• Title/Summary/Keyword: Model Requirements

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Prediction of Structural Performance of an Automotive Ball Joint (자동차용 볼조인트의 구조적 성능 예측)

  • Kim, Seong-Uk;Jeong, Gyeong-Il;Lee, Kwon-Hee;Lee, Dong-Jin;Lee, Myeong-Gon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.1
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    • pp.705-713
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    • 2018
  • An automotive ball joint connects the suspension system to the steering system and helps to enable rotational and linear motion between the two elements for steering. This study examines a ball joint used in medium and large-sized pickup trucks. Ball joints consist of a stud, socket, bearing, and plug. The main structural performance metrics of ball joints are the pull-out strength and push-out strength. These structural parameters must meet certain criteria to avoid serious accidents. Test and simulation methods are used to investigate the design requirements, but tests are time-consuming and costly. In this study, we modeled ball joints in SolidWorks and performed a finite element analysis in Abaqus to predict structural performance. The analysis was used to obtain the structural performance required for the static analysis of a 2D axisymmetric model. The uncertainties in the manufacturing of the ball joint were assumed to be the manufacturing tolerances, and the dimensional design variables were identified through case studies. The manufacturing tolerances at each level were defined, and the results were compared with experimental results.

Design of CIC Interpolators with Improved Passband and Transition Region for Underwater Acousitc Communication (통과대역 및 전이영역 특성이 개선된 수중음파통신용 CIC 인터폴레이터 설계)

  • Kim, Sunhee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.1
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    • pp.660-665
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    • 2018
  • Research into underwater wireless networks that enable the monitoring and controlling of the ocean environments has been continuing for disaster prevention and military proposes, as well as for the exploitation of ocean resources throughout the world. A research group led by Hoseo university has been studying a distributed underwater monitoring and controlling network. In this study, we developed an interpolator for acoustic communication between an underwater base station controller and underwater base station, which is included in this network. The underwater acoustic communication provided by this network defines four links whose sampling rates are different. Low power consumption is one of the most important requirements. Therefore, we adopted CIC interpolators, which are known to act as filters with a low power consumption, and some CIC interpolators with an appropriate changing rate were selected depending on the link. However, these interpolators have a large passband drop and wide transition region. To solve these problems, we added a compensator and half-band filter. After verifying the algorithm by using Matlab, we designed and verified it with Verilog-HDL in a ModelSim environment.

Design of a Neural Network PI Controller for F/M of Heavy Water Reactor Actuator Pressure (신경회로망과 PI제어기를 이용한 중수로 핵연료 교체 로봇의 구동압력 제어)

  • Lim, Dae-Yeong;Lee, Chang-Goo;Kim, Young-Baik;Kim, Young-Chul;Chong, Kil-To
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.3
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    • pp.1255-1262
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    • 2012
  • Look into the nuclear power plant of Wolsong currently, it is controlled in order to required operating pressure with PI controller. PI controller has a simple structure and satisfy design requirements to gain setting. However, It is difficult to control without changing the gain from produce changes in parameters such as loss of the valves and the pipes. To solve these problems, the dynamic change of the PI controller gain, or to compensate for the PI controller output is desirable to configure the controller. The aim of this research and development in the parameter variations can be controlled to a stable controller design which is reduced an error and a vibration. Proposed PI/NN control techniques is the PI controller and the neural network controller that combines a parallel and the neural network controller part is compensated output of the controller for changes in the parameters were designed to be robust. To directly evaluate the controller performance can be difficult to test in real processes to reflect the characteristics of the process. Therefore, we develope the simulator model using the real process data and simulation results when compared with the simulated process characteristics that showed changes in the parameters. As a result the PI/NN controller error and was confirmed to reduce vibrations.

An Approach to Developing Domain Architecture Based on Variability Analysis in Software Product Line (소프트웨어 프로덕트 라인에서 가변성 분석을 통한 도메인 아키텍처 개발 방법)

  • Moon, Mi-Kyeong;Yeom, Keun-Hyuk
    • Journal of KIISE:Software and Applications
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    • v.34 no.4
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    • pp.328-341
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    • 2007
  • When the decision to initiate a software product line has been taken, the first step is the domain analysis describing the variability in the requirements, the second important step is the definition of a domain architecture that captures the overall structure of a series of closely related products. A domain architecture can be a core asset in product line by describing the commonalities and variabilities of the products contained in the software product line. The variabilities, which are identified at each phase of the core assets development, are diverse in the level of abstraction. Therefore, it is important to clearly define, systematically identify, and explicitly represent variability at the architectural level. However, it is difficult to identify and represent the variability which should be considered at the architecture level, because these may be appeared in architecture elements and in architecture configuration. In this paper, we suggest a method of developing domain architecture as a core asset in product line where commonality and variability are explicitly considered. First of all, we will describe a domain architecture metamodel that can explicitly define commonality and variability concepts by extending the Object Management Group's ($OMG^{TM}$ Reusable Asset Specification eRAS) model. Using the domain architecture metamodel, architecture elements are defined and the variations that can be identified at the architecture level are classified into two types in according th abstract level. Additionally, we describe a domain architecture where commonality and variability are explicitly considered on basis of this metamodel.

