AN IN-SITU YOUNG'S MODULUS MEASUREMENT TECHNIQUE FOR NUCLEAR POWER PLANTS USING TIME-FREQUENCY ANALYSIS

Choi, Young-Chul,Yoon, Doo-Byung,Park, Jin-Ho,Kwon, Hyun-Sang Korean Nuclear Society 2009 Nuclear Engineering and Technology Vol.41 No.3

Elastic wave is one of the most useful tools for non-destructive tests in nuclear power plants. Since the elastic properties are indispensable for analyzing the behaviors of elastic waves, they should be predetermined within an acceptable accuracy. Nuclear power plants are exposed to harsh environmental conditions and hence the structures are degraded. It means that the Young's modulus becomes unreliable and in-situ measurement of Young's modulus is required from an engineering point of view. Young's modulus is estimated from the group velocity of propagating waves. Because the flexural wave of a plate is inherently dispersive, the group velocity is not clearly evaluated in temporal signal analysis. In order to overcome such ambiguity in estimation of group velocity, Wigner-Ville distribution as the time-frequency analysis technique was proposed and utilized. To verify the proposed method, experiments for steel and acryl plates were performed with accelerometers. The results show good estimation of the Young's modulus of two plates.

GASKET LIFE CRITERIA AT LOW TEMPERATURES ADOPTING PROPORTIONAL COMPENSATION FOR LOSS OF FLEXIBILITY AND CONFORMABILITY

Young-Doo Kwon,Seong-Hwa Jun,Jin-Sik Han,Dong-Jin Lee 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.1

In the automobile industry, the service life of gaskets is defined as the time until which a released gasket recovers 60 % of the original compression. It was observed that the recovery curves of gaskets were highly nonlinear at high temperatures, and relatively nonlinear at temperatures above the room temperature. However, it was also noted that the recovery curves of the gaskets at temperatures below room temperature exhibited linearity with respect to the ln(time). Automotive manufacturers demand gasket life criteria that exceed a specific time or the entire life of a car. In the case of gaskets used at lower temperatures, since materials encounter losses in its flexibility and conformability, the definition of service life specifying a 60 % recovery may not be sufficiently safe to eliminate possible leakages. In this study, new gasket life criteria that could be used at low temperatures were proposed. The new criteria were proposed based on the change in Young’s modulus of the gasket material in order to conserve the sealing capability.

소규모 하수처리를 위한 파일럿 규모 이중슬러지 KNR^® (Kwon's nutrient removal) 시스템의 영얌염류 제거성능 평가

안진영,권중천,김윤학,정유훈,김두언,유선호,김병우,An, Jin-Young,Kwon, Joong-Chun,Kim, Yun-Hak,Jeng, Yoo-Hoon,Kim, Doo-Eon,Ryu, Sun-Ho,Kim, Byung-Woo 한국청정기술학회 2006 청정기술 Vol.12 No.2

본 연구에서 소규모 하수고도처리를 위한 이중슬러지(Dual sludge) $KNR^{(R)}$ (Kwon's nutrient removal) 시스템이 개발되었다. $KNR^{(R)}$ 시스템은 부유성장식 탈질미생물과 부착성장식 질산화미생물을 분리시킨 이중슬러지 공정으로 최초침전조, 혐기조, 무산소조, 농축조의 복합기능을 수행하는 UMBR (Upflow multi-layer bioreactor)과 펠렛형 담체가 충진된 호기성 담체조로 구성되어 있다. 소규모 하수처리시 본 개발공정의 안정성과 처리성능을 평가하기 위해 처리용량 $50m^3/d$ 규모의 파일럿 플랜트를 고도처리 공정으로 개선공사 중인 처리용량 $50m^3/d$ 규모의 실제 소규모 마을하수처리장에 적용하였다. UMBR과 담체조의 체류시간은 각각 4.7 h와 7.2h이었으며, 반응조 수온은 $18.1{\sim}28.1^{\circ}C$이었다. 유입 하수량과 유입수의 BOD/N의 변동폭이 컸음에도 불구하고 파일럿 플랜트는 안정된 처리성능을 보였다. 전체 실험기간 중 처리수의 $COD_{cr}$, $COD_{Mn}$, $BOD_5$, TN, TP의 평균 농도는 11.0 mg/L, 8.8 mg/L, 4.2 mg/L, 3.5 mg/L, 9.8 mg/L, 0.87/0.17 mg/L (poly aluminium chloride(PAC) 투입/미투입)이었으며, 제거율을 각각 95.3%, 87.6%, 96.3%, 96.5%, 68.2%, 55.4/90.3% 이었다. 잉여슬러지 발생량은 $A_2O$와 Bardenpho 등과 같은 단일슬러지를 이용하는 고도처리공정과 비교시 약 1.9~3.8배 낮은 $0.026kg-DS/m^3$ and 0.220 kg-DS/kg-BOD로 나타났다. A simple dual sludge process, called as $KNR^{(R)}$ (Kwon's Nutrient Removal) system, was developed for small sewage treatment. It is a hybrid system that consists of an UMBR (Upflow multi-layer bioreactor) as anaerobic and anoxic reactor with suspended denitrifier and a post aerobic biofilm reactor, filled with pellet-like media, with attached nitrifier. To evaluate the stability and performance of this system for small sewage treatment, the pilot-scale $KNR^{(R)}$ plant with a treatment capacity of $50m^3/d$ was practically applied to the actual sewage treatment plant, which was under retrofit construction during pilot plant operation, with a capacity of $50m^3/d$ in a small rural community. The HRTs of a UMBR and a post aerobic biofilm reactor were about 4.7 h and 7.2 h, respectively. The temperature in the reactor varied from $18.1^{\circ}C$ to $28.1^{\circ}C$. The pilot plant showed stable performance even though the pilot plant had been the severe fluctuation of influent flow rate and BOD/N ratio. During a whole period of this study, average concentrations of $COD_{cr}$, $COD_{Mn}$, $BOD_5$, TN, and TP in the final effluent obtained from this system were 11.0 mg/L, 8.8 mg/L, 4.2 mg/L, 3.5 mg/L, 9.8 mg/L, and 0.87/0.17 mg/L (with/without poly aluminium chloride(PAC)), which corresponded to a removal efficiency of 95.3%, 87.6%, 96.3%, 96.5%, 68.2%, and 55.4/90.3%, respectively. Excess sludge production rates were $0.026kg-DS/m^3$-sewage and 0.220 kg-DS/kg-BOD lower 1.9 to 3.8 times than those in activated sludge based system such as $A_2O$ and Bardenpho.

