구리를 함유하지 않은 친환경 자동차 브레이크 패드의 마모 특성에 관한 연구

김기봉,양상선,이성주,황석훈,김신욱,김용진,Kim, Ki-Bong,Yang, Sangsun,Lee, Seong-Ju,Hwang, Suk-Hun,Kim, Sin-Wook,Kim, Yong-Jin 한국분말야금학회 2018 한국분말재료학회지 (KPMI) Vol.25 No.1

The friction characteristics of Al-Fe alloy powders are investigated in order to develop an eco-friendly friction material to replace Cu fiber, a constituent of brake-pad friction materials. Irregularly shaped Al-Fe alloy powders, prepared by gas atomization, are more uniformly dispersed than conventional Cu fiber on the brake pad matrix. The wear rate of the friction material using Al-8Fe alloy powder is lower than that of the Cu fiber material. The change in friction coefficient according to the friction lap times is 7.2% for the Cu fiber, but within 3.8% for the Al-Fe alloy material, which also shows excellent judder characteristics. The Al-Fe alloy powders are uniformly distributed in the brake pad matrix and oxide films of Al and Fe are homogeneously formed at the friction interface between the disc and pad, thus exhibiting excellent friction and lubrication characteristics. The brake pad containing Al-Fe powders avoids contamination by Cu dust, which is generated during braking, by replacing the Cu fiber while maintaining the friction and lubrication performance.

소아(小兒) 임상상(臨床上) 한약제형(韓藥劑形)에 관(關)한 연구(硏究)

김기봉,김장현,Kim Ki-Bong,Kim Jang-Hyun 대한한방소아과학회 1999 대한한방소아과학회지 Vol.13 No.2

In children, flesh and muscle are tender, mental function is feeble, digestion and absorption are weak. Also food, drink and medicine which burden the stomach and bowels must be avoided. Oriental medicines are divided in object of medical treatment into three types, liquid medicine, medicinal powder and pill. In spite of this types, time and effort are spended greatly on children's eating medicine. In this paper, studying general characteristic of oriental medicinal types and effective types of oriental medicine, I can obstain such conclusions. 1. The oriental iense pillow remedy sets at easy, promotes degistion, treats disease of theesporatory organs. 2. The distillation remedy is suited to a chronic disease of children the degistion are ak in. 3. The mother remedy, because medicine is supplied through mother's body, is effective to infant. 4. The external use remedy is suited to skin disease, eye disease and nose disease, and has similar effect to taking liquid medicine. 5. The confectionery remedy is the method which children like greatly, but is the effective method to many children because of technical manufacture.

소아(小兒) stress에 관한 문헌적(文獻的) 고찰(考察)

김기봉,김장현,Kim, Ki-Bong,Kim, Jang-Hyun 대한한방소아과학회 2002 대한한방소아과학회지 Vol.16 No.1

With the progress of civilization, the disorders due to the stress, which derived from the social-structural complexity and diversity, are on an increasing trend in our times. Accordingly, the accurate diagnosis and appropriate treatment for them are required. Especially in the current years, children's disorders delivered by the emotional problems keep increasing. In this research, the researcher tried to figure out the cause of the children's stress and its treatment, studied the theories of the stress in the modem medicine and the sever emotions in oriental medicine, and came to the conclusion as follows: 1. The stress can be defined as the combination of the reaction to noxious stimuli and its defense mechanism of the body, In oriental medicine, it is considered as pathological notions which includes seven emotions as the internal factor, six evils as the external factor and other foods, expectoration, ecchymoma as the non-internal/external factors. 2. Children usually get stressed by various reasons in a growth process such as schooling, relationship with friends, the opposite sex of family, or change of surroundings, and these can cause the various disorders. 3. In the study of the children's stress symptoms, it is found that the silent reaction is uncommon. It usually appeared in both reactions: firs, physical reactions such as stomachache, vomiting, headache, neural frequent urination, bronchial asthma or excessive respiration and/or, second, behavioral reactions such as a decline of performance, alimentary disorder, e.g. anorexia nervosa or bulimia, sleep disorder, e.g. nightmare or panic in sleep, anthrophobia, refusal to a school attendance or hyperactiveness. Besides, the peculiar mental disorder such as paroxysm of anger, tic, autism, nocturnal enuresis, lack of attentiveness, impediment in linguistic development, learning difficulty, intellectual decline, etc. can be appeared, and the heavy stress during the babyhood can cause the regression of behavior or the immaturity of formation of character. 4. The appropriate treatments for the children's stress are Osteopathy, Manpulation, Aroma Therapy, Alexander Technique, Autonomic Never Control Treatment, Biofeedback, Chiropractic, Dance Therapy, Feldenkrasis Technique, Gravity Therapy, Homepathy, Aquatherapy, Hypnotherapy, Naturopathy and Meditation.

