대형 Flange bolt의 냉간단조 성형공법 적용에 관한 연구

이권수,안용식 한국금형공학회 2024 한국금형공학회지 Vol.18 No.1

Due to increasing demands for environmental protection and cost reduction, the application of cold forging technology in the production of large-sized flange bolts, which was mainly manufactured through hot forging, has become necessary. An investigation was conducted on the die design of preform dies for cold forging a large-sized flange bolt. The die design, which utilized the upsetting process, was determined insufficient due to the excessive principal stress exerted on the die. Nevertheless, the die design utilized in the trimming process showed its compatibility with the cold forging of the flange bolt. The die design was evaluated using the Finite Element Method (FEM) to identify the most optimal state in terms of the preform die's outer diameter. As a result, the results of the study have been applied to the actual manufacturing process, leading to the creation of a forging die with an extended lifespan.

이중동심관내의 선회 및 비선회유동의 특성 비교 연구

李權洙 진주여자전문대학 1997 論文集 Vol.20 No.-

An exprimental investigation of characteristics between swirl flow and non-swirl flow for Re=40,000 in an axisymetric annular pipe. The axial velocity profiles with swirl flow are showing nearly same value at the inside of wall at the same swirl intensity, and the static pressures are much effected by swirl flow then that of non-swirl flow, almost 20 times higher at the inlet of the test tube.

직경비 0.3인 수평이중동심관내의 무차원 속도 분포

이권수 진주여자전문대학 1996 論文集 Vol.19 No.-

For horizontal concentric annular tubes with diameter ratio 0.3 and with Reynolds numbers from 40,000 to 80,000. non-dimentional velocity distributions for each Reynolds numbers are presented and these are also compared with the case of turbulent fluid flow in a single tube. These experimental results can use the basis of the experiments for turbulent swirled flow characteristics in a horizontal concentric annuli.

자동차 휠 너트용 냉간단조 금형에서 인서트링과보강링의 최적 설계에 관한 연구

이권수,김기엽,안용식 한국소성∙가공학회 2018 소성가공 : 한국소성가공학회지 Vol.27 No.3

In order to increase the lifetimes of cold forging dies, insert rings are generally used. In this study, an insert ring and shrunk ring of the flange upsetting die were designed for the cold forging of an automotive wheel nut. The Stress distribution occurring in the die during forging was simulated using a commercial finite element analyzing program. The effects of the fitting interference and inclined angle of the insert ring on the compressive stress of the die inside were also investigated. The simulated data were compared with the real lifetimes of the forging dies. The maximum compressive stress acting on the edge of a forging die should have the most influence on die lifetime, an idea which could help develop the die design with the longest lifetime. The design of the most optimal forging die with the longest lifetime is made possible by analyzing the maximum inner pressure and principal stress between the shrunk ring and insert ring.

상대 관측 정보 신뢰도 판단을 통한 다중자율무인잠수정의 정밀한 위치 추정

이권수,최기환,이필엽,김호성,이한솔,강형주,이지홍 제어·로봇·시스템학회 2022 제어·로봇·시스템학회 논문지 Vol.28 No.6

This paper describes a reliability assessment of relative observations for multiple autonomous underwater vehicles (multiple-AUVs). Swarm control and collision avoidance, the primary issues of a multiple-AUV system, intrinsically need precise localization of Multiple-AUVs, and relative observations of each autonomous underwater vehicle (AUV) are critical to improving localization precision. However, because relative observations are usually measured by ultrasonic sensors, the reliability of sensor data varies depending on the characteristics of each AUVs’ trajectories, as implied in previous our study. Therefore, this paper proposed a reliability assessment method based on the trajectories of each AUV and integrated the derived reliability of relative observations into the multiple-AUV localization algorithm. Consequently, localization performance with real sea experimental data is improved up to 77.4% compared with the previous independent navigation algorithm of each AUV and 60.6% compared with the previous study without the reliability assessment. We conclude that the proposed method is suitable for precise localization through relative observations. .

Does uroflowmetry parameter facilitate discrimination between detrusor underactivity and bladder outlet obstruction?

