탄소 나노튜브의 전계방출 특성

이경원,김은미,권민철,김용,이재열,박홍준 동아대학교 기초과학연구소 2000 基礎科學硏究論文集 Vol.17 No.1

본 연구에서는 emitter와 collector 사이의 간격과 current density 대 electric field (J-K)특성을 초점으로 카본나노튜브의 전계방출 특성을 조사하였다. 카본 소스로 CH4, 촉매 및 희석가스로서 NH3를 사용하고 HFCVD를 이용하여 실리콘 위에 카본나노튜브를 성장하였다. 나노튜브의 지름이 20-40nm이고 길이는 15㎛이다. I-V곡선에서 onset voltage는 Vons=3.36V/㎛이고, 2.5V/㎛ 의 전기장에서 8mA/cm2이상의 높은 전류밀도 특성을 보였다. Fowler-Nordheim 그래프를 그려서 팁의 특성을 나타내는 β값을 계산하였다. We report the field emission properties of carbon nanotube, focusing on current density versus electric field (J-F) characteristics and the spacing between the emitter and collector. We grow carbon nanotubes on sillicon using hot-fillament chemical vapor deposition, using CH4 gas as the carbon source and NH3 gas as the catalyst and dilution gas. Nanotubes are distributed from 20 to 40nm in diameter and 15㎛ long. Onset field of the field emission is 3.36V/㎛ and the current density is 8mA/cm2 at an electric field of 2.5V/㎛. A Fowler-Nordheim plot was made. Field enhancement factor β is calculated.

八段錦의 원리와 수련에 대한 연구

이용태,김경철 동의대학교 한의학연구소 1997 동의한의연구 Vol.1 No.-

The principle and training of PAL DAN PUM is studied and the results is as follows : 1. PAL DAN GUM is the method to be belonged the course of "TONG GI" for the base of GI GONG training. 2. As the body is extended and for a short time the breath is stopped, Meridian is stimulated by PAL DAN GUM. 3. PAL DAN GUM have to be acted in the condition of the whole unity of the heart, the breath and the body.

응급의료센터 과밀화 해소를 위한 환자 전원

이경룡,구홍두,박인철,김승환,장석준,심호식 대한응급의학회 1995 대한응급의학회지 Vol.6 No.2

To reduce the degree of overcrowding in level Ⅲ emergency care centers, authors have conducted a prospective study of patient who were transferred to level Ⅰ or Ⅲemergency center based on the non-emergent patient guideline currently used at the severance Hospital, level Ⅲ emergency center, during the period of 65 days from Jan. 1st 1995 to Mar. 6th 1995. Followings are guideline for non-emergent patient described by the Korean government low: 1) systolic blood pressure greater than 80/100 of normal. 2) respiration rate between 10 to 24 per minute. 3) pulse rate between 60 to 100 per minute. 4) body temperature between 36 to 37.5℃ by rectal. 5) relatively alert mental status. 6) patient not requiring emergency operation at the time of examination. The results were as follows: 1. Among the total 5,301 patients, 464 patients ranged from age of 1 to 82 years old were transferred to level Ⅰor Ⅱ emergency center after simple treatment. 2. Among the 464 patients, 276 patients were treated in expected hospital with medical problems in 101 (36.6%) patients, and 175 (63.4%) patients had surgical problems. 3. Among the 276 patients, 122 (44.2%) patients were admitted, 145 (52.9%) patients were discharged from the emergency room after adequate treatment. 4. Among the transferred patients, simple laceration (33.0%) were most common, acute gastroenteritis (12.0%), and simple contusion (10.5%) were followed. These results suggest that about 10% of patients visiting level Ⅲ emergency care center, can be safely transferred to nearest level Ⅰor Ⅱ emergency centers on the bases of non-emergent patient guideline described by Emergency Medical Service law. These guideline, if put into proper use, can reduce the degree of overcrowding problems in level Ⅲ emergency care center through out the country.

구급차를 이용한 응급 환자의 중증도 분류

박인철,이경룡,이한식 大韓應急醫學會 1996 대한응급의학회지 Vol.7 No.1

Authors performed a prospective study of patients who visited to ED of Severance Hospital via ambulance during the period of six months from April, 1, 1995 to September, 30, 1995. Our study assessed the adequate patient transfer via EMS system and to suggest more advanced guideline for patient transfer. The results were as follows: 1) Among the total 16,794 patients, 2,250 visited via ambulance ranged from age of 1 to 89 years old with an average 43yrs. 2) Among 2,250 patients, 1,122(50%) visited via 119 system, 546(24%) via 129 EMS system, and 582(26%) via other hospital ambulances 3) 270(12%) patients were classified into urgent, 894(405) into emergent, and 1,086(48.4%) into non-emergent. 4) For the patients via 119 system, 102(9.1%) patients were classified urgent and 630(56.1%) non-emergent, via 129 EMS system, 78(14.3%) urgent and 228(41.8%) non-emergent, and via other hospital ambulances, 90(15.5%) urgent and 228(39.2%) non-emergent. These results show that patients who visited level Ⅲ emergency care center via ambulances were classified into non-emergent about 50%. We conclude that if more effective classifying system which used by EMT for emergency patients is applyed, non-emergent patients can be transferred to more low grade emergency center, and the overcrowding of level Ⅲ emergency center can be improved.