승모판막질환에 동반된 심방세동에서 Cox-Maze 술식

김기봉,조광리,안혁,Kim, Ki-Bong,Cho, Kwang-Ree,Ahn, Hyuk 대한흉부심장혈관외과학회 1998 Journal of Chest Surgery (J Chest Surg) Vol.31 No.10

연구배경 : 심장의 구조적 이상을 동반하지 않는 만성 심방세동에 대한 Cox-Maze 술식의 성적은 매우 좋은 것으로 보고되고 있으나 승모판막 질환과 같은 기질적 심장질환에 동반된 심방세동에서의 성적은 다소 떨어지는 것으로 보고되고 있다. 대상 및 방법 : 본 서울대학교병원 흉부외과학 교실에서는 승모판막 질환에 대한 수술과 함깨 시행한 Cox-Maze 술식의 효과와 안전성을 평가하기위해 1994년 4월부터 1997년 10월까지 경험한 70례(남;23, 여;47)를 대상으로 임상 연구를 하였다. 결과 : 70례중 67례가 류마티스성 승모판막 질환이었으며 3례가 퇴행성 질환이었다. 술전 심방세동의 평균 유병기간은 66$\pm$70개월이었다. 15명의 환자에서 과거력상 혈전색전증의 병력이 있었으며 24명의 환자에서 수술중 좌심방내의 혈전이 존재하였다. 과거에 조직판막을 이용한 판막치환술의 병력이 있었던 재수술례가 12례였다. 수술시 대동맥차단시간은 평균 151$\pm$44분이었으며 심폐우회시간은 평균 246$\pm$65분이었다. Cox-Maze 술식과 함께 시행한 수술로는 승모판막 치환술이 19례,승모판막과 대동맥판막 치환술이 14례, 승모판막 치환술과 삼첨판막륜 성형술이 8례, 승모판막 치환술 및 대동맥판막 성형술이 3례있었으며 11례에서는 승모판막 성형술이 가능하였다. 판막치환술과 관상동맥우회술을 같이 시행한 례가 3례있었으며 승모판막 재치환술이 10례, 승모판막 및 대동맥 판막 재치환술이 2례 있었다. 수술사망률은 1.4%(1/70)였다. 수술후 합병증으로는 술후 일시적 심방세동의 재발을 보인 례가 44례였으며 상심실성 빈맥이 10례, 저심박출증후군이 4례, 출혈에 의한 재수술이 4례있었다. 그 밖의 합병증으로는 급성 신부전이 1례, 수술전의 일측 편마비가 악화된 경우가 1례, 그리고 일시적 섬망이 1례 있었다. 생존한 모든 환자를 평균 16.4개월간 외래를 통한 추적관찰하였는데 동기능부전 증후군과 빈맥-서맥 증후군을 보인 2명의 환자에서 영구형 심박동기의 삽입이 필요하였고, 2례만이 현재 심방세동을 보이고 있어서 동율동으로의 전환율은 94.2%였다. 수술만으로 심방세동이 조절되었던 경우가 73.9% 이었고, 수술후 항부정맥제의 병행 투약이 필요했던 경우가 20.3% 이었다. 술후 심방수축력과 기타 심기능의 평가를 위하여 시행한 경흉부 심초음파 검사 소견상 우심방 수축력은 92%에서, 좌심방 수축력의 회복은 53%에서 관찰되었다. 판막재치환술을 시행한 환자들을 첫 수술인 환자들과 비교하였을 때, 심방세동의 유병기간은 재수술한 례에서 통계적으로 유의하게 길었으나 대동맥차단시간, 심폐우회시간, 수술당일의 출혈량, 동율동으로의 전환율등에서는 차이가 없었다. 결론 : 결론적으로 승모판막 질환에 대한 수술과 함께 시행한 Cox-Maze 술식은 비교적 낮은 수술위험도 하에서 높은 동율동 전환률을 보였으며 특히 재수술시에도 비교적 안전하며 매우 효과적이었다. Background: The sugical results of the Cox-Maze procedure (CMP) for lone atrial fibrillation(AF) have proven to be exellent. However, those for AF associated with mitral valve(MV) disease have been reported to be a little inferior. Materials and methods: To assess the efficacy and safety of the CMP as a combined procedure with MV operation, we studied retrospectively our experiences. Between April 1994 and October 1997, we experienced 70 (23 males, 47 females) cases of CMP concomitantly with MV operation. Results: The etiologies of MV disease