유한요소법에 의한 자기공명영상시스템에서의 와전류 영향 분석

이정한,강현수,조민형,문치웅,이강석,이수열,Lee, Jeong-Han,Gang, Hyeon-Su,Jo, Min-Hyeong,Mun, Chi-Ung,Lee, Gang-Seok,Lee, Su-Yeol 대한의용생체공학회 1999 의공학회지 Vol.20 No.1

Eddy current in MRI systems degrades gradient field linearity and distorts gradient waveform. When the waveform distortion is spatially variant, it is very difficult to perform special imaging techniques such as the echo planar imaging technique or the fast spin echo imaging technique. In this study, we have developed a new technique to estimate the distorted gradient waveforms at any points inside the imaging region using the finite element method. After obtaining the eddy-current-effect transfer function, which represents magnitude and phase characteristics of the gradient field at a particular point, we have used the transfer function to estimate the actual gradient waveforms at the point. To verify the proposed technique, we have compared the estimated gradient waveforms with the measured ones. 자기공명영상시스템에서 경사자계코일에 전류 펄스를 인가할 때 코일 주변의 도전성 구조물에 유도되는 와전류는 경사자계의 선형성을 열화 시킬 뿐만 아니라 경사자계의 파형을 왜곡시킨다. 특히 경사자계 파형의 왜곡 정도가 공간 위치에 따라 다를 경우 고속촬영법과 같은 고성능의 자기공명영상법을 실현하는 것이 어려워 진다. 본 연구에서는 촬영 공간 내 임의의 지점에서 와전류에 의해 경사자계 파형이 변형되는 정도를 알 수 있는 방법을 유한요소법을 이용해 구하였다. 경사자계코일에 정현파를 인가했을 때 임의의 지점에서 자계의 진폭 및 위상 특성이 주파수에 따라 어떻게 변하는지를 나타내는 와전류 영향 전달함수를 구하였고, 이 전달함수를 이용해 임의의 입력 전류 파형에 대한 출력 경사자계 파형을 예측하였다. 제안한 방법의 타당성을 검증하기 위해 실제로 측정한 경사자계 파형을 예측한 파형과 비교하여 제시하였다.

의료영상의 화질

이정한,Lee, Jeong-Han 대한디지털의료영상학회 1998 대한디지털의료영상학회논문지 Vol.4 No.1

사회복지시설에 종사하는 일부 재활전문가들의 방문재활에 대한 필요성 조사

이정한,김계엽,김은정,Lee, Jeong-Han,Kim, Gye-Yeop,Kim, Eun-Jung 대한물리치료학회 2010 대한물리치료학회지 Vol.22 No.5

Purpose: The purpose of this study was to analyze the necessity of home visit rehabilitation therapy by rehabilitation professionals working at social welfare facilities. Methods: The subjects of this study were 227 rehabilitation professionals (social worker, nurse, physical therapist, occupational therapist, speech-language therapist, special education teacher, and staff of institutions for the disabled who were working at community rehabilitation centers. The data were collected over 65 days (2008. 09. 10~11. 14). The results were analysed statistically by the Chi-square test. Results: The results are as follows: Long-term care service was established in Korea by the Ministry of Health in July, 2008. But there are limits to their being able to provide various rehabilitation services for chronic patients and old people. According to a recent survey, almost all rehabilitation professionals (N=227) stated that home visit rehabilitation therapy is necessary. Conclusion: In Korea, the long-term care service has a nursing service and a service supporting physical activities of daily living, but not physical therapy. So, home visit rehabilitation services should include physical therapy, rehabilitation exercise, and pain management.

