형상인식을 적용한 용접 결함의 특징변수 추출

김재열,마상동,오성민,송경석,김양중,김창현,곽이구 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2

In this study, the researches classifying the natural flaws in welding parts are performed using the signal pattern classification method. For this purpose 500MHz storage digital oscilloscope including FFT function and enveloped waveform generator are used and the signal pattern recognition procedure is made up the digital signal processing, feature extraction, feature selection and classifier design. Specially it is composed with and discussed using the distance classifier is based in euclidean distance the empirical Bayesian classifier. In feature extracting, it is performed using the class-mean scatter criteria. And the signal Pattern classification method is applied to the signal pattern recognition problems of natural flaw that is porosity inclusion, slag inclusion, lack of penetration, lack of fusion. center crack, side crack, toe crack. root crack as the planar and volumetric flaw classification problem. According to this results, if appropriately learned the neural network classifier is better acquire the recognition rate of 86.31% above through it is different a little according to domain extracting the feature and the classifier

태아용 ECMO 시스템 개발

김재열,유신,마상동,김창현 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.1

태아를 자궁외에서 인공양수로 충만한 Chamber에 넣고 막형산화기와 체외순환용 회로를 제대동정맥에 연결함으로서 염소태아의 자궁외 생존 모델을 수립하였다. 염소태아의 자궁외 최장 생존시간은 48시간이었으며, 염소태아의 자궁외 생존을 위한 혈류역학적, 혈액화학적 기초자료를 분석하였다. 태아의 자궁외 생존에 필요한 ECMO 순환 혈류량은 223±15.2㎖/min이었으며 태아생존률 및 태아생존시간에 체온, 마취시간, 태아체중 및 수술 숙련도등이 관계가 있었다. 인공양수를 채운 인공자궁 Chamber와 펌프, 막형산화기, 회로등이 연결된 인공 자궁태반의 프로토 타입을 고안 개발함으로서 동물모델에 의한 추가적인 연구를 가능하게 하였고, 합병증의 연구 및 태아영양공급과 발육문제등을 보완연구함으로서 인간에게 인공자궁태반이 실현될 수 있는 기반연구를 수행하였다. The ECMO system using umbilical cord and membrane type oxygenator which was connected with extracorporeal circulation unit was studied for the development of fetus growth model for goat. Maximum survival time of goat fetus was 48hour and its basic data of blood blow dynamics and chemical compositions were analyzed. Average blood rate required for the extracorporeal circulation was 223±15.2 ㎖/min and survival rate and survival time of fetus was deeply related to body temperature, total anesthetized time, fetus weight and skill for the surgery. The newly developed ECMO model for fetus corrected the problem of previously used ECMO that high pressure pump directly delivered to that fetal heart by installing reservoir bag. By applying the result from this new ECMO model. Further reserach will help to apply the system to human.

Prevention of Adjacent Segmental Disease after Fusion in Degenerative Spinal Disorder: Correlation between Segmental Lumbar Lordosis Ratio and Pelvic Incidence–Lumbar Lordosis Mismatch for a Minimum 5-Year Follow-up

Whoan Jeang Kim,Chang Hyun Ma,Sang Ha Kim,Yeon Seung Min,Jae Won Lee,Shann Haw Chang,Kyung Hoon Park,Kun Young Park,Dae Gun Song,Won Sik Choy 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4

Study Design: Retrospective study. Purpose: Associations among risk factors related to adjacent segmental disease (ASD) remain unclear. We evaluated the risk factors and segmental lordosis ratio to prevent ASD developing after lumbar spinal fusion. Overview of Literature: Risk factors related to ASD development are age, sex, obesity, pre-existing degeneration, number of fusion segments, and decreased postoperative lumbar lordosis (LL). However, the associations among these factors are still unclear and should be clearly identified. Methods: We retrospectively reviewed data on 274 patients who underwent lumbar spinal fusion of three segments or below for lumbar degenerative disease from January 2010 to December 2012, with over 5 years of follow-up. Patients with preoperative sagittal vertical axis (SVA) >5 cm were excluded due to sagittal imbalance. A total of 37 patients with ASD and 40 control patients (CTRL) were randomly selected in a similar distribution of matching variables: age, sex, and preoperative degenerative changes. Sex, age, number of fusion segments, radiologic measurements, L4–5–S1/L1–S1 LL ratio, and spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and SVA) were analyzed. Logistic regression was used to analyze the correlation between PI–LL mismatch and L4–5–S1 segmental lordosis rate. Results: No significant difference was found between ASDs and CTRL groups regarding age, sex, number of fusion segments, fusion method, and preoperative and postoperative spinopelvic parameters (PI, SS, PT, and LL). However, regarding the L4–5–S1/L1–S1 lordosis ratio, 50% (p=0.045), 60% (p=0.031), 70% (p=0.042), 80% (p=0.023), and 90% (p=0.023) were statistically significant; <20% (p=0.478), 30% (p=0.223), and 40% (p=0.089) were not statistically significant. In the postoperative PI–LL <10 group, ASD occurred less frequently than in the PI–LL >10 group, and the difference was statistically significant (p=0.048). Conclusions: Patients with a postoperative L4–5–S1/L1–S1 lordosis ratio >50% had less occurrence of ASD. Correcting LL according to PI and physiologic segmental lordosis ratio is important in preventing ASD.