were rheumatic in 67 and degenerative in 3 cases. The mean duration of AF before sugery was 66$\pm$70 months. Fifteen patients had the past medical history of thromboembolic complications, and left atrial thrombi were identified at operation in 24 patients. Twelve cases were reoperations. Aortic cross clamp (ACC) time was mean 151$\pm$44 minutes, and cardiopulmonary bypass (CPB) time was mean 246$\pm$65 minutes. Concomitant procedures were mitral valve replacement (MVR) in 19, MVR and aortic valve replacement (AVR) in 14, MVR and tricupid annuloplasty (TAP) in 8, MVR with AV repair in 3, MV repair in 11, MVR and coronary artery bypass grafting (CABG) in 2, MVR and AVR and CABG in 1, redo-MVR in 10, redo-MVR and redo-AVR in 2 patients. The rate of hospital mortality was 1.4%(1/70). Perioperative recurrence of AF was seen in 44(62.9%), and atrial tachyarrhythmias in 10(14.3%), low cardiac output syndrome in 4(5.7%), postoperative bleeding that required mediastinal exploration in 4(5.7%) patients. Other complications were acute renal failure in 2, aggravation of preoperative hemiplegia in 1, and transient delirium in 1 patient. We followed up all the survivors for 16.4 months(3-44months) on an average. Sinus rhythm has been restored in 65(94.2%) patients. AF has been controlled by operation alone in 73.9% and operation plus medication in 20.3%. Two patients needed permanent pacemaker implantation; one with sick sinus syndrome, and the other with tachycardia- bradycardia syndrome. Only two patients remained in AF. We followed up our patients with transthoracic echocardiography to assess the atrial contractilities and other cardiac functions. Right atrial contractility could be demonstrated in 92% and left atrial contractility in 53%.We compared our non-redo cases with redo cases. Although the duration of AF was significantly longer in redo cases, there was no differences in ACC time, CPB time, postoperative bleeding amount and sinus conversion rate. Conclusions: In conclusion, the CMP concomitant with MV operation demonstrated a high sinus conversion rate under the acceptable operative risk even in case of reoperation.