이동식 정자의 설계 시공법 연구

이정한,Lee, Jung-Han 한국전통조경학회 2019 한국전통조경학회지 Vol.37 No.4

본 연구는 이동식 정자의 설계시공방법을 살펴보고자 문헌분석을 통해 조영 배경과 입지와 향의 설정, 규모와 구성, 재료, 시공방법 등을 분석함으로써 다음과 같은 결과를 도출하였다. 첫째, 이동식 정자는 곳곳에 펼쳐진 경승을 두루 유람하기 위해 고안된 정자로 산수를 즐기는 경험을 바탕으로 자신의 집을 소유하고 정자를 경영하는 것보다 이상적인 삶을 추구하는 방식이 반영된 창작물이었다. 둘째, 이동식 정자의 조영은 계절별, 시기별 경관을 때와 장소의 제한 없이 감상하고자 하는 의도로 조성되었으며. 풍류를 즐기기 위한 도구를 매번 옮겨야 하는 번거로움을 해소하고자 고안되었다. 셋째, 이동식 정자는 경관을 조망하기 용이한 곳을 향하여 입지와 향이 결정되며, 대부분 소규모로 조성되어 그 안에서 경관을 감상하거나, 바둑, 작시, 탄금 등을 위한 공간을 구분하였다. 또한 목재를 주로 사용하고, 하중을 저감시키기 위해 대나무나 짚, 유둔, 면포 등 가벼운 소재로 지붕과 벽면을 구성하였다. 시공방식은 결합과 해체가 용이하도록 하는 결구기법이 주로 사용되었으며, 선박이나 수레 상부에 정자를 조성할 경우에는 일반 정자의 목구조식 시공이 이루어졌다. 넷째, 일반 정자와 이동식 정자의 설계시공 특성을 비교해보면 이동식 정자는 조영목적상 경관의 관람이 용이하여 입지와 향의 설정에 제한이 없으나, 기동력을 고려하고, 구조적으로 하중을 견디기 위한 방안이 마련되어야 하며, 정자로서의 기능과 형태를 만족시켜야 하기 때문에 보다 엄격한 제도와 기법이 요구되었다. This study aims to examine the design and construction methods of movable Pavilions. Through the literature analysis, the setting up of the construction background, location and direction, size and composition, materials and construction methods were analyzed. The results are as follows; First, the movable pavilion is designed to enjoy a wide range of views. It was a creation that reflected the way in which the ideal life was pursued based on the experience of enjoying scenery rather than owning one's own house and running a pavilion. Second, the formation of movable pavilion was intended to enjoy the scenery by season without restrictions on time and place. It can also relieve the hassle of having to move tools to enjoy the wind every time. Third, the movable pavilion faces to a place with good scenery and determines its position and direction. Most of them were built on a small scale and divided the space for viewing the scenery, playing GO(Baduk), writing poems, and playing musical instruments. Also, wood was used mainly. To reduce the load, roofs and walls were constructed with light materials such as bamboo, straw, thick sheet of oil, and cotton cloth. The construction method was mainly used by the method of fastening for easy coupling and dismantling. When a building was constructed on the upper part of a ship or cart, the wooden structure of a regular pavilion was constructed. Fourth, when comparing the design and construction characteristics of ordinary pavilion and movable pavilion, the movable pavilion is easy to see for contrast purposes, so there is no limit to setting the location and direction. Instead, more stringent systems and techniques were called for, because as mobility forces should be considered, structurally measures to withstand loads, and they should satisfy their function and form as pavilion.

경추부 후종인대 골화증 1례에 대한 증례보고

이정한,박태용,조준기,김대중,김남수,신병철,송용선,고연석,Lee, Jeong-Han,Park, Tae-Yong,Jo, Joon-Ki,Kim, Dae-Joong,Kim, Nam-Su,Shin, Byung-Cheul,Song, Yung-Sun,Ko, Youn-Seok 척추신경추나의학회 2005 대한추나의학회지 Vol.6 No.1

Objective : There is hardly case report in oriental Medicine about the ossification of the posterior longitudinal ligament(OPLL). We experienced a patient(64-year-old male) with OPLL improved by oriental Medicine treatment, and we report it clinically. Methods : While the patient with OPLL was treated acupuncture, physical therapy, and CHUNA manual therapy, we evaluated the patient's symptoms and function by visual analogue scale(VAS), clinical criteria for evaluation of the cervical myelopathy by the japanese orthopaedic association(JOA Score) and cervical spine's range of motion(ROM) in three limes for the 17 days that were a hospitalization period. Results : VAS, JOA score and ROM in OPLL patient were improved. VAS in symptoms became lower from 10 to 5. JOA score increased from 12 points to 13 points. As for the ROM, it was improved in 30.1%. Conclusion : Oriental medicine treatment may be effective in conservative treatment of OPLL. We propose that more clinical studies and reaches are accomplished in oriental medicine.

