실험 오차가 주파수 응답함수에 미치는 영향

정해일 ( Hae Il Jung ) 한국실천공학교육학회 2011 실천공학교육논문지 Vol.3 No.1

유한요소 해석(FEA: finite element analysis)의 발달로 복잡한 기계나 자동차 및 구조물에 대해서도 상세한진동해석을 할 수 있게 되었다. 그러나, 복잡한 구조물을 정확하게 모형화하기 어렵고, 특히 접합부의 강성과 감쇠 특성을 알기 어렵고, 복잡한 형상을 단순화하는 과정에서 발생하는 오차 등의 이유로 유한요소해석 결과는 부정확할 수 있다. 반면에 실제 구조물의 실험 데이터로부터 추출한 실험적 모드해석(modal testing) 결과는 상세하지는 않지만 정확하다고 볼 수 있다. 그러나 실험 결과가 구조물의 진동 특성을 정확하게 나타낸다는 가정은 여러 가지 측정 오차로 인하여 정확하지 않을 수 있다. 이 논문에서는 실험적 모드해석의 기본이 되는 FRF(frequency response function; 주파수 응답함수)의 측정에 영향을 미치는 오차들을 측정 오차와 신호처리 오차로 구분하여 각각에 대해 세밀히 살펴보고, 그러한 오차들을 감소함으로써 보다 정확한 FRF를 구하는 방법에 대해서 고찰해보았다. Despite the highly sophisticated development of finite element analysis, a finite element model for structural dynamic analysis can be inaccurate or even incorrect due to the difficulties of correct modelling, uncertainties on the finite element input data and geometrical oversimplification, while the modal data extracted from measurement are supposed to be correct, even though incomplete. The assumption that the test results represent the true dynamic behaviour of the structure, however, may not be correct because of various measurement errors. The measurement errors are investigated and their effects on estimated frequency response functions(FRFs) are also investigated.

유한요소해석을 통한 브레이크 디스크의 열변형 현상 고찰

정해일(Hae-il Jung),김형만(Hyung-man Kim),최갑승(Kap-seung Choi) 한국자동차공학회 2004 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-

Thermal judder has been effected by the thermal deformation of the brake disk. High friction heat is generated during braking and concentrated to particular regions of the brake disk. The heat is transferred to the air through the brake disk. Because the temperature distribution on the disk is irregular, thermal deformation has been occurred during braking. In this study, thermal deformation analysis of brake disk by FEM has been practiced. The results of the analysis show the deformed shape and temperature distribution of the brake disk. The deformed shape due to the thermal judder has been verified at the early stage of the braking.

나선형 홈이 있는 브레이크 디스크의 열탄성불안정성에 대한 수치해석

정해일(Hae-Il Jung),최갑승(Kap-Seoung Choi),강일환(Il-Hwan Kang),왕학민(Hak-Min Wang),김형만(Hyung-Man Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

The brake disc is the thermoelastic instability by the frictional heating during braking. In the present paper, the helical grooved vent brake disc is proved the thermoelastic instability by numerical analysis. The FEM analysis had been practiced for the comparisons of the thermoelastic instability and thermal deformation between the helical grooved vent brake disc and the conventional one.

학교 집단 소변 검사로 발견 된 막증식성 사구체신염 I형의 특성

최정연,박미영,이용직,하일수,정해일,최용,박영서,한혜원,진동규,정우영,김기혁,유기환,박용훈,Choi, Jung-Youn,Park, Mi-Young,Lee, Yong-Jik,Ha, Il-Soo,Cheong, Hae-Il,Choi, Yong,Park, Young-Seo,Han, Hye-Won,Jin, Dong-Kyu,Chung, Woo-Yeong,Kim, Ke 대한소아신장학회 2006 Childhood kidney diseases Vol.10 No.2

