공학회논문집 Vol.28 No.1

The current study investigates the seismic performance of shear-dominant RC columns retrofitted with iron-based shape memory alloy (Fe SMA). Three RC columns with insufficient transverse reinforcement were designed and fabricated for lateral cyclic loading tests. Before testing, two specimens were externally confined with carbon fiber-reinforced polymer (CFRP) sheets and self-prestressed Fe SMA strips. The test results showed that both CFRP and Fe SMA performed well in preventing severe shear failure exhibited by the unretrofitted control specimen. Furthermore, the two retrofitted specimens showed ductile flexural responses up to the drift ratios of ±8%. In terms of damage control, however, the Fe SMA confinement was superior to CFRP confinement in that the spalling of concrete was much less and that the rupture of confinement did not occur.

PTW-LinaCheck 측정기의 선량 특성과 일일 출력측정 응용에 관한 연구

정동혁,이강규,문언철,김현진,김영석,문성록,Jeong, Dong-Hyeok,Lee, Kang-Kyoo,Moon, Un-Chul,Kim, Hyun-Jin,Kim, Young-Seok,Moon, Sun-Rock 한국의학물리학회 2008 의학물리 Vol.19 No.1

본 연구에서는 선형가속기 출력 검출용으로 상용화된 PTW-LinaCheck의 선량 특성을 조사하고 임상적 응용에 관하여 논의하고자 한다. 본 연구에서는 6, 15MV광자선 및 4, 6, 9, 12, 16 MeV전자선에 대하여 측정값의 재현성, 선형성, 선량률 의존성을 조사하였다. 또한 측정값의 오차범위를 조사하기 위하여 일일 점검 시 검출기의 셋업의 기하학적 오차에 의한 측정값의 변화를 조사하였다. 본 측정의 결과로서 일일 측정 시 셋업 오차에 의한 측정값의 변화는 재현성을 포함하여 ${\pm}0.6%$ 이내로 평가되었다. 이 때 선형성과 선량률 의존성에 의한 오차는 무시할 정도였다. 이를 통하여 LinaCheck는 선량 특성과 편리한 셋업의 관점에서 양호한 것으로 결론을 내렸다. 아울러 본 논문에서는 본 검출기를 사용한 60여 일간의 임상적 적용 사례도 제시하였다. In this study, we have investigated the dose characteristics of PTW-LinaCheck designed to detect output of medical LINAC and discussed clinical use of the detector. The reproducibility, linearity, and dose rate dependency of the dosimeter were measured for photons of 6 and 15MV and the electrons of 4, 6, 9, 12, and 16MeV. To know the error ranges of the measured data in daily output measurement, the response variations due to geometrical setup errors were measured. As a result of measurement, the error range from the geometrical setup and the reproducibility was less than ${\pm}0.6%$ for given beam qualities in daily output measurement, where the errors from the linearity and the dose rate dependency were negligible. Finally, we concluded that the LinaCheck dosimeter has a good characteristics in terms of dose and setup convenience in daily output measurement. In addition we have shown an examples of clinical use of this dosimeter for measuring daily output more than 60 days.

포스터 발표 제2분과: 야생동물 서식지 특성 및 복원 : 지리산국립공원 방사 반달가슴곰의 형태학적 특성 분석

정동혁,양정진,지형우,이진홍,추연규 한국환경생태학회 2008 한국환경생태학회 학술대회지 Vol.2008 No.1

Orchiectomy in the Asiatic Black Bear (Ursus thibetanus)

정동혁,이승용,양정진,석성훈,공주연,박세진,진소영,김민향,이배근,이희천,연성찬 한국임상수의학회 2015 한국임상수의학회지 Vol.32 No.4

The Asiatic black bear (Ursus thibetanus) is globally protected species and involved in a species restoration program by the Korea National Park Service. However, the bears could not be released into the wild were required regulation of population due to the limited space of breeding facility, so surgical castration was performed in two males. Bears were immobilized with a combination of 2 mg/kg tiletamine-zolazepam and 40 μg/kg medetomidine, and general anesthesia was maintained with isoflurane via endotracheal tube intubation. Orchiectomy was carried out by the closed method using the LigaSure vessel sealing device through pre-scrotal incision. Subcutaneous tissues of the incision site were sutured by continuous pattern with absorbable suture material, and the skin incision was closed with tissue glue. The bears recovered uneventfully from general anesthesia after a duration of 58 min (bear A) and 53 min (bear B). Total surgical time was 26 min (bear A) and 24 min (bear B). No postoperative swelling or complications were observed. This is the first report that describes the use of the LigaSure for orchiectomy in the Asiatic black bear.