여름잎마름병(Summer patch) 병원균에 대한 살균제의 억제효과 조사

이정한,심규열,김정호,전창욱,곽연식,Lee, Jung Han,Shim, Gyu Yul,Kim, Jeong Ho,Jeon, Chang Wook,Kwak, Youn-Sig 한국잡초학회 한국잔디학회 2017 Weed & Turfgrass Science Vol.6 No.2

국내 Kentucky bluegrass로 조성된 골프장이나 잔디 재배지에서 여름철에 여름잎마름병 발생으로 인한 피해가 심각한 상황이다. 그럼에도 불구하고 여름잎마름병방제약제가 아직까지 등록되어있지 않아 병원균에 효과적인 약제를 선발하기 위하여 본 연구를 수행하였다. 전형적인 여름잎마름병 병징에서 병원균을 분리하였고 ITS1과 ITS4 염기서열 분석으로 Magnaporthiopsis poae로 동정되었다. 잔디용으로 사용되는 10개의 약제를 대상으로 병원균 반응을 조사한 결과, 약제의 농도가 높아질수록 병원균 생장을 억제하였고 시간이 경과할수록 병원균 억제효과가 떨어지는 것이 관찰되었다. triazole계 약제 4종(metconazole, myclobutanil, propiconazole과 tebuconazole)의 병원균 억제효과는 100%로 나타났다. 다음으로 thiophanate-methyl의 억제효과가 높았으며 strobilurin계의 약제인 azoxystrobin, pyraclostrobin과 trifloxystrobin 약제를 비교하였을 때는 pyraclostrobin 약제가 가장 높게 나타났으며 다음으로 azoxystrobin과 trifloxystrobin 순으로 나타났다. Fludioxonil과 fluxapyroxad의 병원균 억제효과는 trifloxystrobin과 유사하게 나타났다. Summer patch is the most serious disease at turfgrass field or golf course established with Kentucky bluegrass during high temperature season in Korea. Nevertheless, chemicals for the summer patch control are not yet registered in Korea. We isolated the pathogens from the turfgrass showing typical summer patch symptoms and identified as Magnaporthiopsis poae by using the internal transcribed spacer ITS1 and ITS4 sequences of rDNA. The inhibition rates of the pathogen were investigated for 10 fungicides. As results, the pathogen growth was suppressed when chemicals concentration increased and negatively correlated with incubation period with the chemicals. In triazole group, all chemicals (metconazole, myclobutanil, propiconazole and tebuconazole) treated showed the inhibition rates by 100%. Thiophanate-methyl showed the next highest inhibition effect against a summer patch pathogen. In strobilurin group, pyraclostrobin was the highest suppression effect compared with azoxystrobin and trifloxystrobin. Inhibition effect of fludioxonil and fluxapyroxad on pathogen was similar to the trifloxystrobin. Based on the results, triazole and carboxamide groups are strongly recommended due to the highest inhibition effect on the summer patch pathogen, Magnaporthiopsis poae.

국내 골프코스의 켄터키블루그래스에 Laetisaria fuciformis에 의한 붉은뿔마름병(Red Thread) 발생보고

이정한,김정호,심규열,곽연식,Lee, Jung Han,Kim, Jeong Ho,Shim, Gyu Yul,Kwak, Youn-Sig 한국잡초학회 한국잔디학회 2018 Weed & Turfgrass Science Vol.7 No.3

2017년 4월 중순 경남 양산에 소재한 골프장에서 Laetisariafuciformis에 의한 redthread 병징이 켄터키블루그래스에 발생하였다. 골프코스의 페어웨이에 불규칙한 모양의 병반 형태로 발생하였다. 감염된 잎은 마름증상을 보이면서 점차 볏짚색으로 변했으며, 잎의 끝부분은 실모양으로 헝클어져있었다. 이른 아침에는 분홍빛을 띤 젤라틴 형태로된 사슴뿔 모양의 균핵을 형성하였다. 배양적 특징으로 균총은 옅은 분홍색이었으며 균사다발이 형성되었고 3-5mm 크기의 연한 분홍색 균핵을 형성하였다. 병원균은 형태, 배양적특징 및 분자생물학적 특징을 토대로 L. fuciformis로 동정되었다. 코흐의 원칙에 따라 병원성 검정을 실시하여 켄터키블루그래스에 병원성이 있음을 확인하였다. 이는 한국에서 L. fuciformis에 의해 켄터키블루그래스에 발생하는 redthread에 대한 최초의 보고이다. In the middle of May 2018, typical red thread disease symptoms were observed on Kentucky bluegrass (Poa pratensis L.) on a golf course, which locates at Yangsan, Gyeongnam province in Korea. Irregular-shaped patched symptoms were observed in fairway of golf course. The foliar symptom was dried out and faded to straw color and tip of the grass leaves were tangled like thread. Early morning, infected and tangled leaves were covered with the pinkish gelatinous antler-like structure (sclerotinia) as a typical red thread disease symptom. Causal fungal pathogens were isolated from the symptom in Kentucky bluegrass. The fungal culture characteristic on potato dextrose agar color of colony was pale pink and conjugated hyphae, sclerotium of irregular shape was pale pink and 3~5mm diameter in size. The pathogen was identified as Laetisaria fuciformis based on morphological and culture characteristics as well as molecular characteristics. Pathogenicity test was verified on the Kentucky bluegrass by Koch's postulates. This is the first report of red thread disease occurrence in Kentucky bluegrass by L. fuciformis in Korea.