Purpose : In Korea, the school urine screening program is a useful tool for screening urine abnormalities. It is particularly useful in early detection of membranoproliferative glomerulonephritis(MPGN) I, which frequently progresses to chronic renal failure. In this study, we studied the medical history, laboratory findings, and histologic findings of MPGN to gain helpful information on early detection and treatment. Methods : The subjects were 19 children, who were diagnosed with MPGN from kidney biopsies that were performed in ten nationwide university hospitals because of abnormal urine findings from school urine screening programs conducted from July 1999 to April 2004. We divided the patients into 2 groups, a nephrotic range proteinuria group(n=8) and a non-nephrotic proteinuria group(n=11), and retrospectively analyzed the clinical features, laboratory findings, histologic findings, treatment, and clinical course. Results : The mean age at the first abnormal urinalysis was $10.6{\pm}2.2$ years in the nephrotic proteinuria group and $9.6{\pm}3.2$ years in the non-nephrotic proteinuria group. The mean age at the time of kidney biopsy was $11.3{\pm}2.3$ years in the nephrotic range proteinuria group and $10.4{\pm}3.2$ years in the non-nephrotic proteinuria group respectively. There was no significant difference in the mean age and sex between the two groups. In the nephrotic proteinuria group, 6 children had a low plasma C3 level and in the non-nephrotic proteinuria group, 8 children had a low plasma C3 level, but there was no significant difference between the 2 groups. There was no significant difference in the laboratory test results(including WBC count, RBC count, platelet count and other serologic tests) between the 2 groups except for 24 hour urine protein secretion. There was no difference between the 2 groups with regard to the acute and chronic changes in the glomerulus on light microscopic findings, IgG, IgA, Ig M, C1q, C3, C4, fibrogen deposition on immunofluoroscence findings, and mesangial deposits, subendothelial deposits, and subepithelial deposits on electron microscopic findings. The children were treated with corticosteroids, ACE(angiotensin-converting enzyme) inhibitors, dipyridamole and other immunosuppressive agents. During the course of treatment, there were no children whose clinical condition worsened. Among 19 children, 3 children went into remission(2 in the nephrotic proteinuria group, 1 in the non-nephrotic proteinuria group) and 9 children went into a partial remission(4 in the nephrotic proteinuria group, 5 in the non-nephrotic proteinuria group) on urinalysis. There was no significant difference in the treatment results between the two groups. Conclusion : The 73.7% of children who were incidentally diagnosed with MPGN by the school urine screening program had reduced C3. 42.1% of the children had nephrotic range proteinuria. There were no significant differences in clinical features, laboratory test results, light microscopic, immunofluorescence microscopic, and electron microscopic findings between the nephrotic proteinuria group and the non-nephrotic proteinuria group except for the 24 hour urine protein secretion. Therefore, for early detection of MPGN during the school urine screening program, we strongly recommend a kidney biopsy if children have abnormal urine findings such as persistent proteinuria and persistent hematuria, or if the serum C3 is reduced.

신생아 신정맥 혈전증 2례

임중섭,백경훈,한효정,이준호,정해일,최용,고광욱,김인원,Lim Jung-Sub,Paek Kyong-Hoon,Han Hyo-Jung,Lee Jun-Ho,Cheong Hae-Il,Choi Yong,Ko Kwang-Wook,Kim In-One 대한소아신장학회 1997 Childhood kidney diseases Vol.1 No.2

Renal venous thrombosis (RVT) in neonatal period is a rare disease and usually complicated to clinical situations with reduced renal blood flow and hypercoagulability ; like acute blood loss, sepsis, shock, and birth asphyxia. RVT should be suspected in sick babies with hematuria, anemia, thrombocytopenia, enlarged kidney and acute renal failure. And the diagnosis can be confirmed by renal ultrasonography. We report two cases of neonatal renal venous thrombosis with review of literatures. One case, associated with E. coli sepsis, recovered completely, and the other, follwed respiratory distress in the neonate, revealed permanent renal functional impairment.

비례제어방식 솔레노이드 동적거동에 관한 수치해석

태혁준(Hyeok-jun Tae),정해일(Hae-il Jung),김형만(Hyung-Man Kim),이현우(Hyun-woo Lee) 한국자동차공학회 2003 한국자동차공학회 지부 학술대회 논문집 Vol.2003 No.10

In the present paper, dynamics analyses of pressure control characteristics have been performed in a variable pressure solenoid valve. A number of solenoid valves have been used in the electronic control system, especially automatic transmission of an automobile. Variable pressure solenoid valve is intended to produce spatial movement by the electrical signal. Dynamics analyses of pressure control characteristics have been practiced by the Finite Difference Method, which show the pressure distribution in the solenoid valve. The results of numerical analyses show the dependence of pressure distribution on the displacement of the spool in the solenoid valve, and then, are compared with the experimental results.<br/>

투석 치료중인 만성 신부전 소아에서의 지질 및 지질단백 이상

김정수,송정한,박혜원,정해일,김진규,최용,고광욱,Kim Jung-Sue,Song Jung-Han,Park Hye-Won,Cheong Hae-Il,Kim Jin-Q,Choi Yong,Ko Kwang-Wook 대한소아신장학회 1997 Childhood kidney diseases Vol.1 No.2

