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.

고폐동맥압을 동반한 선천성 심기형 환자에서 술후 폐동맥압과 혼합정맥혈 산소분압의 변화에 관한 분석

김기봉,김용진,Kim, Gi-Bong,Kim, Yong-Jin 대한흉부심장혈관외과학회 1989 The Korean Journal of Thoracic and Cardiovascular Vol.22 No.6

It has been suggested that mixed venous $O_{2}$ tension is a predicor of cardiac output especially in a critically ill patient after an open heart surgery. From April 1988 through September 1989, we monitored mixed venous $O_{2}$ tension and pulmonary arterial pressure in 48 patients with acyanotic congenital heart disease at postoperative 1 hour, 6 hour, 12 hour, 24 hour, and 48 hour respectively. They were divided into Group I, with severe pulmoary hypertension, and Group II, without severe pulmonary hypertension. In Group I, mixed venous $O_{2}$ tension and cardiac index showed significant increase with time (p<0.05), but the ratio of pulmonary-aortic systolic pressure didn't show significant change. The increase was significant only 24 hour after operation, and so this low cardiac performance in early postoperative period should be considered when postoperative management is being planned in the risky patient. In Group II, all of the three variables didn't show any significant change with time. The correlation coefficient between mixed venous $O_{2}$ tension and cardiac index was significantly different from zero in both Group I (p<0.001) and group II (p<0.05) at each imeperiod, but the ratio of pulmonary-aortic systolic pressure didn't correlated well with the other 2 variables. Our study showed that serial determination of mixed venous $O_{2}$ tension in acyanotic congenital heart disease could be used as a guide in estimating the cardiac index postoperatively.

관상동맥우회술 후 1년 개존성에 관한 연구

김기봉,김현조,성기익,Kim, Gi-Bong,Kim, Hyeon-Jo,Seong, Gi-Ik 대한흉부심장혈관외과학회 1997 Journal of Chest Surgery (J Chest Surg) Vol.30 No.12

1994년 7월부터 1995년 8월까지 서울대학교병원 흉부외과에서 시행한 관상동맥 우회술 78례 중 49례 (62,8%)에서 수술 1년 후 관상동맥 조영술을 시행하여 이식 혈관의 개존성을 조사하였으며, 수술 전,후 및 수술과 관련된 여러 위험 요소들이 개존성에 미치는 영향에 대하여 분석하였다. 관상동맥 우회술 후 평균 13.4$\pm$2.1개월 째에 관상동맥 조영술을 시행하였다. 내유동맥으로 문함을 시행한 60개소 중 3개소에서 string sign을 보였으나, 폐쇄 없이 전례에서 개존성이 유지되었으며, 요골동맥으로 문합을 시행한 4개소는 모두 개존성이 유지되었다. 복제정맥으로 문합을 시행한 81개소 중 69개소(85.2%)에서 개존성이 유지되었으며, 12개 소(14.8%)에서 폐쇄되었다. 개존성에 미치는 위험요소로 수술 전,수술 중 그리고 합병증 등의 수술 후 요소로 나누어 일원적 및 다원적으로 분석하였으며, 내유동맥의 협착 과 복재정맥의 개존성, 폐쇄에 미치는 요소들을 분석하였다. 내유동맥은 환자의 연령(60세 이상),수술 후 대동맥 내 풍선펌프의 삽입,수술 후 출혈, 및 급성신부전 등 합병증이 이식 혈관의 협착과 관련된 위험 인자였으며, 복제정맥은 우회술을 시\ulcorner 받은 관상동맥의 직경이 1.5mm 이하인 경우가 이식 혈관의 폐쇄 위험성과 관련된 위험 인자로 분석되었다(p<0.05). 관상동맥 우회술 1년 후 이식 혈관의 개존성은 내유동맥이 복재정맥보다 우수함을 보였으며 환자 연령 수술 후 대동맥 내 풍선펌프의 삽입여부, 출혈, 급성 신부전 등의 합병증 및 문합된 관상 동맥의 직경 등이 개존에 관련된 요소로 분석되었다. 이러한 결과를 토대로 수술 후 이식혈관의 폐쇄 여부에 대한 11측과 수술 방법이나 수술 후 환자의 추적 관찰에 도움을 줄 수 있으리라 생각된다. Between July 1994 and August 1995, 78 patients underwent coronary artery bypass graft at Seoul National University Hospital. Coronary angiogram was performed one year after coronary artery bypass graft in 49 patients(62.8%) for evaluation of the graft patency and analysis of the risk factors for graft occlusion. The patency rates of both the internal mammary artery and the radial artery grafts were 100% , although three internal mammary artery grafts(5.0%) were narrowed(string sign). And that of the saphenous vein grafts were 85.2%. Multivariate analysis for the preoperative, operative, and postoperative factors was done between the widely patent and the narrowed internal mammary artery graft groups, and between the patent and the occluded saphenous vein graft groups by the general linear models procedure. Patient's age($\geq$60 years), postoperative intraaortic balloon pump insertion, bleeding, and acute renal failure were found to be the significant risk factors for internal mammary artery graft narrowing, and coronary artery size(< 1.5 mm) was the significant risk factor for the saphenous vein graft occlusion (p<0.05) . This study confirms that the arterial graft is superior to the vein graft at one-year patency rate, and suggests the risk factors for graft occlusion during the first postoperative year. Knowledge of this study may provide a basis for estimating the risk factors for graft occlusion, and thereby modifying surgical strategy and postoperative surveillance.