이권수,송필현,고영휘 대한비뇨의학회 2016 Investigative and Clinical Urology Vol.57 No.6

Purpose: Though urodynamic study (UDS) is the current established standard to distinguish between detrusor underactivity (DU) and bladder outlet obstruction (BOO), concerns of patient discomfort and potential complications of catheterization deters its use. We inspected clinical variables to discriminate between DU and BOO in uroflowmetry, which can be more easily performed in clinical practice. Materials and Methods: Total 240 men who both underwent UDS and uroflowmetry were reviewed. The patients were divided into 2 groups by a single experienced urologist based on UDS outcome; DU (n=111) and BOO (n=129). From uroflowmetry, 5 variables including maximal flow rate (Qmax), average flow rate (Qave), voiding volume (VV), postvoid residual urine (PVR), and value of Qmax minus Qave (DeltaQ) was obtained. Multivariable analysis including receiver operating characteristic (ROC) curve analysis was performed to identify the important diagnostic predictors. Results: The mean age (±standard deviation) was 65.3±9.2 years. Except Qave, all uroflowmetry components were significantly different between DU and BOO groups. DeltaQ was smaller in DU group (8.71 mL/s vs. 5.26 mL/s, p<0.001). By logistic regression analysis, DeltaQ (Exp(B)=0.648, p<0.001) and PVR (Exp(B)=1.009, p<0.001) significantly discriminate DU and BOO diagnosis. In diagnosing DU using a single variable, the area under the curve of ROC from DeltaQ (0.806) was significantly higher than that from Qmax (0.763, p=0.0126) and Qave (0.574, p<0.0001). Conclusions: Our findings suggest that DeltaQ is a novel predictor capable of discriminating DU from BOO in men with obstructive lower urinary tract symptom.

VOC 및 악취제거를 위한 Biofilter 기술

이권수 한밭대학교 에너지청정기술연구소 2002 에너지청정기술논문집 Vol.2 No.1

Nano silica를 이용한 고강도 액상실리콘의 제조 및 그 특성

이권수,강두환,여학규 한국공업화학회 2002 한국공업화학회 연구논문 초록집 Vol.2002 No.0

실리콘 고무는 내열성, 내후성 및 전기특성이 우수하여 응용분야가 점점 넓어지고 있으나 기계적 강도가 약하여 고강도를 요하는 부분에서는 사용에 어려움을 겪고 있다. 이를 개선하기 위하여 silane coupling agent와 nano silica를 이용한 고강도 액상실리콘을 제조하였다. THAH를 촉매로 하여 octamethylcyclotetrasiloxane을 평형중합시켜 양 말단에 vinyl기가도입된 polyorganosiloxane prepolymer를 제조하였으며 여기에 nano silica의 함량을 10, 20, 30 및 40 phr 및silane coupling agent를 투입하여 우수한 기계적 강도를 갖는 액상실리콘을 제조하였다. 제조한 prepolymer의 구조를 FT-IR과 NMR을 이용하여 확인하였으며 액상실리콘을 120℃에서 10분간 가교시킨 후 UTM을 이용하여 인장강도, 신장율 및 인열강도를 측정하였으며 전기적 특성으로는 체적저항 및 절연파괴강도를 측정하였다.

Role of urine osmolality as a predictor of the effectiveness of combined imipramine and desmopressin in the treatment of monosymptomatic nocturnal enuresis

이권수,장준보,장재윤,고영휘,박용훈,송필현 영남대학교 의과대학 2015 Yeungnam University Journal of Medicine Vol.32 No.2

Background: We examined the usefulness of urine osmolality, as a predictive factor in the treatment of monosymptomatic nocturnal enuresis (NE) with combination therapy of imipramine and desmopressin. Methods: From May 2014 to April 2015, 59 monosymptomatic NE patients participated in this study. Early morning urine osmolality was measured at 1 week and 1 day before combination therapy of imipramine and desmopressin, and at 1 week and 2 weeks after therapy. The response to combination therapy was evaluated at 3 months after treatment. The mean period of combination therapy was 6.4± 4.2 weeks. Therapeutic response was classified as complete (0-1 wet night/week), partial (over 50% reduction of night) and non-responders (less than 50% reduction of night). Results: The cumulative rate of the complete and partial responders was 76.3%. Among the 3 groups, the statistically lowest value of pre-treatment urine osmolality was observed in the complete responder group (p<0.001). Urine osmolality increased in all groups after treatment, however, statistically the greatest difference between pre and post-treatment urine osmolality was observed in the complete responder group (p=0.024). No serious side effects were observed. Conclusion: Early morning urine osmolality and change of urine osmolality between pre and post-treatment have predictive values in the response to combined imipramine and desmopressin for treatment of monosymptomatic NE.

문화체육관광 빅데이터 플랫폼 구축 방안 및 데이터 활용전략 -문화정보원 사례를 중심으로-

이권수 한국지역정보화학회 2019 한국지역정보화학회 학술발표대회 논문집 Vol.2019 No.10