유한요소법을 이용한 박막이 있는 물체의 응력파해석

권영두,권혁춘,이상태,서병철 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.2

Generally, as objects impact each other, coating layer is regarded as little affecting transmission and reflection of shock wave. However, we thought that material properties and thickness of coating layer would actually affect objects. So this paper was performed by finite element analysis (FEA) for transmission and reflection of stress wave propagation at two bars having different material properties. Also, as coating layer having different material properties was inserted between bars, we looked into the behavior of stress wave propagation and compared the result of FEA and theoretical result. As using them, FEA for actual piezo electric ceramic was performed. The damaged cause of piezo electric ceramic was confirmed by the effect of reflected wave. To decrease the effect of reflected wave, we analyzed it as changing thickness and material of coating layer and the shape of piezo electric ceramic. Afterwards, we inquired thickness and material of coating layer and the shape of piezo electric ceramic being able to minimize the effect of reflected wave. (Receivad September 30 2004)

制御壓延後 冷却速度가 高張力鋼의 機械的 性質에 미치는 影響에 관한 硏究

權永斗,李相允 東亞大學校 大學院 1986 大學院論文集 Vol.11 No.-

This study reports the changes in structural and mechanical properties of high tensile strength steel treated by the controlled rolling and interrupted cooling technique, a newly developed controlled rolling process, as compared to the conventional controlled rolling technique. The results obtained from this experiment are summarized as follows: 1) Optical micrographs have revealed that the microstructures of specimens treated by the CR2 technique have much finer ferrite and bainite and pearlitic structure, in paticular, forms not only finely but more uniformly, as compared to the CR1 technique. 2) The grain size measurements have shown that the grain size of specimens control-rolled by CR2 with a more rapid cooling rate of interrupted cooling is finer than in the case of CR1. 3) The values of hardness obtained from the CR2 technique have been found to be considerably increased compared to those for a given specimen, hardness in creasing with increasing the carbon content. 4) Tensile property analyisis has indicated that yield stregth increases as the carbon content of specimens increase, resulting in higher increase in yield stress for the CR2 that for the CR1 technique. 5) Impact tests have revealed that the transition temeperatures determined for specimens control-rolled by the CR2 are lower than those for specimens control-rolled by the conventional methosd CRq, showing a consderable amount of improvement of toughness for specimens related to the CR2 technique consequently, the interrupted cooling technique after controlled rolling process can provide high tensile strength steels with mechanical properties superior to those obtainable from the conventional controlled rolling technique.

빈뇨-불안 증후군의 임상적 특성

김두홍,권헌영 大韓泌尿器科學會 2001 Korean Journal of Urology Vol.42 No.8

초기응력이 있는 일단고정 Plate Strip의 선형 및 비선형해석

權永斗,徐昌敏 경북대학교 공과대학 1987 工大硏究誌 Vol.16 No.-

The set of finite element equations of motion of an initially stressed elastic solid is derived by using the principle of virtual displacement. And this is compared with what obtained from Hamilton's principle. The set of equations of motion is applied to an initially stressed fixed-free plate strip on the sudden lateral loading condition at the free end. By comparing numerical result, we shall examine the effect of incremental stresses, and the selective reduction of the order of Gauss-Legendre quadrature.