목적 : 말기 신부전 환자에서 심혈관계 질환은 유병율 및 사망율의 중요한 원인중 하나이다. 이들 환자에서 흔히 동반되는 고지질단백 혈증은 심혈관계 질환의 위험인자로 작용하며, 특히 lipoprotein(a)[Lp(a)]는 관상동맥 질환과 혈전증의 위험 인자로 알려져 있다. 소아에서도 만성 신부전시 고지질 혈증이 보고되어 있다. 저자들은 투석 치료중인 만성 신부전 소아를 대상으로 혈중 지질, 지질단백 및 Lp(a)의 농도 변화를 분석하였다. 방법 : 서울대학교 어린이병원 소아과에서 유지 혈액 투석을 받고 있는 환아 10명과 지속성 외래 복막 투석을 받고 있는 환아 14명을 대상으로 정맥 혈청중 지질, 지질단백 및 Lp(a)농도를 측정하여 건강 대조군과 비교하였으며, Lp(a)의 혈중 농도에 따른 다른 지질단백의 혈중 농도를 비교하였다. 혈액투석(hemodialysis, HD)환아군의 평균 연령이 $162{\pm}59$ 개월, 남녀비는 7:3 이었으며 복막투석(peritoneal dialysis, PD)환아군의 평균 연령은 $123{\pm}69$개월, 남녀비는 6:8 이었다. 결과 : 1) 연령, 성별, 비만지수, 투석기간은 HD군과 PD군 간의 차이가 없었으나 혈중 단백과 알부민치는 PD군에서 유의하게 낮았다. 2) HD군과 PD군 모두에서 혈중 콜레스테롤, 중성지방, 저비중 지질단백 콜레스테롤(low density lipoprotein-cholesterol, LDL-콜레스테롤)과 고비중 지질단백 콜레스테롤(high density lipoprotein-cholesterol, HDL-콜레스테롤)의 비는 대조군에 비해 증가되어 있었으며, HDL-콜레스테롤과 콜레스테롤의 비는 대조군에 비해 유의하게 낮았다. 3) 혈중 아포단백 B치는 대조군에 비해 상승되어 있었지만 아포단백 Al과 아포단백 B의 비는 차이가 없었고, 혈중 Lp(a)치는 PD군에서만 대조군보다 상승되어 있었다. 4) 혈중 Lp(a)치가 30 mg/dl 미만인 환아는 13명, 30 mg/dl 이상인 환아는 11명으로 이들 간에 연령, 비만지수, 투석방법, 투석기간은 차이가 없었으나 혈중 알부민은 Lp(a)가 상승된 환아들에서 감소되어 있었다. 5) 혈중 Lp(a)농도와 다른 지질 단백과의 비교에서 아포 단백 B만이 유의한 차이를 보였다. 결론 : 투석 치료중인 만성 신부전 소아에서 혈중 지질단백 이상이 관찰되었으며 특히 PD군에서는 혈중 Lp(a)치가 증가되어 있었다. 따라서 만성 신부전 소아에서 관상 동맥 질환의 위험도가 높을 것으로 사료되며 이에 대한 장기적이고 지속적인 관찰이 필요하다. Purpose : Chronic renal failure is often accompanied by severe dyslipidemia, a known risk factor for cardiovascular disease. Lipoprotein(a) [Lp(a)] has recently been characterized as a risk factor for atherosclerosis and thrombosis. Cardiovascular disease is the leading cause of death in adult patients on dialysis. However, there are only limited data available concerning risk factors for atherosclerosis in uremic children. We have measured serum levels of lipids, lipoproteins, apolipoproteins and Lp(a) in uremic children with maintenance dialysis. Methods : Ten uremic children with hemodialysis (HD) and 14 with peritoneal dialysis (PD) in our dialysis unit were included in this study. The mean age of HD patients was $162{\pm}59$ months and the male to female ratio was 7:3. The mean age and sex ratio of PD patients were $123{\pm}63$ months and 6:8, respectively. The levels of cholesterol, triglyceride, lipoproteins, apolipoproteins and Lp(a) were measured from serum sampled after 14 hours of fasting. The normal control levels were cited from 2 articles presenting the normal blood lipid and lipoprotein levels of primary school and middle school children in Korea. Results : There was no difference in age, sex ratio, body mass index and duration of dialysis between the HD and the PD group. The serum concentration of the cholesterol, triglyceride and apolipoprotein B were significantly elevated in dialysis patients compared with normal subjects. The serum level of Lp(a) was significantly elevated in only PD group. The serum Lp(a) level was below 30 mg/dl in 13 and above 30 mg/dl in 11 patients. The serum albumin level was significantly decreased in high Lp(a) group than in low Lp(a) group. Conclusion : The uremic children receiving dialysis reveal abnormal serum lipid and lipoprotein profiles. These results suggest that they have a higher risk for coronary heart disease, although there has been no clinical evidence of coronary heart disease at present. A long-term follow-up study of these children to clarify the suggestion should be started now.