Senning씨 술식에 의해 교정한 완전 대혈관전위증에서의 심전도 변화에 관한 연구

김기봉,노준량,Kim, Gi-Bong,No, Jun-Ryang 대한흉부심장혈관외과학회 1985 Journal of Chest Surgery (J Chest Surg) Vol.18 No.4

One of the most widely recognized problems in patients with TGA [transposition of the great arteries] after the Senning operation is the occurrence of arrhythmias. From June 1982 through October 1984, 22 patients, 11 with "simple" and 11 with "complex" TGA, underwent correction of TGA by a modification of the Senning operation designed to avoid dysrhythmias. 16 were males and 6 females, with ages ranging from 3 months to 27 months. [mean age 10.8 months] 7 patients [31.8%], 1 with simple TCA and 6 with complex TGA, died in the early post-operative period. The operative mortality was 9.1% in "simple" TGA, and 54.9% in "complex" TGA. There were 4 late deaths but only one of these patients died of a dysrhythmia as a possible factor. The standard ECG [Electrocardiography] checked preoperatively showed sinus rhythm in 17 [77.3%], 1 AV block in 5 [22.7%]. In 22 patients studied postoperative 1st day, the incidence of arrhythmias was 63.6%, with significant incidence compared with preoperative study. [P<0.05]. But, in 15 patients studied postoperatively at intervals from 1 month to 26 months, the incidence of arrhythmias was 26.7%, with no significant incidence compared with preoperative study [P>0.1]. Our results indicate that a modified Senning operation may reduce the frequency of surgically induced arrhythmias. The mean frontal plane P-wave axis also revealed significant deviation to the right side [P<0.05], compared with preoperative study. These findings raise the possibility that what has been called sinus rhythm postoperatively may have a different origin and conduction sequence from normal. But the rhythm seems to be functionally similar.rhythm seems to be functionally similar.

성별에 따른 청소년의 스마트폰 사용의 문제적 경험 관련 요인

김기봉,문원희,권명진,Kim, Ki-Bong,Moon, Weon-Hee,Kwon, Myoung-Jin 중소기업융합학회 2021 융합정보논문지 Vol.11 No.10