流體로 채워진 圓筒 Channel內 捧 集合體의 振動解析

鄭炅勳,李聖哲 全北大學校 1993 論文集 Vol.36 No.-

Free vibration of the tube bundle in a channel filled with stationary liquid is investigated. Added mass coefficients which are based on velocity potential theory are calculated and used to computing the natural frequencies and mode shapes of tube bundle in liquid. The natural frequencies of the tube bundle are obtained as a function of the spacing between tubes and verified by an experiment. The experimental results show good agreement with the computer predictions. As the spacing between the tubes is small, namely gap to diameter(G/D) becomes small, coupled natural frequencies are widely distributed. A wide spacing tube bundle goes the results of single tube in an infinite liquid.

칼슘제 수관살포가 참다래의 과실 품질과 저장에 미치는 영향

임경호,나양기,임동근,마경철,조윤섭,김월수,이상현,박용서 全南大學校 農業科學技術硏究所 2001 農業科學技術硏究 Vol.36 No.-

This study were carried out to improve Kiwifruit quality and storage life. Three kinds of calcium compound were sprayed and calcium content of fruits, weight loss during fruit storage and fruit quality were investigated. Calcium contents within leaves and fruit were lower in Clef-non treatment than that of control. The calcium content in fruit pericarp of Kalk-H and CaCl2 was 0.04 to 0.05% higher than that of control. Fruit weight and soluble solids content at harvest was a little higher but acidity and fruit hardness was lowered. Fruit weight loss of Kalk-H and CaCl2 treatment was 1.39 to 1.53% lower than that of control during storage. The soluble solids of ripen fruit was 1.0 to 1.3% higher in all treatment and 0.8% higher in Kalk-H treatment in 120 of after storage. Fruit hardness of control fruit was higher at harvest but that of CaCl2 treatmented fruit was 0.39㎏/φ 5㎜ higher in 120 days of storage.

광에너지 총량에 따른 광중합 콤포짓트레진과 콤포머의 중합도에 관한 연구

황경란,이용근,임범순,김철위 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4

Dental composite resin is filler added, particle reinforced composite material, and the usage range had been enlarged in the posterior restoration through improvement of physical properties. Recently, resin modified glassionomer and compomer are used for various purposes. The degree of polymerization of cross-liked polymer has great importance in determining the mechanical properties and clinical availability of materials. Residual carbon-carbon double bonds have been implicated in causing reduced wear resistance, strength and color stability. The degree of polymerization is an important factor for longevity of a restoration. However the higher the degree of polymerization in resin composites, the higher the shrinkage will result. It has been elucidated that the degree of polymerization was significantly affected by the intensity of the curing light, wavelength of light and irradiation time. In this experiment, 16 kinds of restorative materials such as five kinds of universal composite resin, five kinds of condensable composite resin, two kinds of flowable composite resin, and four kinds of compomer were used. This study examined the effect of light intensity and irradiation time on the polymerization behavior such as the heat release during polymerization and the rate of polymerization by DSC (differential scanning calorimeter), and the degree of double bond conversion by FT-IR. With DSC, the irradiation modes were three different light intensity of 300, 400, 600 ㎽/㎠ and for 40 seconds. With FT-IR, the levels of irradiation energy were 1,500, 40,000, 8,000, 16,000 and 24,000 mJ/㎠ by combining the light intensity of 300, 400, 600 ㎽/㎠ and irradiation time of 5, 10, 20 and 40 seconds. From this experiment, The following results were obtained : 1.In the DSC result, heat of polymerization of composite resin was 23.22∼55.17J/gram and exothermic energy of compomer was 26.50∼52.68 J/gram 2.At the isothermal condition of 27℃, there were exothermal peaks at 40.812∼44.724 seconds from the start of irradiation. The percentage of polymerization by released heat was 19.12∼49.44% after 18 seconds, 37.23∼82.07% after 36 seconds, and 93.57∼98.53% after 54 seconds from the start of irradiation. 3.From FT-IR, the degree of polymerization of composite resin was 17.17∼60.91% and that of compomer was 7.74∼40.82%, and the degree of final conversion was influenced by the kinds of restorative materials and the irradiation energy(p<0.01). 4.As the irradiation energy was increased from 1,500 mJ/㎠ to 16,000 mJ/㎠, the degree of conversion was increased also. However, the degree of final conversion was no significant differences with the irradiation energy of 24,000 mJ/㎠ and 16,000 mJ/㎠(p>0.05). The wavenumber of absorbance peak of aromatic double bond was similar regardless of the restorative materials, and appeared around 1606.67∼1610.67 cm-1. The absorbance peak of aliphatic double bond appeared around 1636.64∼1638.52 cm-1 from FT-IR.