밀폐유도용해로 제조된 CoSb(3-y)Sny의 열전특성

박관호 ( Kwan Ho Park ),정해일 ( Hae Il Jung ),어순철 ( Soon Chul Ur ),김일호 ( Il Ho Kim ) 대한금속ᆞ재료학회 2007 대한금속·재료학회지 Vol.45 No.1

소아 복막 투석 환자에서 발생한 복막염: 단일기관에서 10년간의 경험

이세은,한경희,정윤혜,이현경,강희경,정해일,하일수,Lee, Se-Eun,Han, Kyoung-Hee,Jung, Yun-Hye,Lee, Hyun-Kyung,Kang, Hee-Gyung,Cheong, Hae-Il,Ha, Il-Soo 대한소아신장학회 2010 Childhood kidney diseases Vol.14 No.2

목 적 : 복막염의 원인균과 항생제 감수성은 지역이나 병원에 따라 다양하다. 따라서 이에 대한 자료가 치료 지침의 수립에 반드시 필요하다. 본 연구는 최근 10년동안 복막 투석을 받은 소아 환자들에서 발생한 복막염의 발생 빈도와 원인균의 특성의 변화를 알아보기 위해 수행되었다. 방 법 : 2000년부터 2010년까지 서울대학교 어린이병원에서 복막 투석을 받은 110명의 소아 환자들을 대상으로 하여 의무기록을 후향적으로 분석하였다. 결 과 : 복막 투석을 받은 환자 110명 중 57명에서 140례의 복막염이 발생하였다. 복막염의 발생 빈도는 0.43회/환자 년이었고, 2003년 이후로는 비슷한 빈도로 발생하고 있다. 60%의 환자가 복막 투석 시작 후 첫 1년 이내에 복막염이 발생하였고, 1세 미만에 복막 투석을 시작한 환아 7명은 모두 복막염을 경험하였다. 원인균으로 그람 양성균, 그람 음성균, 진균이 각각 58%, 38%, 4.1% 였고, 배양 음성률은 13.6% 였다. 그람 양성균 중에는 Staphylococcus, 그람 음성균 중에는Pseudomonas와Acinetobacter가 가장 많이 동정되었다. 그람 양성균중 56%가에는 1세대 cephalosporin에 감수성을 보였고, 그람 음성균 중 91%가 ceftazidime에 감수성을 보였다. 결 론 : 앞으로 복막염의 빈도를 더욱 감소시키기 위한 새로운 돌파구가 필요하다. 영아에서 복막염이 더 잘 발생하였지만, methicillin에 대한 저항성은 2세 미만에서 유의하게 높지 않았다. 전국적인 공동연구를 통해 우리나라 실정에 맞는 경험적 항생제 사용 지침을 정하는 것이 필요하다고 생각된다. Purpose : The organisms causing peritonitis and their antibiotic sensitivities vary in different regions and centers, and these data are necessary to establish regional treatment guidelines. The aim of this study was to investigate the changes in incidence and characteristics of the organisms that cause peritonitis in children undergoing peritoneal dialysis (PD) during recent 10 years. Methods : We retrospectively collected and analyzed the data from medical records of 110 children on PD during the period from 2000 to 2010. Results : One hundred and forty episodes of peritonitis have occurred in 57 patients. The overall incidence of peritonitis was 0.43 episodes/patient year, and similar incidence have been maintained since 2003. Sixty percent of the patients experienced peritonitis within 1 year of PD, and all patients commencing PD in infancy experienced peritonitis. Gram positive (G (+)), gram negative (G (-)) organisms and fungi were cultured in 58%, 38%, and 4.1% respectively and cultures were negative in 13.6%. Staphylococcus was the most common G (+) organism, and Pseudomonas and Acinetobacter were 2 most frequent G (-) organisms isolated. Fifty-six percent of the G (+) organisms were sensitive to first generation cephalosporin and 91% of G (-) pathogens were sensitive to ceftazidime. Methicillin-resistance rate was not higher in children less than 2 years of age than in those more than 2 years. Conclusion : An additional breakthrough has to be made to further reduce the incidence of peritonitis. Treatment guideline customized for peritonitis in Korean children on PD need to be established through a nationwide co-work.