This study was conducted to identify factors related to the problematic experiences of smartphone use among adolescents according to gender. The subjects of this study were 54,603 male and female adolescents. This study data was analyzed using SPSS 25.0 program. As a result of this study, the relevant factors for the problematic experiences of smartphone use among male students were academic performance, economic level, counselors, fast food consumption frequency, depression, suicidal ideation, suicide plan, happiness, subjective body image, stress, and smartphone usage time. Drinking and smoking were found to be significant related factors only for female students. Therefore, in order to reduce the problematic experience of smartphone use, an intervention considering the influence factors according to gender is required. 본 연구는 성별에 따른 청소년의 스마트폰 사용의 문제적 경험과 관련된 요인을 파악하고자 시행되었다. 본 연구 대상자는 제13차(2017년) 청소년건강행태온라인조사에서 스마트폰 사용 문제적 경험 문항에 답한 남녀 청소년 54,603명이었다. 본 연구 자료는 SPSS 25.0 program를 이용하여 분석하였다. 본 연구 결과 남학생의 스마트폰 사용의 문제적 경험의 관련 요인은 학업성적, 경제수준, 고민을 상담해 주는 사람, 패스트푸드 섭취빈도, 우울, 자살사고, 자살계획, 행복, 주관적 신체상, 스트레스, 스마트폰 사용 시간이었다. 음주와 흡연은 여학생에게만 유의한 관련 요인으로 나타났고, 자살계획은 남학생에게서만 유의하게 나타났다. 그러므로 스마트폰 사용의 문제적 경험을 감소시키기 위해서는 성별에 따른 영향요인을 고려한 중재가 요구된다.

흉곽내로 전위시킨 골격근을 이용한 농흉의 외과적 치료

김기봉,박종호,Kim, Gi-Bong,Park, Jong-Ho 대한흉부심장혈관외과학회 1992 Journal of Chest Surgery (J Chest Surg) Vol.25 No.6

From August 1990 through December 1991, 14 patients[all males] underwent int-rathoracic muscle transposition of extrathoracic skeletal muscles to treat empyemas, 6 patients had tuberculous empyemas, 4 had chronic empyemas of unknown etiology, 3 had pos-tpneumonectomy empyemas, and 1 had postlobectomy empyema. 9 patients had associated bronchopleural fistulas, Their ages ranged from 22 to 67 years, with mean age of 45.1$\pm$17. 6[$\pm$S.D] years. The serratus anterior was transposed in 13 patients, the latissimus dorsi in 12. In 11 patients, both the serratus anterior and the latissimus dorsi were transposed. The omental flap also transposed in 3 patients. To reduce the dead space in the thoracic cavity, thr-oacoplasty was also carried out in 10 patients. The number of the partially resected ribs was 3.0$\pm$0.8[$\pm$S.D.]. All operations were single stage procedures, and all wounds were closed primarily, with no permanent tubes or chest wall openings. There was no hospital mortality, and so no subsequent operation has been required. Follow-up of the patients ranged from 5 to 16 months with a mean of 9.2$\pm$3.1[$\pm$S.D] months, All the patints had no further signs or symptoms of the original infection after discharge. We conclude that intrathoracic transposition of extrathoracic skeletal muscle is an excellent method of treatment for persistent, life-threatening intrathoracic infections.

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.

피지컬 컴퓨팅을 이용한 교육용 인터렉티브 지구본 시스템에 관한 연구

김기봉,양황규,Kim, Gi-Bong,Yang, Hwang-Kyu 한국전자통신학회 2011 한국전자통신학회 논문지 Vol.6 No.4

최근에 컴퓨팅 기술의 발달과 체감형 콘텐츠에 대한 관심이 높아지면서 교육기관과 문화 시설에서 유아 및 청소년들을 대상으로 한 체험 학습 및 엔터테인먼트적인 성향이 높은 체감형 시스템을 요구하고 있고 투자를 하고 있다. 본 논문에서는 RFID Reader와 Tag 간 1356MHz 대역을 사용하고, Arduino와 다양한 센서들도 함께 적용한 교육용 인터렉티브 지구본 시스템을 제안하였다. 센서가 부착된 능동형 태그를 지구본 속에 부착하는 방법을 이용하여, RFID Reader, Arduino 및 센서와 Google Earth COM API의 연동을 통한 피지컬(Physical) 컴퓨팅 교육용 시스템을 구성하였다. Recently, the development of computing technology and experiential content for the increased interest in education and cultural facilities to target children and young people experience learning and experiential entertainment systems require a high propensity to invest and are. In this paper, for the 13.56MHz band RFID Reader and Tag RFID technology using the proposed interactive educational globe. Active tags attached to sensors attached to the globe were presented in the RFID reader, arduino and sensors in conjunction with Google Earth COM API was constructed through the physical computing educational system.

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.

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.