지반가속도의 시뮬레이션과 강기반상(剛基盤上)에 설치된 회전측-베어링계의 지진해석

김기봉,Kim, Ki Bong 대한토목학회 1989 대한토목학회논문집 Vol.9 No.4

비선형 거동을 일으키는 구조물의 불규칙 진동해석이나 운동방정식이 매개여기와 비제차 여기를 포함하는 능동장비의 동적해석에는 불규칙 진동분야에서 보편적으로 사용되는 스펙트럼해법의 적용이 불가능하다. 만약 불규칙 입력하중을 인공적으로 시뮬레이션 할 수 있다면 이러한 문제들은 운동방정식에 직접적분법을 적용하여 동적응답을 얻을 수 있다. 본 논문에서는 FFT기법을 이용하여 비정상 불규칙 지반가속도를 시뮬레이션하는 효과적이고 실제적인 방법을 제시하며, 이렇게 얻은 인공지진을 응용하는 문제로서 지진하충을 받는 회전축-베어링계의 동적응답을 시뮬레이션하였다. 또한 시뮬레이션기법의 적용성 및 실용성을 검토하기 위한 민감도에 대한 연구도 제시하였다. The classical spectral analysis of random vibration is not applicable to the random vibration of nonlinear structures or the dynamic response of active mechanical systems whose governing equations contain random parametric and inhomogeneous excitations. If the random load is simulated, dynamic responses can be obtained with the application of numerical integration schemes to the governing equations of above problems. Thus, in this paper, efficient and practical methods of simulating nonstationary random seismic ground accelerations are presented by using the fast Fourier transform technique. Typical applications of the simulated ground accelerations are the simulations of the dynamic response of rotor-bearing systems under earthquake excitations. The study of accuracy is presented to determine the applicability and practicality of methods of simulation.

심폐바이패스없이 시행하는 관상동맥우회술

김기봉,임홍국,허재학,안혁,함병문,Kim, Ki-Bong,Lim, Hong-Gook,Huh, Jae-Hak,Ahn, Hyuk,Ham, Byung-Moon 대한흉부심장혈관외과학회 2000 Journal of Chest Surgery (J Chest Surg) Vol.33 No.1

Background: We analyzed the result of the "Off-Pump" Coronary Artery Bypass grafting (OPCAB) performed to minimize inflammatory responses to cardiopulmonary bypass and myocardial ischemia during the aortic cross-clamp period. Material and Method : The preoperative diagnosis operative procedure mortality complication and postoperative course of the 50 patients who underwent OPCAB between January 1998 and September 1998 were analyzed. There were 34 males and 16 females with mean age of 60$\pm$9 years. Preoperative clinical diagnoses were unstable angina in 31(62%) stable angina in 16(32%) and clinical diagnoses were unstable angina in 31(62%) stable angina in 16(32%) and postinfarction angina in 3(6%) patients. Preoperative angiographic diagnoses were three-vessel disease in 25(50%) two-vessel disease in 5(10%) one-vessel disease in 7(14%) and left main disease in 13(26%) patients. There were elective operation in 37 cases and urgent operation in 13 cases. Result: The mean number of grafts was 3.2$\pm$1.2 per patient. Grafts used were unilateral internal thoracic artery in 43 greater saphenous vein in 37 radial artery in 7 bilateral internal thoracic arteries in 4 and right gastroepiploic artery in 2 cases Forty sequential anastomoses were performed in 18 cases. Vessels accessed were left anterior descending artery in 48 diagonal branch in 41 obtuse marginal branch in 30 right coronary artery in 24 posterior descending artery in 9 ramus intermedius in 5 and posterolateral branch in 5 anastomoses. Predischarge coronary angiography performed in 44 patients demonstrated the patency rate of 89.5%(128/143) Operative mortality was 2%(1/150) Postoperative complications were arrhythmia in 5 graft occlusion that needed reoperation in 4. perioperative myocardial infarction in 2 femoral artery thromboembolism developed after the application of IABP in 1 postoperative transient delirium in 1 peripheral compression neuropathy in 1 case. Sixteen patients(32%) were extubated at the operating room and the other patients were extubated at the mean 13$\pm$20 hours after the operation. Mean duration of stay in intensive care unit was 49$\pm$46 hours. Thirteen patients(26%) required blood transfusions perioperatively and the amount of perioperative blood transfusion was mean 0.70$\pm$1.36 pack/patient. Conclusion: OPCAB is suggested to be the ideal technique with less postoperative complication less hospitalization time and less cost.less cost.