The Impact of an Ontological Knowledge Representation on Information Retrieval: An Evaluation Study of OCLC's FRBR-Based FictionFinder (정보검색에 온톨로지 지식 표현이 미치는 영향에 대한 연구: OCLC의 FRBR기반 FictionFinder의 평가를 중심으로)

  • Cho, Myung-Dae
    • Journal of the Korean Society for information Management
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    • v.25 no.2
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    • pp.183-198
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    • 2008
  • With the purpose of enriching existing catalogues with FRBR, which is the Functional Requirements for Bibliographic Records, in mind, this paper aims to evaluate the impact of bibliographic ontology on the overall system's performance in the field of literature. In doing this, OCLC's FictionFinder(http://fictionfinder.oclc.org) was selected and qualitatively evaluated. In this study 40 university seniors evaluated the following three aspects using the 'transferring thoughts onto paper method': 1) In which ways is this FRBR-aware bibliographical ontology helpful? 2) Are the things which are initially attempted to be helped being helped? 3) Would users seeking one work in particular also see all other related works? In conclusion, this study revealed that, as Cutter claimed in his $2^{nd}$ rule of the library, collocations give added-value to the users and overall ontology provides better interface and usefulness. It also revealed that a system's evaluation with qualitative methodology helped to build full pictures of the system and to grip the information needs of the users when the system is developed. Qualitative evaluations, therefore, could be used as indicators for the evaluation of any information retrieval systems.

Korean Customer Attitudes Towards SNS Shopping

  • Cho, Young-Sang;Heo, Jeong-Yoon;Youn, Myoung-Kil
    • Journal of Distribution Science
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    • v.10 no.8
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    • pp.7-14
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    • 2012
  • As a new format of retailing, social shopping on SNS has rapidly grown in recent. Although there is much literature associated with customer behaviours in the academic world, little attention has been paid to identifying the shopping patterns of SNS shoppers. This paper will, thus, identify how perceived value has an impact on the buying intention of SNS shoppers, after illustrating what kind of factor influences the formation process of perceived value in the Korean marketplace. Given that SNS shoppers are for the most part 20s as well as 30s, the authors handed out questionnaires to them. Furthermore, based on literature review results, the conceptualised research model was developed. Despite lack of literature, the authors developed five constructs like price reduction, quantity- and time-limited message, product ranges, information-sharing, and required number of shoppers. The researchers made a considerable effort to identify the relationship between research concepts and each variable, based on a few research analysis methods such as frequency analysis, the Varimax rotation technique used orthogonal rotation, Cronbach's Alpha, PCA (Principle Component Analysis), and the like. Amongst the 5 variables used to measure the degree of influences on the perceived value as a social shopping characteristic, it has been evident that price cut, required minimum shoppers, product variety, and information-sharing have a positive impact on the perceived value formation processes of SNS customers. Also, this research implies that SNS retailers can differentiate themselves from other retailers by differently using the above factors. From a practitioner's point of view, these factors should be strategically used to increase the social shopping opportunities of SNS users. It is, furthermore, evident that the perceived value formed by the above 4 factors have played an important role in the buying decision process of SNS customers. In a sense, whether customers are aware of higher price cut rates, information-sharing, required minimum shoppers, and product variety has a positive impact on making buying decisions. From a retailer's point of view, online shopping mall operators are able to use blog as well as twitter to improve the buying intention as a marketing tool of social network, because the business activities provided by social shopping retailers, like the rapid, accurate responses to customer requirements, the provision of a variety of information, and the communications between customers are closely related to buying intentions. There are a few research limitations to conduct this empirical research. It was not easy to review prior papers, due to its lack. In spite of the increasing number of SNS shoppers in Korea, little research attention has been paid to this kind of research topic by academicians, because buying products or services through SNS is in its infancy. With regard to research populations, it would be difficult to generalise the research findings in Korea, owing to unbalanced respondent distribution. Considering the above research limitations as well as the growth of social shopping, many authors should pay considerable attention to SNS-related issues in the future, and develop the more sophisticated criteria to measure the characteristics of SNS shoppers.

