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.

화학기상응축공정으로 제조한 Fe(C) 나노캡슐의 합성 및 미세구조

이정한,김성덕,김진천,최철진,이찬규,Lee Jung-Han,Kim Sung-Duk,Kim Jin-Chun,Choi Chul-Jin,Lee Chan-Gyu 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.6

Fe(C) nanocapsules were prepared by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl $(Fe(CO)_5)$. Their characterizations were studied by means of X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The long-chained Fe(C) nanocapsules hav-ing the mean size of under 70 nm could be obtained below $1100^{\circ}C$ in different gas flow rates. The particle size of the powders was increased with increasing decomposition temperature, but it was decreased with increasing CO gas flow rate. The Fe powders produced at $500^{\circ}C$ consisted of three layers of ${\alpha}$-Fe/$Fe_3C$/amorphous phases, but it had two phase core-shell structure which consited of $Fe_3C$ phase of core and graphite of shell at $1100^{\circ}C$.

골격성 III급 부정교합 환자에서 하악골의 이동량과 교합평면의 변화에 따른 술 후 안정성

이정한,김성희,백영재,안경용,황대석,김용덕,김욱규,Lee, Jung-Han,Kim, Sung-Hee,Baek, Young-Jae,Ahn, Kyung-Yong,Hwang, Dae-Seok,Kim, Yong-Deok,Kim, Uk-Kyu 대한악안면성형재건외과학회 2012 Maxillofacial Plastic Reconstructive Surgery Vol.34 No.6

Purpose: The purpose of this study was to evaluate postsurgical facial hard tissue stability after orthognathic surgery with/without posterior impaction in skeletal class III malocclusion patients, and to evaluate the horizontal relapse tendency, according to changes in anteroposterior discrepancy and occlusal planes. Methods: Ninety patients, who had undergone orthognathic surgery in Pusan National University Dental Hospital, were enrolled in this study. Three main groups were classified as follows: Thirty patients underwent mandibular setback bilateral sagittal split ramus osteotomy (BSSRO) only (BSSRO group, BG); another thirty patients underwent mandibular setback BSSRO and Le Fort I osteotomy with posterior impaction (posterior impaction group, PG); and another thirty patients underwent mandibular setback BSSRO and Le Fort I osteotomy without posterior impaction (non-posterior impaction group, NPG). Preoperative (T0), immediate postoperative (T1) and six-month follow-up period (T2) lateral cephalograms were taken, and various parameters were measured. The analyses were done by linear and angular measurements between T0-T1 and T1-T2, to evaluate postsurgical facial hard tissue stability. Results: Mean horizontal relapse rates were distributed from 11.81% to 19.08%, and there were significant postsurgical changes (0.52 mm~2.44 mm) at the B point in all 3 groups. But, there were no statistical differences on relapse rate among BG, PG and NPG patients. Conclusion: In this study, the postsurgical stabilities of BSSRO and Le Fort I osteotomy with/without posterior impaction in skeletal class III malocclusion patients were acceptable. There were no significant statistical differences in mandibular stability according to changes in anteroposterior discrepancy and occlusal planes.

학교시설 지진피해 현황과 대책

이정한,Lee, Jung-Han 한국교육시설학회 2011 교육시설 Vol.18 No.3

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.

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.

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.

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.

이동식 정자의 설계 시공법 연구

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

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.

『임원경제지』 「섬용지」와 문화재수리 표준시방서를 통해 본 전통조경공간 설계 시공방법

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

The purpose of this study is to examine the design & construction methods of the traditional landscape space of the past and the repair and maintenance of cultural heritages to maintain it today. To this end, the method of narrative description, process extraction and construction related to traditional landscaping were compared to each other based on the 『Imwongyeongjeji』 「Seomyongji」 and 'Standard Specification for Repairing Cultural Heritages'. The results are as follows; First, to analyze at the description methods of the 『Imwongyeongjeji』 「Seomyongji」 and 'Standard Specification for Repairing Cultural Heritages' and related processes in the field of traditional landscaping. 『Imwongyeongjeji』 「Seomyongji」 was an encyclopedia of the overall construction method of the living space, describing the location, effect, and advantages and disadvantages of each component and presenting quantitative figures to institutionalize the construction of traditional landscaping spaces. 'Standard Specification for Repairing Cultural Heritages' presented the entire process of repairing cultural heritages, and it is becoming a kind of guide for reference at the site. Among them, foundation construction, roof construction, landscape construction, and fence construction were drawn as items that could be applied to traditional landscaping areas. Second, the traditional landscape space construction method was divided into the processes of foundation construction, roof construction, landscaping construction, and fence construction. Foundation construction is a way of repeating the process of land-tramping. During the construction of the roof, the tile-roofed building was built on top of the rafters and roofed with tiles. And thatched roof was made to a number of rice straws bundles to cover the roof one after the other. Instead of tiles, the stone roof was made of thin and wide stones, and the wooden boards were used for the single roof and the bark roof were constructed with many layers of dried corrugations. Landscape construction mainly consists of the Paving technique through tramping rubble and the construction of terraced flower by planting stone, plants, and shrubs on the top. According to the building materials, the wall construction was derived from the earth-stacked earthen wall, stone walls using stone and clay, marble walls made of tile patterns, and the construction of a board wall using a wood board as a wall. Third, comparing the construction methods of the 『Imwongyeongjeji』 「Seomyongji」 and 'Standard Specification for Repairing Cultural Heritages', 『Imwongyeongjeji』 「Seomyongji」 focuses on standardizing the construction methods to create a new traditional space. There is a difference in the setting of the scope of the 『Imwongyeongjeji』 「Seomyongji」 and the construction because 'Standard Specification for Repairing Cultural Heritages' provides the overall construction procedure considering the diversity of the cultural heritages. In addition, the traditional landscape space used to be a residential space in the past, but today, the maintenance process of the already established facilities as designated cultural heritages has been carried out, and construction methods have been added to create viewing conditions. In terms of the succession of traditional knowledge, some similar methods were found in the repair of cultural assets today, and some cases were also confirmed in the reconstruction of traditional technologies such as application of some materials or mix, separation of added facilities and introduction of efficient construction methods.