유전자 프로모터 예측을 위한 Support Vector Machine의 응용 방법에 대한 연구

김기봉,Kim, Ki-Bong 한국생명과학회 2007 생명과학회지 Vol.17 No.5

The high-throughput sequencing of a lot of genomes has resulted in the relatively rapid accumulation of an enormous amount of genomic sequence data. In this context, the problem posed by the detection of promoters in genomic DNA sequences via computational methods has attracted considerable attention in recent years since exact promoter prediction can give a clue to the elucidation of overall genetic networks. In this study, applications of support vector machine(SVM) to promoter prediction are explored to show a right approaches to discriminate between promoter and non-promoter regions by means of SVM. The results of various experiments show that encoding method, encoding region and learning data constitution can play an important role in the performance of SVM. 유전자의 구조 예측 및 발현 기작에 대한 연구는 매우 중요한 사안으로 대두되고 있다. 특히 유전자 발현 제어에 중요한 역할을 하는 프로모터 영역을 예측하는 것은 전체 생명체 네트워크 규명을 위한 단초를 제공하기 때문에 많은 연구가 이루어지고 있다. 본 논문에서는 이러한 진핵생물의 유전자 프로모터 예측을 위한 Support Vector Machine(SVM) 활용방안에 대한 연구내용을 다루고 있다. 특성 벡터 값 생성을 위한 인코딩 방법 및 학습 데이터들의 구성에 대한 다양한 실험을 통해 SVM활용 방안에 대한 올바른 방향을 제시하고 있다.

마황, 인삼, 택사 복합추출물의 endocannabinoid system 억제를 통한 비알콜성 지방간 유도 인슐린저항성 개선 효과

김기봉,안상현,Kim, Ki Bong,Ahn, Sang Hyun 대한한방소아과학회 2020 대한한방소아과학회지 Vol.34 No.4

Objectives This study aimed to investigate the efficacy of Ephedra sinica (E. sinica), Panax ginseng (P. ginseng), and Alisma orientale (A. orientale) Extract (MIT) on insulin resistance induced by Non-alcoholic fatty liver disease (NAFLD). Methods C57BL /6 male mice (8-week-old, 20 g) were divided into four groups: control group (Ctrl), high-fat diet group (HFDF), high fat diet with metformin administration group (METT), and high fat diet with MIT administration group (MITT). Each 10 mice were allocated to each group (a total of 40 mice). All mice were allowed to eat fat-rich diet freely throughout the experiment. To examine the effect of MIT, we observed Cannabinoid receptor type 1 (CB1), Cannabinoid receptor type 2 (CB2), G protein-coupled receptor 55 (GPR55), and Transforming growth factor-β (TGF-β). Results In the MITT group, positive reactions of the CB1, CB2, and GPR55 were significantly was significantly suppressed compared to the HFDF group. The positive reactions of the CD36 and TGF-β in the liver tissue were significantly suppressed in MITT. Conclusions MIT has the effect of improving NAFLD induced insulin resistance through the regulation of the lipid metabolism.

Cox-Maze III 술식의 변형

김기봉,허재학,장지민,이정상,안혁,손대원,Kim, Ki-Bong,Huh, Jae-Hak,Chang, Ji-Min,Lee, Jeong-Sang,Ahn, Hyuk,Sohn, Dae-Won 대한흉부심장혈관외과학회 2000 Journal of Chest Surgery (J Chest Surg) Vol.33 No.11