병원 도착 전 사망 환자의 사인기재에 관한 고찰

강용선,이경룡,박인철,조광현,김승호,이한식 대한응급의학회 2001 대한응급의학회지 Vol.12 No.4

Background: To the emergency physician, issuing a death certificate is becoming a burden as the DOAs(Deaths on Arrival) have increased in recent years. We analyzed the agreement on the causes of death issued by emergency physicians and attempted to find out whether emergency physicians complied with the guidelines for issuing death certificates. Material & Method: A survey questionnaire containing twelve pre-selected DOA cases which were supplemented with relevant past medical history and physical examination was used. The cases, with varying causes of death, were chosen from the medical records of DOA patients who presented to the emergency department at Severance Hospital, Yonsei University College of Medicine, from January 1997 to December 2000. The questionnaires were sent to 60 emergency physicians(22 specialists and 38 residents) at 22 university-affiliated teaching hospitals and 2 general hospitals across the nation. They were asked to identify the most probable direct cause of death for each of the 12 cases. The same questionnaire was sent to medical examiners at the National Institute of Scientific Investigation and to a Korean emergency physician at Albert Einstein College of Medicine in New York, USA. We also included an open question about the optimal age for the use of 'senility' as a cause of death. Results: All 60 emergency physicians responded to the survey. The average number of causes of death per case was 9.7(7∼ 14). The range of concordance of causes of death was 23.3% to 66.6%. Out of a total of 720 causes of death given by the emergency physicians,35(4.9%) failed to adhere to the death certification guidelines, Also, 210 causes of death were not listed in the Korean classification of standard causes of death. Interestingly, the medical examiner answered 'unknown etiology' and the emergency physician in the USA answered 'cardiopulmonary arrest' or 'respiratory arrest' in most cases. Regarding 'senility' as a cause of death, 22 physicians(36.7%) thought the optimal age was over 80 years. Conclusion: A significant lack of agreement exists in determining the cause of death for the DOA patients arriving at emergency departments, Therefore, an all-out effort is essential to find ways to improve and resolve this situation. As the death certificate is a legal document and a basis for vital statistics, emergency physician should seek a rational consensus to improve and resolve these inconsistencies.

유체로 연성된 동일한 두 직사각 평판의 고유진동 해석

유계형,정경훈,이성철 한국산업안전학회 2002 한국안전학회지 Vol.17 No.2

In order to investigate the vibration characteristics of fluid-structure interaction problem, we modeled two identical rectangular plates coupled with fluid. A commercial computer code, ANSYS was used to perform finite element analysis and FEM solutions were compared with the experimental results to verify the finite element model. As a result, comparison of FEM and experiment showed good agreement, and the transverse vibration modes, in-phase and out-of-phase, were observed alternately in the fluid-coupled system. The effect of fluid gap size on the fluid-coupled natural frequency were investigated. It was shown that the mode numbers increased, the normalized natural frequencies monotonically increased. And it was also found that an increase of the fluid gap reduced the coupled natural frequencies for the in-phase modes but increased the coupled natural frequencies for the out-of-phase modes, and eventually converged to the results of an infinite fluid gap.

비가림 및 망사 시설재배가 참다래의 수체생육 및 과실품질에 미치는 영향

나양기,마경철,임동근,김병삼,임경호,김월수,이상현,박용서 全南大學校 農業科學技術硏究所 2001 農業科學技術硏究 Vol.36 No.-

This studies were conducted to investigate the effects of rain shelter and netting on the tree growth, fruit set fruit quality of kiwifruit (Actinidia deliciosa). In rain shelter and net house, shoot falling wasn't occurred by strong wind, and fruit set, fruit weight and also fruit malformation, side flowering increased at the same time. In rain shelter house the increment temperature forced blooming date and increased shoot length, leaf number and diameter but in net house these tendencies were not observed. Relative light intensity of rain shelter house was higher than that of net house with standard of field culture (relative light intensity: 100%). Soluble solid content was higher in rain shelter house, and acid content was higher in net house. With the effect of rain sheltering the occurrence of bacterial bloom rot and canker significantly decreased in both rain shelter and net house but insect injury increased. These data showed that rain shelter house is more suitable for kiwi fruit culture.