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DESIGN AND IMPLEMENTATION OF HITL SIMULATOR COUPLEING COMMUNICATIONS PAYLOAD AND SOFTWARE SPACECRAFT BUS (통신탑재체와 소프트웨어 위성버스체를 통합한 HITL 시뮬레이터의 설계 및 구현)

  • 김인준;최완식
    • Journal of Astronomy and Space Sciences
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    • v.20 no.4
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    • pp.339-350
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    • 2003
  • Engineering qualification model payload for a communications and broadcasting satellite(CBS) was developed by ETRI from May, 2000 to April, 2003. For. the purpose of functional test and verification of the payload, a real-time hardware-in-the-loop(HITL) CBS simulator(CBSSIM) was also developed. We assumed that the spacecraft platform for the CBSSIM is a geostationary communication satellite using momentum bias three-axis stabilization control technique based on Koreasat. The payload hardware is combined with CBSSIM via Power, Command and Telemetry System(PCTS) of Electrical Ground Support Equipment(EGSE). CBSSIM is connected with PCTS by TCP/IP and the payload is combined with PCTS by MIL-STD-1553B protocol and DC harness. This simulator runs under the PC-based simulation environment with Windows 2000 operating system. The satellite commands from the operators are transferred to the payload or bus subsystem models through the real-time process block in the simulator. Design requirements of the CBSSIM are to operate in real-time and generate telemetry. CBSSIM provides various graphic monitoring interfaces and control functions and supports both pre-launch and after-launch of a communication satellite system. In this paper, the HITL simulator system including CBSSIM, communications payload and PCTS as the medium of interface between CBSSIM and communications payload will be described in aspects of the system architecture, spacecraft models, and simulator operation environment.

Analysis on relationship between operating problems and competitiveness of Busan container terminals (부산항터미널의 운영문제점과 경쟁력간의 관련성분석)

  • Ahn, Ki-Myung;Kim, Sung-Yong;Choo, Yeon-Gil;Kim, In-Su
    • Journal of Navigation and Port Research
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    • v.32 no.8
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    • pp.667-674
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    • 2008
  • In this paper, operational problems of Busan Port and competitiveness deciding factors are analyzed by field data research and interview with employees in shipping companies and terminal operation companies. In the analysis, the problems Busan Port currently has are identified as follows: 1) low price competitiveness, 2) Lack of new port back facilities and connecting transportion system 3) Lack of operation ability of container terminal 4) Inefficient pour labor supply system. In order to strengthen the competitiveness and leap up to a hub port in North East Asia, Busan port is investigated to enhance below requirements. 1) Hiring more equipment and increase productivity in terminal 2) Integrating terminal operation companies to react maximization of vessel 3) Maintaining cost advantages 4)Proactively inviting global carriers to participate in the terminal operation 5)Making business environment for Global Terminal Operator to participate in the terminal operation in order to take advantage of their global marketing power.

A Model of Natural Language Information Retrieval Using Main Keywords and Sub-keywords (주 키워드와 부 키워드를 이용한 자연언어 정보 검색 모델)

  • Kang, Hyun-Kyu;Park, Se-Young
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.12
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    • pp.3052-3062
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    • 1997
  • An Information Retrieval (IR) is to retrieve relevant information that satisfies user's information needs. However a major role of IR systems is not just the generation of sets of relevant documents, but to help determine which documents are most likely to be relevant to the given requirements. Various attempts have been made in the recent past to use syntactic analysis methods for the generation of complex construction that are essential for content identification in various automatic text analysis systems. Unfortunately, it is known that methods based on syntactic understanding alone are not sufficiently powerful to Produce complete analyses of arbitrary text samples. In this paper, we present a document ranking method based on two-level ranking. The first level is used to retrieve the documents, and the second level to reorder the retrieved documents. The main keywords used in the first level can be defined as nouns and/or compound nouns that possess good document discrimination powers. The sub-keywords used in the second level can be also defined as adjectives, adverbs, and/or verbs that are not main keywords, and function words. An empirical study was conducted from a Korean encyclopedia with 23,113 entries and 161 Korean natural language queries collected by end users. 850% of the natural language queries contained sub-keywords. The two-level document ranking methods provides significant improvement in retrieval effectiveness over traditional ranking methods.

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Improvement of a Verified Secure Key Distribution Protocol Between RFID and Readers (RFID와 리더간의 안전성이 검증된 키 분배 프로토콜의 개선)

  • Bae, Woo-Sik;Lee, Jong-Yun
    • The KIPS Transactions:PartC
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    • v.18C no.5
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    • pp.331-338
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    • 2011
  • The RFID system includes a section of wireless communication between the readers and the tags. Because of its vulnerability in terms of security, this part is always targeted by attackers and causes various security problems including the leakage of secret and the invasion of privacy. In response to these problems, various protocols have been proposed, but because many of them have been hardly implementable they have been limited to theoretical description and theorem proving without the accurate verification of their safety. Thus, this study tested whether the protocol proposed by Kenji et al. satisfies security requirements, and identified its vulnerabilities such as the exposure of IDs and messages. In addition, we proposed an improved RFID security protocol that reduced the number of public keys and random numbers. As one of its main characteristics, the proposed protocol was designed to avoid unnecessary calculations and to remove vulnerabilities in terms of security. In order to develop and verify a safe protocol, we tested the protocol using Casper and FDR(Failure Divergence Refinements) and confirmed that the proposed protocol is safe in terms of security. Furthermore, the academic contributions of this study are summarized as follows. First, this study tested the safety of a security protocol through model checking, going beyond theorem proving. Second, this study suggested a more effective method for protocol development through verification using FDR.