산업장 근로자의 주관적 건강인식에 영향을 미치는 요인 분석

이정한,고연석,권소희,김삼태,정해경,박승정,송용선,이기남,Lee Jeong-Han,Ko Youn-Seok,Kwon So-Hee,Kim Sam-Tae,Jung Hae-Kyoung,Park Seung-Jong,Song Yung-Sun,Lee Ki-Nam 대한예방한의학회 2004 대한예방한의학회지 Vol.8 No.1

This study tried to analyze influencing factors on self-perceived health status(SPHS) of labors in workplace. and suggested the preventive oriental medicine approaches in occupational health care. 914 data for research were collected through the process of oriental health examination with questionnaire in workplace and collected data were analyzed with frequency, homogeneity and correlation statistically. The results were as follows : 1) The distributions of SPHS was 58.4% of healthy group. 41.6% of unhealthy group. 2) For the difference of SPHS by stress, the high level stress group was more included in healthy group(p<0.05). 3. For the difference of SPHS by health behavior. the higher score of health behavior group was more included in healthy group. There was statistically significant difference of SPHS in physical exercise, but not in smoking, drinking, sleeping and body mass index. 4. For the difference of SPHS by the latest health examination results, non-disease group was more included in healthy group, while disease group was more included in unhealthy group. From the above results, SPHS was influenced by stress, health behavior, the latest health examination results. Therefore oriental medical service for occupational health must be interested in the these influencing factors and make an effort to change their perception of health as well as physical improvement.

레이저 열원을 이용한 마그네슘 합금의 용접성에 관한 연구 (I) - AZ31B-H24 및 AZ31B-O의 레이저 용접성 비교 -

이정한,김종도,이문용,Lee, Jung-Han,Kim, Jong-Do,Lee, Mun-Yong 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.5

This study is related to the laser weldability of AZ31B magnesium alloy, an all-purpose wrought alloy with good strength and ductility. In general, AZ31B is classified into AZ31B-H24 and AZ31B-O depending on temper designation. Thus, in this study, the laser weldability of AZ31B-H24 and AZ31B-O was investigated and compared. CW Nd:YAG laser was used to produce bead and butt joints. And the effects of welding conditions on the weldability of these joints were examined in detail. As a result of this study, AZ31B-H24 was found to have thinner oxide film and smaller grain size compared with AZ31B-O. Due to such difference, in bead welding, AZ31B-H24 had more wide welding range for full penetration compared with AZ31B-O. Furthermore, it was also confirmed that AZ31B-H24 and AZ31B-O have different welding conditions to obtain stable keyhole in butt welding.

레이저 열원을 이용한 마그네슘 합금의 용접성에 관한 연구 (II) - AZ31B-H24 및 AZ31B-O 레이저 용접부의 기계적 특성 -

이정한,김종도,이문용,Lee, Jung-Han,Kim, Jong-Do,Lee, Mun-Yong 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.6

Magnesium alloy sheet which is commercially available in the market presently is AZ31B, a Mg-Al-Zn three elements alloy. AZ31B is used by being classified into AZ31B-H24 and AZ31B-O depending on temper designation. In this study, AZ31B-H24 and AZ31B-O alloy sheets with 1.25mm thickness were butt-welded using CW Nd:YAG laser. And the effect of materials on mechanical properties was investigated by tensile and hardness tests. As a result of this study, regardless of materials, the butt-welded joint did not show a significant difference in tensile strength and hardness values. However, compared with the basemetal, the AZ31B-O showed more outstanding mechanical properties than AZ31B-H24, and that is because H24 material lost the effect of work hardening during welding.