인체 무게 중심 분할에 따른 500m 숏트트랙 스피드 스케이팅 출발 기술 분석

백진호,정남주,한기훈,이용구,윤동섭,이용식,Back, Jin-Ho,Chung, Nam-Ju,Han, Ki-Hoon,Lee, Yong-Goo,Yoon, Dong-Seob,Lee, Yong-Sik 한국운동역학회 2003 한국운동역학회지 Vol.13 No.3

The purpose of this study was to attempt new starting motion and supply present starting motion in the 500M short track speed skating according to the center of gravity position. The center of gravity position ratio was divided starting motion into five(type A : front 80%-back 20%, type B front 70%-back 30%, type C : front 50%-back 50%, type D : front 30%-back 70%, type E : front 20%-back 80%). The three dimension motion analysis with DLT(direct linear transformation) method was executed using two video cameras. The following conclusion was that It was appear that reaction and execution time in starting motion was the most short in type B. It was characteristic that step of skaters was shorten and center of gravity position ratio was not effect to change of the step in each event. It was appear that the displacement of type D and type E were longer than that type A and type B during the starting motion. It was appear that skill types of center of gravity position ratio to the front were lower than that to the back and contract a posture. Observing the above, it was conclusion that skill type B of center of gravity position ratio to the tent was more effect than that to the back. But it is important that these skill type was most used to the competition and estimate the result.

薄板 spring back에 관한 硏究

白南柱,金南植 부산대학교 공과대학 1981 硏究報告 Vol.22 No.-

薄板의 塑性굽힘 加工에서, 스프링 백은 아주 複雜하고 어려운 問題로 잘 알려져 있다. 本 論文에서는 스프링 백을 plane stress와 plane strain 理論으로 區分하여 解析하고 V型 다이와 펀치로서 굽힘 實驗을 하여 다음과 같은 結論을 얻었다. 1. 굽힘변형과정은 2種類의 形式으로 大別되며 제각기 서로 다른 스프링 백의 변형특성을 나타낸다. 2. 스프링 백은 굽힘 荷重에 影響을 받으며 그 程度는 R/t의 크기에 관계한다. 3. 理論解析에서 얻어진 結果와 實驗은 잘 일치한다. In this plastic bending of sheet Metals, spring back is a well-known phenomenon as a very complex and different problem. In this report, the author deals with experimentally the process of deformation in the plastic bending of sheet metals with the V-die and punch and effects of various factors on the spring back in the matter mentioned above. The results obtained as follows: ⅰ) the process of deformation in bending was divided into two main types, each of which had the respective change of spring back. ⅱ) Spring back was mainly influenced by bending load, but the degree of its influence was depended on the ratio of the radius R at the extreme point of punch to the thickness t of sheet metals. ⅲ) the results obtained in the theoretical analysis are well agreed with the experiments.

대학 골프 선수의 Pitching wedge 스윙동작의 운동학적 특성 분석

백진호,윤동섭,김재필,Back, Jin-Ho,Yoon, Dong-Seob,Kim, Jae-Phil 한국운동역학회 2003 한국운동역학회지 Vol.13 No.3

The purposes of present study were to determine the major check-points of golf swing from the review of previous studies, and to suggest additional information on the teaching theory of golf. The golf swing motion of 6 male and female elite university golf players were filmed with 16mm Locam II high speed cameras at the speed of 200f/s, and variables such as time, displacement, angle, velocity were calculated and analyzed by 3D Cinematography using DLT method. The results were: 1. Differences were shown in the ratio of weight distribution on the feet, cocking angle, take-back velocity, club-head velocity at impact depending upon the physical characteristics and club used for swing. 2. Time for the down-swing and impact were $0.27{\sim}0.29s$ in men and $0.29{\sim}0.32s$ in women, which was 1/3 of the time for the back-swing. Women showed longer total swing time than men because of longer time in back-swing, follow-through and finish. 3. Men showed larger range of motion in shoulder and knee joints than women, on the other hand women showed larger range of motion in hip joint than men. 4. Cocking motion and right elbow flexion were occurred at the top of back-swing and cocking release was occurred at the moment of impact. Maximum rotations of shoulder and hip joints were found between the top of back-swing and down-swing phase. 5. Women showed lower back-swing velocity than men, and men showed higher club velocity(men: $38.2{\sim}38.6m/s$, women: $35.1{\sim}36.4m/s$) than women.