강자기장에 의한 깊이선량율(PDD) 변화에 관한 연구 : 10 MV 광자선에 대한 몬테칼로 계산

정동혁,김진기,김정기,신교철,김기환,김성규,김진영,오영기,지영훈 한국의학물리학회 2003 의학물리 Vol.14 No.4

본 연구에서는 몬테칼로 계산을 이용하여 외부 가로 자기장에 의한 깊이선량율(PDD)의 변화를 고찰하였다. 몬테칼로 계산은 자기장에서 전자의 편향을 고려하도록 수정한 EGS4 몬테칼로 코드를 사용하였다. 자기장에서 깊이선량율의 변화를 기술하기 위하여, 선량증가(DI; dose improvement)와 선량감소(DR; dose reduction)를 정의하였다. 10 MV 광자선에 대하여 1-5 T 자기장 범위에서 계산한 결과, 자기장의 세기에 따라 DI와 DR은 거의 선형으로 각각 증가, 감소하였다. 자기장 3 T의 경우에 조사면 10${\times}$10 $\textrm{cm}^2$와 자기장 인가깊이 5-10 cm에서 DI는 1.56 (56% 증가), DR은 0.68 (32% 감소)로 나타났다. 깊이선량율 변화의 원리는 로렌츠 법칙과 전자평형 개념으로부터 설명하였으며, 이러한 특성을 이용하여 방사선치료의 최적화를 달성할 수 있음을 제안하였다. We examined the variation of percent depth dose (PDD) curves for 10 MV X-rays in the presence of magnetic fields. The EGS4 Monte Carlo code was applied and modified to take account of the effect of electron deflection under magnetic field was used. We defined and tested DI (dose improvement) and DR (dose reduction) to describe variation of PDD curves under various magnetic fields. For a magnetic field of 3 T applied at the depth region of 5-10 cm and field size of 10${\times}$10 $\textrm{cm}^2$, the DI is 1.56 (56% improvement) and DR is 0.68 (32% reduction). We explained the results from the Lorentz law and the concept of electron equilibrium. We suggested that the dose optimization in radiotherapy can be achieved from using the characteristics of dose distributions under magnetic fields.

A Subcutaneous Lipoma in a Male Red Fox

정동혁,양정진,공주연,이배근,이제욱,박세진,이승용,석성훈,홍일화,이희천,연성찬 한국임상수의학회 2015 한국임상수의학회지 Vol.32 No.3

An 8-year-old male red fox (Vulpes vulpes) in Species Restoration Technology Institute of Korea National Park Service (KNPS), revealed nodular growths in its ventro-cervical region. The fox was introduced from Young- Yang Gun in 2012 to KNPS for re-introduction of the red fox. It has been cared in captive facility and showed the mass in August 2013 that was sent to Wildlife Medical Center. For the diagnosis of underlying disease and cervical mass, radiographical and sonographical examinations, complete blood count, serum chemistry analysis, peripheral blood smear examination and surgical removal of the mass were performed. The mass was fixed in 10% neutral buffered formalin and processed routinely for haematoxylin and eosin (HE) stain. Based on hematological and serum chemical examination, the fox showed mild leukocytosis, thrombopenia, increase of creatine kinase MB (CKMB) and uric acid. However, it was considered as no clinical relevance since the fox showed no related clinical signs. Macroscopically, the mass was round shape, whitish and well-demarcated. Microscopically, it was diagnosed as a lipoma consisting of mature adipose tissue. Lipoma is a common benign tumor in most domestic animals, however it has never been reported in the red fox. The present case report provides comprehensive diagnosis of a subcutaneous lipoma in a red fox.

선형가속기의 6 MV X-선에 대한 소형 조사면 측정과 몬테 카를로 시뮬레이션

정동혁,이정옥,강정구,김수곤,김승곤,문성록,Jeong Dong Hyeok,Lee Jeong Ok,Kang Jeong Ku,Kim Soo Kon,Kim Seung Kon,Moon Sun Rock 대한방사선종양학회 1998 Radiation Oncology Journal Vol.16 No.2