세탁기용 자동변속기(Auto-Transmission)의 이상음 검사용 자동화 프로그램 개발

김재열,김양중,한재호,마상동,김창현 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1

This study includes automatic program for noise inspection of auto-transmission for washing machine one of modern home necessary. We effort to find and certificate sound noise source by sound power and sound intensity, and apply to frequency analysis in vibration related sound noise. Still more we have been studying to data acquisition and programming for MS VisualBasic version 5.0. System component is below. 1) Pentium PC for data acquisition. 2) DSO for noise acquisition. 3) S/W for comparison and decision. 4) I/F Board for data communication. Wave form data through the DSO are converting to ASCII code data. The ASCII code through binary converting S/W are to be decision fitness or the badness comparison S/W. Finally, we will making noise monitoring system and automatic program for inspection system

인지 및 행동영역에서 교대 근무의 유해적인 영향 : 비판적 고찰

이수지,박창현,하은지,박신원,홍혜진,박수현,마지영,강일향,강한,송병훈,김정윤,김지은,Lee, Suji L.,Park, Chang-hyun,Ha, Eunji,Park, Shinwon,Hong, Haejin,Park, Su Hyun,Ma, Jiyoung,Kang, Ilhyang,Kang, Hahn,Song, William Byunghoon,Kim, Jungyo 대한생물정신의학회 2017 생물정신의학 Vol.24 No.2

Shift workers experience a disruption in the circadian sleep-wake rhythm, which brings upon adverse health effects such as fatigue, insomnia and decreased sleep quality. Moreover, shift work has deleterious effects on both work productivity and safety. In this review, we present a brief overview of the current literature on the consequences of shift work, especially focusing on attention-associated cognitive decline and related behavioral changes. We searched two electronic databases, PubMed and RISS, using key search terms related to cognitive domains, deleterious effects, and shift work. Twenty studies were eligible for the final review. The consequences of shift work can be classified into the following three categories extracted from the literature review : 1) work accidents ; 2) commuting accidents such as car accidents that occur on the way to and from work ; and 3) attendance management at work (i.e., absenteeism, tardiness, and unscheduled early departure). These cognitive and behavioral consequences of shift work were also found to be associated with sleep disorders in shift workers. Thus, improvements in the shift work system are necessary in order to enhance workers' health conditions, work productivity, and safety.

