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.

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.

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

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)

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.

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.

천정 크레인 시스템의 위치제어와 진동저감에 관한 연구

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

Overhead crane systems are widely used for material transportation in many industrial fields. However, undesired swing can always be found during the moving progress, especially at the end location of the transport. The swing may increase the carrying time and cause safety problems. In order to achieve the target position, this paper used a PD controller and used a fuzzy controller to reduce swing angles found during the moving progress. The performance of controller was verified through the experimental results and the simulation results by MATLAB.

知能的 컴퓨터 補助敎育을 위한 ERIC 시스템 具現에 관한 硏究

정영식,황종선,김창화,인 호,백두권 강릉대학교동해안지역연구소 1990 東海岸硏究 Vol.1 No.2

ICAI시스템은 일반적으로 전문가 모듈, 교사 모듈, 학생모델 모듈 및 인터페이스 모듈의 4가지 構成要素로 구성된다. 本 硏究에서는 4가지 모듈중에서 전문가 모듈과 교사 모듈의 機能을 遂行하도록 하기 위한 지식베이스를 構築하였다. 먼저 必要한 지식베이스들을 分類하고 지식베이스를 構築하기 위한 接近方法들을 硏究하였다. 構築된 지식베이스는 코스웨어 자체에 修正을 가하지 않고 학습전략(learning strategy)을 다양하게 하기 위해서 Domain Knowledge와 Control Knowledge로 分離하였고 Domain Knowledge는 EA모델을 통하여 코스웨어를 構築하였으며, Control Knowledge는 規則基盤(rule-based)을 利用하여 學習進行 및 評價에 필요한 知識들을 構築하였다. 이를 基礎로 하여 ERIC시스템을 設計, 具現하였다. ICAI system consists of the four modules, i.e., expert module, tutor module, student model module and interface module. This paper shows the knowledge base construction to perform the functions of expert module and tutor module of the four modules. At first we identified the essential knowledge bases in ICAI system and researched the approach for the knowledge base construction. The constructed knowledge base was divide into the domain knowledge and the control knowledge to perform the several learning strategies without the courseware modification. The domain knowledge constructed by EA model represents the courseware contents and the rule-based control knowledge represents the information necessary to perform the learning process and student estimation. Based on these methodogies, we designed and implemented ERIC system.

MAO모델을 사용한 관계 데이타베이스의 논리적 설계방법론

조동영,백두권,황종선 한국경영과학회 1991 한국경영과학회지 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.