LQ서보제어기를 이용한 천정크레인 시스템의 위치 제어

조영호,이한석,신승권,안두수 成均館大學校 科學技術硏究所 1998 論文集 Vol.49 No.1

An overhead crane is commonly used in factories and dockyards. An overhead crane operation is manually accomplished by skilled operators. Usually, the skill of the operators is relied on to bring the load to its destination exactly and have it stationary at the end of the journey. Recently, the concept of automation is widely introduced in shipping and unloading operation using the overhead crane for the enhanced producity. In this paper, we reduced overhead cranes scale and objection for experimental purpose in lab. The controller for an overhead crane was designed using LQ-servo technicques and simulated by MATLAB. The performance of the controller was verified through the experiment results and the simulation walls by MATLAB.

국립공원 계룡산 이용자의 행태와 만족도에 관한 연구

오두영,이권구 公州大學校 資源科學硏究所 1996 資源科學硏究論文集 Vol.4 No.-

The purpose of this theses is to examine the function of the National Park as a recreation place and the degree of visitors' satisfaction at the environment including the facilities in National Park by analyzing the important factors having an effect on them, and to show the plan for developing and managing the National Park. In the course of this study, the area of survey was selected Mt. Kyeryong National Parks Kongju shi Chung Chong Nam Do. The main method of data collection was interviews and questions and to collect data, a total of respondents was 322, sampled as final subjects of survey. The number of question in the questionnaire summed to 58, including 23 general questions and 35question on evalution after visiting park. The independent variables were divided into two;individual attributes(sex, age, job, schcooling, etc. 4questions) and a conductive variables (frequency of visiting,way of transport, from of company, length of in park, etc. 19 questions0 and the dependent variables were the satisfaction of landscape, the road and the facilities and inclusive satisfaction. The cronbach's alphas program was used to measure the reliability of Likert Scales. The cronbach;coefficient alphas all the categories of competences were 0.91. The analysis of data was used SPSS PC+ statistical analysis program in IBM 486 computer and was applicate such as a statistical methods. Also, a statistical level of sampling connective factor was frequency. T-test, multiple-regression analysis with a 01 significance level. The result od this study were as follows; 1.As for the respondents' individual attributes, the sex of respondents was mainly female, their age was mainly twenties, their schooling was mainly higher than that of secondary school graduates, their job was mainly student and housewife. 2.As for the respondents conduct a place of residence was mainly Tae-Jeon (69.9%), the means of transportation was mainly taking a regular bus (51.6%), a form of company was mainly friend or lover (49.4%), a visiting season was autumn(51.9%), and method of solving meal was to uss restaurants(48.4%). As for the number of using park for a year, visiting at any time were in large numbers(31.1%), but judging from the time staying in park (less than five hours user (59.6%) one day user(26.1%)), we could know that it was one day visiting type. 3.As for the feature of user's visiting purpose, the male was likery to take a walk or to climb, the female was likely to take a rest, to look at the sight and to date. As for the age, those more than forties were to sihtseeing tour, thirties∼forties were to take a walk or to climb, twenties∼thirties who want to date with friend or lover were mainly in large numbers. According to the job, anong the visiting purpose, those who has the purpose of taking a walk or climbing were office worker, service worker, student. Those who take the purpose of looking at the sight, going on a picnic with one's family were housewives, those who has the purpose of dating were mainly students. Compared with one's schooling, regardless of schooling, taking a walk, climbing and sightseeing are comparatively in large numbers, and most of students were for dating with their friends or lovers. 4.The primary factors that had on effect on satisfaction after using the natyre are the beauty of nature, mountain, valley, the harmony of tree, and change of season. But a variety of tree and a feature of sight present a less satisfaction, compared with others factor. 5.The primary factors that decide the satisfaction of using the road are a system of guidence, the width of road and paking materials. And according to being or not being the guidance at the place where many peole visit, it was mainly affected. And an ill-matched packing with natyre (pavement, concrete, block of a footpath) was not good. 6.The primary factors of satisfaction of using the feature were mainly the location and number of waste basket and dumping ground, the number of convenient facilities. Especially a confusion of use has an great effect on it. 7.The primary factors of satisfaction of aim of visiting park are mainly taking a walk, climbing, sightseeing, and dating. But compared with other factor, both viewing cultural inheritance and observation natyre pressent low satisfaction.

MAO모델을 사용한 관계 데이타베이스의 논리적 설계방법론

조동영,백두권,황종선 한국경영과학회 1991 韓國經營科學會誌 Vol.16 No.2

In this paper, we present a stepwise design methodology for relational databases using a new conceptual data model, the MAO(Multiple Aspects-based Object.) model. Our methodology consists two steps: first, data requirements are conceptualized the MAO model form in the relational model supported by transformation DBMSs. A top-down approach is used for the MAO modeling in the first step, and more accurate database design of real world than other methodologies supports easier and more database design of real world than other methodologies using existing data models.