복막 투석 중인 신증후군 환자의 복막을 통한 단백 소실

안요한,정의석,이세은,이현경,이소희,강희경,하일수,정해일,최용,Ahn, Yo-Han,Jung, Eui-Seok,Lee, Se-Eun,Lee, Hyun-Gyung,Lee, So-Hee,Kang, Hee-Gyung,Ha, Il-Soo,Jung, Hae-Il,Choi, Yong 대한소아신장학회 2009 Childhood kidney diseases Vol.13 No.2

목적 : 신증후군에서 사구체 단백 투과성이 증가하는 것은 전신적인 순환 인자와 관련되어 있는 것으로 여겨진다. 전신적인 순환 인자의 사구체 외 기관에서의 영향과 관련하여, 본 연구에서는 복막 투석 중인 steroid resistant nephrotic syndrome (SRNS) 환자에서의 복막투석을 통한 단백 소실 정도를 파악하고자 하였다. 방법 : 2001년부터 2009년까지 복막 투석 중인 신증후군 환자 12명(SRNS)과 대조군 14명을 대상으로 후향적 환자-대조군 연구를 시행하였다. 성별, 투석 시작 시 연령, 체중, 신장, 투석 방법, 투석양, 투석 시작 시 검사 소견(혈액 요소 질소, 혈청 크레아티닌, 혈청 단백, 혈청 알부민, 24시간 투석액 부피, 24시간 투석액 단백, Kt/V)과 1년 뒤 투석 시 검사 소견(24시간 투석액 단백)을 조사하였다. 단백질 섭취 정도를 평가하기 위해 nPNA (normalized protein equvalent of total nitrogen appearance)를 측정하였다. 결과 : SRNS군과 대조군은 nPNA를 비롯한 다른 지표에 의미 있는 차이를 보이지 않았으나, SRNS군에서 혈청 알부민이 $3.7{\pm}0.3$ g/dL로 대조군($4.0{\pm}0.4$ g/dL, P=0.021)보다 낮았다. 복막액을 통한 단백 소실량은 SRNS군에서 대조군보다 통계학적으로 의미 있게 높았으며($3,044.4{\pm}837.6\;mg/m^2$/day vs. $1,791.6{\pm}1,244.0\;mg/m^2$/day, P=0.007), 혈장 단백에 대한 복막의 투과성은 SRNS군에서 대조군보다 2배 가량 높았다($1.06{\pm}0.46%$ vs. $0.58{\pm}0.43%$, P=0.010). SRNS군과 대조군 모두 초기와 1년 뒤 복막 단백 소실량이 증가하였으나 대조군에서 더 큰 차이를 보였으며 복막 단백 소실량의 시간 경과에 따른 변화는 두 군(SRNS군 vs. 대조군)간에 의미있게 차이가 있었다(P=0.023). 결론 : 신증후군을 앓고 있는 소아 환자에서 복막 투석을 시행할 때는 이들의 영양상태, 성장 및 발달에 평가가 보다 적극적으로 이루어져야 하고, 복막을 통한 단백 소실을 모니터링하여 이를 보충하려는 노력 또한 필요하리라 생각된다. Purpose : The pathophysiologic mechanism of nephrotic syndrome is not yet known clearly. At least in some cases, certain 'circulating factors' are thought to increase the glomerular protein permeability. Considering the systemic effect of the circulating factor on peritoneal membrane, we evaluated the loss of protein through peritoneal membrane in patients on peritoneal dialysis due to the end stage renal disease (ESRD) caused by steroid resistant nephrotic syndrome (SRNS). Methods : We retrospectively reviewed the medical records of 26 pediatric patients on peritoneal dialysis ensued during the period from 2001 to 2007 at our clinic. Twelve patients had SRNS, while 14 patients had ESRD caused by the congenital anomalies of urinary system. Results : While the other parameters including nPNA indicating the adequacy of protein intake were similar between the two groups, serum albumin was lower in SRNS patients than the non-SRNS patients ($3.7{\pm}0.3$ g/dL vs. $4.0{\pm}0.4$ g/dL, P=0.021). Peritoneal protein loss was higher in SRNS patients than in non-SRNS patients ($3,044.4{\pm}837.6\;mg/m^2$/day vs. $1,791.6{\pm}1,244.0\;mg/m^2$/day, P=0.007). The protein permeability of the peritoneal membrane measured by the ratio of total protein concentration in dialysate to plasma was twice as high in SRNS patients as the non-SRNS ($1.06{\pm}0.46%$ vs. $0.58{\pm}0.43%$, P=0.010). After 1 year, peritoneal protein loss increased in both patient groups, but to a significantly greater degree in non-SRNS patient (P=0.023). Conclusion : The results of our study support the notion that in nephrotic syndrome there are some 'circulating factors' with the systemic effect. Since the greater protein loss through peritoneal membrane in SRNS was confirmed in this study, more meticulous nutritional support and close monitoring on the nutrition are required in these patients.