목적 : 방사선수술의 치료계획에 필요한 기본자료를 얻기 위하여, 6 MV X-선의 소형 조사면을 측정하고, 동일 조사면에 대한 몬테칼로 계산을 수행하여 그 결과를 측정한 자료와 비교하였다. 재료 및 방법 : 연구에 사용한 조사면은 SSD 100 cm에서 직경 1.0, 2.0, 그리고 3.0 cm인 원형의 소형 조사면이며, 각 조사면에 대한 심부선량백분율 (PDD)과 빔측면도 (Beam profile)를 구하였다. 측정에는 소형 반도체검출기, 물팬텀 그리고 원격조정 장치를 이용하였다. 몬테칼로 계산은 EGS4를 이용하여 수행하였으며, 계산에는 6 MV X-선의 에너지 분포와 확산빔 (divergent beam), 원형 조사면 그리고 물팬텀을 고려하였다. 결과 : 심부선량백분율의 경우, 계산값은 측정간에 비하여 낮은 경향을 보였으며, 모든 조사면에 대하여 물팬텀속 깊이 2.0-20.0 cm에서 차이는 0.3-5.7%의 범위로 평가 되었고, 표면 영역에서는 0.0-8.9%로 나타났다. 물팬텀속 깊이 10.0 cm에서 90% 선량폭은 몬테칼로 계산과 잘 일치하였으나, 반음영의 계산값은 모든 조사면에 대하여 측정값보다 0.1 cm 작게 나타났다. 결론 : 측정한 소형 조사면에 대한 심부선량백분율과 빔측면도는 몬테칼로 계산과 근사적으로 일치하였다. 팬텀 표면영역과 반음영 영역에서 측정값과 계산값의 차이가 많이 발생하였으며, 이러한 이유는 몬테칼로 계산 수행시 단순한 기하구조를 가정했기 때문이다. 따라서 실제의 기하구조와 조사면에 대한 보다 정확한 자료를 적용 할 수 있도록, 지속적인 연구를 해야 할 것이며, 몬테칼로 계산은 측정과 검증이 어려운 경우에 대하여 정확한 정보를 얻을 수 있는 유용한 도구로서 많이 이용 될 것이다 Purpose : In order to obtain basic data for treatment plan in radiosurgery, we measured small fields of 6 MV X-rays and compared the measured data with our Monte Carlo simulations for the small fields. Materials and Methods : The small fields of 1.0, 2.0 and 3.0 cm in diameter were used in this study. Percentage depth dose (PDD) and beam Profiles of those fields were measured and calculated. A small semiconductor detector, water phantoms, and a remote control system were used for the measurement Monte Carlo simulations were Performed using the EGS4 code with the input data prepared for the energy distribution of 6 MV X-rays, beam divergence, circular fields and the geometry of the water phantoms. Results : In the case of PDD values, the calculated values were lower than the measured values for all fields and depths, with the differences being 0.3 to 5.7% at the depths of 20 to 20.0 cm and 0.0 to 8.9% at the surface regions. As a result of the analysis of beam profiles for all field sizes at a depth of loom in water phantom, the measured 90% dose widths were in good agreement with the calculated values, however, the calculated Penumbra radii were 0.1 cm shorter than measured values. Conclusion : The measured PDDs and beam profiles agreement with the Monte Carlo calculations approximately. However, it is different when it comes to calculations in the area of phantom surface and penumbra because the Monte Carlo calculations were performed under the simplified geometries. Therefore, we have to study how to include the actual geometries and more precise data for the field area in Monte Carlo calculations. The Monte Carlo calculations will be used as a useful tool for the very complicated conditions in measurement and verification.

스트레칭과 심부강찰마사지 후 스트레칭이 척추신전근 신장성에 미치는 영향

정동혁,두만균 한국스포츠리서치 2002 한국 스포츠 리서치 Vol.13 No.1

황화수소 가스 감지를 위한 고성능 변색성 섬유형 센서의 제작 및 개발

정동혁,맹보희,이준엽,조성빈,안희경,정대웅 한국센서학회 2022 센서학회지 Vol.31 No.3

Hydrogen sulfide(H2S) gas is a high-risk gas that can cause suffocation or death in severe cases, depending on the concentration of exposure. Various studies to detect this gas are still in progress. In this study, we demonstrate a colorimetric sensor that can detect H2S gas using its direct color change. The proposed nanofiber sensor containing a dye material named Lead(II) acetate, which changes its color according to H2S gas reaction, is fabricated by electrospinning. The performance of this sensor is evaluated by measuring RGB changes, ΔE value, and gas selectivity. It has a ΔE value of 5.75×10-3ΔE/s·ppm, showing improved sensitivity up to 1.4 times that of the existing H2S color change detection sensor, which is a result of the large surface area of the nanofibers. The selectivity for H2S gas is confirmed to be an excellent value of almost 70 %.

The Healting Art of Massage and Aromatherapy

정동혁 한국스포츠리서치 2003 한국 스포츠 리서치 Vol.14 No.2

마사지와 아로마테라피의 치료 예술정동혁