연안역에서의 취송류의 3차원 확산특성

마현호(Hyun-Ho Ma),김창제(Chang-Je Kim) 한국해양대학교 해사산업연구소 2000 海事産業硏究所論文集 Vol.10 No.-

연안부근의 흐름을 지배하는 요인으로서는 조석에 의한 조류와 바람에 의한 취송류로 크게 분류할 수 있다. 조석 등과 같이 주기가 긴 장파에 의한 연안해역에서의 흐름은, 연안해역의 수평스케일이 연직스케일에 비해 상당히 크기 때문에 연직방향으로 수심 평균한 평면 2차원 흐름으로 평가한다. 그러나, 취송류의 경우, 수심방향의 유속분포는 수면에서 최대이며 수심이 깊어짐에 따라 대수적으로 감소(加藤始 等, 1976; Bains, etal., 1965)하며, 풍속, 풍향, 수심, 지형, 바람의 지속시간 둥 그 기구가 복잡하여 연안과 같이 수심과 지형이 크게 변하는 곳에서는 기존의 방법으로 오염물질 확산거리를 해석하면 현상을 과소평가할 가능성이 있으며, 확산방향도 연안해역의 지형적 복잡성 때문에 잘못 평가할 가능성이 있다. 특히 기름과 같은 부유성 오염물질의 이동을 해석하는 경우, 수심방향으로 평균한 평면 2차원흐름으로 해석하면 현상을 과소평가할 가능성이 있다. 이에 본 연구에서는 취송류를 지배하는 풍속, 풍향, 수심, 지형 등을 고려하여 연안해역에 적용할 수 있는 취송류의 3차원 모델을 제시하였다. The analysis of the movement of tidal current has been carried out with an assumption that tidal current is to be a 2-D plane flow in the averaged depth. Insofar as wind-induced flows, however, 3-D analysis has to be applied since wind-induced flows shows the characteristics of logarithmic velocity profile from the water surface to the bottom. The Vertical distribution of wind-induced flows mostly depends upon the vertical eddy viscosity. For this reason, Ekman's calculation does not have inertia and horizontal viscosity terms. This method of calculation has formed a basis in the study of this field. Application of this model to a region where changes of water depth and geographical features are not prominent does not hinder a higher accuracy. However, a problem of a certain degree may arise if we apply this model to a region where the changes of water depth and geography are prominent such as nearshore zones, for the inertia and horizontal viscosity terms in equation of motion are not included in the Ekman's model. Therefore, this study has aimed at quantifying the equation of motion with particular attention to the inertia and horizontal viscosity terms in question and, further, proposing a 3-D model which is capable of being applied to nearshore zones. In order to verify the 3-D characteristics of wind-induced flows due to geographical changes, a model test was performed in the wind flume, as shown in Fig. 4. and Fig. 5. The applicability of the proposed model to the Port of Ulsan was confirmed with the following results: 1. The experiment gives good results in comparison with the numerical analysis, when a structure is placed. The surface flow over the boundary of the structure is found an inverse flow against the surface. Therefore, the proposed model can be used even in the region where a structure is placed or changes of geographical changes are prominent. 2. When the proposed model was applied to the Port of Ulsan where the gradient of water depth was relatively high, it was found that the Vertical distribution of the flow exhibits the characteristics of an inverse flow.

Development of Quantitative Method for the Elements in Individual Micro Droplet

Chang-Jin Ma,Sung-Boo Choi,Ki-Hyun Kim,Chang-Hee Kang,Gong-Unn Kang,Kum-Chan Choi,Kyung-Chul Hwang 한국대기환경학회 2010 한국대기환경학회 학술대회논문집 Vol.2010 No.5월

Theoretical Calculation of Ionic Mass Resolved in Each Size of Raindrop

Chang-Jin Ma,Sung-Boo Choi,Chang-Hee Kang,Gong-Unn Kang,Kum-Chan Choi,Ki-Hyun Kim 한국대기환경학회 2009 한국대기환경학회 학술대회논문집 Vol.2009 No.10월

Hyperuricemia is a risk factor for the progression to end-stage renal disease in minimal change disease

( Su Hyun Song ),( Tae Ryom Oh ),( Hong Sang Choi ),( Chang Seong Kim ),( Dong Ryeol Ryu ),( Sung Gyun Kim ),( Sun-hee Park ),( Seong Kwon Ma ),( Soo Wan Kim ),( Eun Hui Bae ) 대한신장학회 2021 Kidney Research and Clinical Practice Vol.40 No.3

Background: Minimal change disease (MCD) is one of the most common causes of nephrotic syndrome worldwide. Hyperuricemia increases the end-stage renal disease (ESRD) risk in glomerulonephritis. In this study, we aimed to determine the effect of high serum uric acid levels on the progression to ESRD in MCD. Methods: A total of 800 patients diagnosed with MCD by kidney biopsy were retrospectively analyzed. We determined the relation-ship of hyperuricemia with the progression to ESRD in MCD using the Cox proportional hazard model and Kaplan-Meier survival anal-ysis. The primary outcome was defined as the initiation of dialysis or kidney transplantation. Results: A total of 42 patients (5.3%) progressed to ESRD during the follow-up period. In the restricted cubic spline curve, serum uric acid levels exhibited a positive correlation with ESRD progression in patients with MCD. In the fully adjusted model, the risk of MCD progression increased by 29% for every 1 mg/dL increase in the baseline serum uric acid level (hazard ratio [HR], 1.29; 95% confi-dence interval [CI], 1.09-1.54; p = 0.004). Falling into the high uric acid group (serum uric acid level > 7 mg/dL in men and > 6 mg/ dL in women) was also a risk factor for progression of MCD to ESRD (HR, 3.40; 95% CI, 1.59-7.31; p < 0.001). Conclusion: Our study shows that hyperuricemia is an independent risk factor for the progression to ESRD in patients with MCD.

감잎의 광노화 피부 개선에 미치는 효과(1)

이창현(Chang Hyun Lee),김남석(Nam Seok Kim),최동성(Dong Seong Choi),오미진(Mi Jin Oh),마상용(Sang Yong Ma),김명순(Myoung Soon Kim),유승정(Seung Jeong Ryu),권진(Jin Kwon),신현종(Hyun Jong Shin),오찬호(Chan Ho Oh) 한의병리학회 2013 동의생리병리학회지 Vol.27 No.6