Application of sigmoidal optimization to reconstruct nuclear medicine image: Comparison with filtered back projection and iterative reconstruction method

Shin, Han-Back,Kim, Moo-Sub,Law, Martin,Djeng, Shih-Kien,Choi, Min-Geon,Choi, Byung Wook,Kang, Sungmin,Kim, Dong-Wook,Suh, Tae Suk,Yoon, Do-Kun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.1

High levels for noise and a loss of true signal make the quantitative interpretation of nuclear medicine (NM) images difficult. An application of profile optimization using a sigmoidal function in this study was used to acquire the NM images with high quality. And the images were acquired by using three kinds of reconstruction method using each same sinogram: a standard filtered back-projection (FBP), an iterative reconstruction (IR) technique, and the sigmoidal function profile optimization (SFPO). Comparison of image according to reconstruction method was performed to show a superiority of the SFPO for imaging. The images reconstructed by using the SFPO showed an average of 1.49 times and of 1.17 times better in contrast than the results obtained using the standard FBP and the IR technique, respectively. Higher signal to noise ratios were obtained as an average of 12.30 times and of 3.77 times than results obtained using the standard FBP and the IR technique, respectively. This study confirms that reconstruction with SFPO (vs FBP and vs IR) can lead to better lesion detectability and characterization with noise reduction. It can be developed for future reconstruction technique for the NM imaging.

디지털 생산성 향상을 위한 신경망 사용자 인증 모형 연구

하태용,신용백 한국생산성학회 2004 生産性論集 Vol.18 No.3

Web security middle ware system has two functions, which are user authentication and security access control. User authentication is to verify a valid user. User authentication is commonly based on the method of password. The losing, opening, and hacking password causes a critical security problem. This research is focused on developing a neural network approach for user authentication using keystroke. Two-phase approach for user authentication and verification is designed. This first-phase is based on pattern analysis of keystroke of user ID and password. The second-phase also employs patterns analysis on keystroke of randomly generated characters complementarily. Keystroke includes the information on duration of pressing a character and delay interval time between pressing a character and next character. The proposed approach basically relied on the individual keystroke pattern. Conventional back-propagation learning algorithm is adopted with multi-modal sigmoid function. Various experimental analysis are performed to verify the presented method. Seven characters are used as keystroke pattern data. Classical minimum distance classifier and single perceptron are compared to back-propagation. Back-propagation algorithm has superior performance among the three approaches having 0.02441 FRR and 0.0288% FAR, which are close to other recognition rate. After user authentication is performed, Access control is designed for controlling not permitted or not allowed access. The presented neural network based user authentication is applied for Web security middle ware system.

신경회로망을 이용한 용접잔류응력 예측 및 최적의 용접조건 선정에 관한 연구

차용훈,김하식,이연신,김덕중,성백섭 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1

The objective of the study is the development of the system for effective prediction of residual stresses using the back propagation algorithm from the neural network. The achieve of this goal, the series experiment were carried out and measured the residual stresses using sectional method. Using the experimental results, the optional control algorithms using a neural network should be developed in order to reduce than the effect of the external distribution during GMA welding processes. Also, comparison with the measured and the calculated results from the FEM(finite element method) and verification of the developed system was carried out. This system can not only help to understand the interaction between the process parameters and residual stress, but also, improve the quantity control for welded structures. Then the results obtained from this study are as follows. Through comparison between the measured and calculated results, the neural network based on back propagation algorithm is the best techniques to predict the process parameter. A new techniques which predict the process parameter such as welding voltage, arc current, welding speed using the training the raw dates, will be proposed.

