• 한국정밀공학회지
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• 제23권6호
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• pp.57-63
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• 2006

Gravitational centers of precise spinning components must coincide with the rotational centers of those to reduce noise and vibration and to extend those lift as well. Therefore quality control should be performed in the manufacturing process, in which the unbalance moments are accurately measured. In this paper 3-point weighing method is adopted to measure the unbalance moment of small-sized precision spinning elements using electronic scales with 0.1 mg resolution. Firstly methods to eliminate the fixture error and to reduce the effects of frictional force that is known as side effect, are proposed. A measuring system is developed and various experiments are performed to verify the proposed approach. The measured and calculated values are analysed in statistical methods, and this provides the errors of the measuring system. The results show that the proposed theory and test procedures gives reliable unbalance moments and gravitational centers.

• 해양환경안전학회지
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• 제6권1호
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• pp.11-22
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• 2000

The paper describes creation methods of background scenes to implement realistic virtual environments in the VRSS (Virtual Reality Ship Simulator). VRSS is next-generation system constructed with virtual tools in a virtual space. Thus, it could have many benefits compared to conventional ship simulators composed with heavy bridge mock-up system and wide visual presentations. In this work, we developed effective 3D object modeling techniques, and constructed virtual harbor scene by using 3D-Webmaster authoring tool. The virtual harbor was built with object-oriented 3D objects modeled to interact with user's action. With the immersion-type VR system, we created virtual harbor environments in a virtual space, and discussed on the naturalness of the scene with test results of SDMPA (Semantic Differential Method for Psychophysical Assessment) by 10 subjects. As the results of subject assessment, all of the participants could felt natural-like harbor. Therefore, we found that the proposed creation methods and procedures of background scene are enabling to fit to the full mission VRSS construction.

• Nuclear Engineering and Technology
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• 제29권2호
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• pp.148-157
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• 1997

A new capsule that has a unique structure in which the test environments including neutron flux and fluence, and irradiation temperature can be controlled precisely during irradiation, was conceptually designed. The capsule structure and instrumentation were successfully designed according to the JMTR's standard procedures of capsule design. Based on the target irradiation, the details of the irradiation such as neutron fluence and irradiation temperature ore calculated and the related capsule safety was evaluated. In addition, the effects of design parameters including the changes in inner-capsule configuration, heater capacity, and Helium gas pressure on the specimen temperature were analyzed with a computer program. Through these thermal and strength evaluations, this capsule was proved to be safe during the irradiation in the JMTR.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.675-680
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• 2001

The effect of unbonded capping system on high strength concrete(400~600kgf/$\textrm{cm}^2$), with respect to both ø10$\times$20 and ø15$\times$30cm specimens, has been investigated in accordance with ASTM C 1231 and our procedures based on the existing studies. Tests show that the ratios of test results obtained using unbonded cap to grinding system are 1.02 in both cylinder sizes. Also, based on the results of ø10$\times$20cm specimens using unbonded cap and ø15$\times$30cm specimens using grinding system, it has been proposed that the use of the former has to spread throughout whole laboratories in field.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.367-372
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• 2002

The waterproofing systems of concrete bridge deck are installed under the complex circumstances, such as traffic loading, weather, and the condition of the deck concrete. For assuring the effectiveness of waterproofing system, the materials and the construction method and timing ought to be suitably selected with the procedures of waterproofing and the system has to ensure the economical performances. First of all, we discussed whether the quality and performance criteria for highway bridge deck are resonable or not through the investigation of domestic and foreign criteria. The basic properties of waterproofing membranes on market and the performance of waterproofing systems of concrete bridge deck have also been investigated in the view of the damages frequently reported from job site. In this way, the causes and measures of damages, the guidelines of design, construction, quality control, and maintenance, the test methods and criteria of membranes and waterproofing system, are proposed.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.90-94
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• 1998

Self diffusion coefficients of $^{67}$Co and impurity diffusion coefficients of $^{51}$Mn and $^{65}$Zn in single crystalline CoO have been measured by applying different radioactive isotopes simultaneously. To compare the residual activity method and the tracer sectioning method we analyzed our tracer diffusion experiments by using both methods simultaneously. According to our experimental results, the diffusion coefficients obtained from both methods are identical within experimental error, demonstrating the relibility of our experimental procedures. The diffusion coefficients of all the isotopes obtained during these test experiments for the methodology are similar in magnitude and show similar dependences on oxygen partial pressure. These first observations indicate that impurity diffusion of Mn and Zn occur via a vacancy mechanism as known for self diffusion of cobalt.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1749-1751
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• 1998

Close to high power radio/radar transmitters there is a possibility that sparks may be occur at discontinuities in metallic structures. If these structures are in an area in which a flammable mixture may be present, there is a possibility that a fire or explosion may be caused by the sparking. A number of assessment procedures for quantification of the hazard have been produced. This paper reviews the bases of the British Standard covering ignition hazards by radio-frequency radiation and presents some ignition test apparatus to access these hazards.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.157-162
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• 2001

There are many economic and operational reasons to integrate fire alarm signaling system with other building automation system. Integration of this requires communication standard and careful design practices. The important point for this is also the development of intelligent control modules for replacing the conventional zone adapter in fire system. Therefore, this paper proposes an new conceptual design of the distributed fire alarm signaling system and a new intelligent control modules with LonTalk protocol. Newly proposed additions to LonWorks network make it very well suited for integrating fire systems with other building automation systems. Additionally, it is very important that best design practices, test procedures and building codes need to be modernized to accommodate Integrated building systems.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.22-26
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• 2007

In the fibre to the home (FTTH) era, it is expected that broadband network provisioning will require thousands of optical fibres to be accommodated in a central office for optical access networks. An optical fibre line testing system could be used to reduce maintenance costs and improve service availability depending on the PON's element manager capabilities and the maintenance procedures adopted by the network supplier. When monitoring optical fibres transmitting communication lights, a wavelength of 1625 nm is used for maintenance testing. The splitter installed optical filters allow the communication light to pass but that cut off the test light in the front of optical line terminals (OLTs) and optical network terminals (ONTs). In the economic point of view, We design new planer lightwave circuit splitter embedded filtter and study it optical property.

• Communications for Statistical Applications and Methods
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• 제22권3호
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• pp.209-222
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• 2015

Time series are used in many studies for model building and analysis. We must be very careful to understand the kind of time series data used in the analysis. In this review article, we will begin with some issues related to the use of aggregate and systematic sampling time series. Since several time series are often used in a study of the relationship of variables, we will also consider vector time series modeling and analysis. Although the basic procedures of model building between univariate time series and vector time series are the same, there are some important phenomena which are unique to vector time series. Therefore, we will also discuss some issues related to vector time models. Understanding these issues is important when we use time series data in modeling and analysis, regardless of whether it is a univariate or multivariate time series.