배경: Cox-Maze III (CM-III) 술식은 복잡한 심방 절개로 인한 긴 수술시간 때문에 다른 개심 수술과 병행하여 시행하기 어려운 단점이 있다. 대상 및 방법: 저자들은 CM-III 술직을 다음과 같이 변형하여 시행하고 그 임상성적을 분석하였다. \circled1 좌심방이를 절제하는 대신 좌심방이를 외부에서 결찰하고, \circled2 폐정맥 분리 절개선과 좌심방이 사이에 냉동절제술을 시행하며, \circled3 우심방이를 절제하는 대신에 우심방 외측 절개선을 우심방이까지 연장하고, \circled4 후종 우심방 절개 하부에서 우심방 외측을 지나 삼첨판막륜으로 향하는 T-자 절개선을 생략하였다. 저자들이 시행한 변형 술식의 용이성과 효율성을 평가하기 위하여, 우리나라에서도 빈도가 높은 류마치스성 승모판막 질환에서, 전통적인 Cox-III 술식(그룹 I)의 임상결과와, 변형된 CM-III 술식(그룹 II)의 임상결과를 비교하였다. 결과: 그룹 I(n=18)에서 동반된 수술은 승모판막 치환술 10례, 승모판막 성형술3례, 승모판막 치환술과 삼첨판막륜 성형술3례, 승모판막 재치환술 2례 등이었다. 그룹II(n=23)에서 동반된 수술은 승모판막 치환술 7례, 승모판막 성형술 5례, 승모판막 치환술과 삼첨판막륜 성형술 1례, 승모판막 재치환술 10례 등이었다. 그룹 I과 그룹 II에서 평균 대동맥 차단 시간(ACC)은 각각 135$\pm$29분과 104$\pm$18 분, 심패바이패스(CPB) 시간은 각각 240$\pm$33분과 185$\pm$42분이었다. 그룹 I과 그룹 II의 평균 추적 관찰 기간은 각각 47$\pm$14 개월과 29$\pm$4 개월이었다. 그룹 I에서는 16례(88.9%)에서 정상 동율동으로 회복되었고 1례에서 심방세동이 남아 있었으며, 다른 1례는 서맥증후군(sick sinus syndrome)으로 인공 심박조율기를 삽입하였다. 그룹 II에서는 21례(91.3%)에서 정상 동율동으로 회복되었고 2례는 심방세동이 지속되었다. 그룹 I에서 정상동율동으로 회복된 16례는 100%(16/16)에서 우심방의 수축을 심장 초음파검사에서 확인할 수 있었으며, 좌심방의 수축은 75%(12/16)에서 확인할 수 있었다. 그룹 II에서는 정상 동율동으로 회복된 21례 중 100%(21/21)에서 우심방의 수축을 확인할 수 있었으며, 좌심방의 수축은 76.2%(16/21)에서 확인할 수 있었다. 결론: 변형 CM-III 술식은 전통 CM-III 술식에 비하여 ACC time(p<0.005)과 CPB time(p<0.001)을 의미있게 줄이면서도 필적할 만 한 정상 동율동 전환율과 심방 수축력의 회복을 보여주었다.

아토피피부염에서 갈근황금황련탕 추출물의 ECS 조절을 통한 염증 완화 효과

김기봉,안상현,Kim, Ki Bong,Ahn, Sang Hyun 대한한방소아과학회 2021 대한한방소아과학회지 Vol.35 No.4

Objective The purpose of this study was to confirm the effects of Galgeunhwanggeumhwangryeon-tang in reducing inflammation through the endocannabinoid system (ECS) control in atopic dermatitis. Methods 8-week-old Balb/C mice were divided into 4 groups: contorl group (Ctrl), lipid barrier elimination group (ADE), palmitoylethanolamide treated group after lipid barrier elimination (PEA), and Galgeunhwanggeumhwangryeon-tang applied group after lipid barrier elimination (GGRT). After inducing atopic dermatitis, cannabinoid receptor (CB) 1, CB2, CD68, phosphorylated inhibitor kappa B (p-IκB), inducible nitric oxide synthase (iNOS), substance P and serotonin were observed to confirm the regulation of the ECS, macrophage activity and mast cell activity. Results CB1 and CB2 showed higher positive reactions in the GGRT than in the LBE and PEA. CD68, p-IκB and iNOS showed higher positive reaction in the LBE, PEA and GGRT than in the Ctrl, but the increase in the positive reaction was lower in the GGRT compared to the LBE and PEA. Substance P and serotonin showed higher positive reaction in the LBE, PEA and GGRT than in the Ctrl, but the increase in the positive reaction was lower in the GGRT compared to the LBE and PEA. Conclusions The effects of Galgeunhwanggeumhwangryeon-tang were confirmed though the regulation of the ECS, macrophage activity and mast cell activity.