Pd^(1) Location and Adsorbate Interactions in PdH-SAPO-34 studied by EPR and Electron Spin-Echo Modulation Spectroscopies

Back, Gern-Ho,Yu, Jong-Sung,Vadim Kurshev,Larry Kevan 國立 昌原大學校 基礎科學硏究所 1994 基礎科學硏究所論文集 Vol.6 No.-

EPR and electron spin-echo modulation (ESEM) spectroscopies have been used to monitor the location of Pd_(II) and its interaction with water, methanol, ethanol, ethene, benzene, carbon monoxide and ammonia in silicoaluminophosiphate type 34 (SAPO-34) molecular sieve containing Pd(II) by ion exchange. After activation at 600℃, three different Pd' species are observed: A_(1)(g_(⊥) = 2.177), A_(2)(g_(⊥) = 2.136) and A_(3)(g_(⊥) = 2.070) with a common g_(Ⅱ)= 2.92. These correspond to three different site locations in the framework. A_(1) is assigned to the least accessible site Ⅲ in the centre of a hexagonal prism, A_(3) to site I displaced from a six-ring into the ellipsoidal cage and A_(2) to the most accessible site Ⅳ near an eight-ring window based on adsorption of oxygen and hydrogen and ^(31)P modulations from the SAPO framework observed by ESEM. Oxygen and water oxidize Pd_(I) lons in an activated sample to Pd^(Ⅱ) ions complexed to O_(2)^(-), indicating water decomposition. Adsorption of methanol and ethanol causes a change in the EPR spectrum which indicates some relocation of Pd^(Ⅰ) to allow better coordination with one molecule of the alcohol. Exposure to ethene also changes the EPR spectrum, indicating interaction of Pd^(Ⅰ) with it. ESEM shows that the Pd^(Ⅰ) species coordinates to one ethene molecule. The adsorption of carbon monoxide results in a Pd^(Ⅰ) complex with three molecules of carbon monoxide based on resolved ^(13)C superhyperfine splittings. Upon adsorption of ammonia, one molecule of ammonia coordinates to Pd^(Ⅰ) based on resolved nitrogen hyperfine coupling.

Permeability Effects of the Ceramic Candle Filter on Back-Pulse Cleaning System

Young Ryoul Back,Dong Kyu Chung,Hyun Il Jeong,Soo Choon Kang,Myung S. Jhon 대한기계학회 1997 KSME International Journal Vol.11 No.3

역전파 신경회로망을 이용한 가공조건에 따른 STD-11 절단면의 신뢰성 평가

김선진,성백섭,조규재,김하식,반제삼 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.5

The purpose of this study was to present the method to choose the optimum machining condition for the wire EDM. This was completed by examining the ever-changing quality of the material and by improving the function of the wire electric discharge machine. Precision metal mold products and the unmanned wire electric discharge machining system were used and then applied in industrial fields. This experiment uses the wire electric discharge machine with brass wire electrode of 0.25mm. To measure the precision of the machining surface, average values are obtained from 3 samples of measures of center-line average roughness by using a third dimension gauge and a stylus surface roughness gauge.

신경회로망을 이용한 가공조건에 따른 원형가공 표면거칠기 평가

성백섭,김일수,차용훈 한국산업안전학회 2002 한국안전학회지 Vol.17 No.1

The purpose of this study was to present the method to choose the optimization machining condition for the wire electric machine. This was completed by examining the ever-changing quality of the material and by improving the function of the wire electric discharge machine. Precision metal mold products and the unmanned wire electric discharge machining system were used and then applied in industrial fields. This experiment uses the wire electric discharge machine with brass wire electrode of 0.25mm. To measure the precision of the machining surface, average values are obtained from 3 samples of measures of center-line average roughness by using a third dimension gauge and a stylus surface roughness gauge. In this experiment, we changed no-node voltage to 7 and 9, pulse-on-time to 6㎲, 8㎲ and 10㎲, pulse-off-time to 8㎲, 10㎲ and 13㎲, and experimented on wire tension at room temperature by 1000gf, 1200gf and 1400gf, respectively.