• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.583-590
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• 2008

최근 작업자 숙소 및 이송용 외에 작업용으로 사용 가능한 Barge선의 일종인 Accommodation Work Barge 선의 건조량이 증가 추세인 바 현재 중국에서 건조 중인 해당 선박의 HVAC & Refrigeration system에 대하여 정리하였다. 본 시스템은 R404A Direct expansion 냉각방식 (직접팽창방식)이 적용되었으며 HVAC system 중 Air conditioning 부분에 대해서는 선박의 각 Deck 기준으로 Zoning 하여 개별적인 Air handling unit와 Condensing unit를 구성하였으며 (각 unit의 용량은 필요용량의 100%), 냉동 창고의 Refrigeration system은 해당 격실 (육고, 어고, 야채고)에 각각 Unit cooler를 설치하고, Condensing unit를 기계실에 설치하였다. 장비는 전체 용량 100%에 대하여 항시 운전하는 100% 용량의 장비와 비상시에 운전하는 100% 용량의 예비 장비로 구성된다. 냉동 창고에 인접한 Dry provision store는 냉동 창고와는 별개로 중앙 공조기로부터의 냉각 공기를 이용하여 Spot cooling하였다. 본 System의 구성에 대한 장점 및 단점은 아래와 같다. 1. Air conditioning system이 각 Zone에 대하여 구성되므로 각 Zone에 대하여 제어가 가능하다. 2. Air con. 실에 Air handling unit와 Condensing unit가 설치되므로 냉매 배관의 길이가 짧다. 3. Air con. 실에 Air handling unit와 Condensing unit가 설치되므로 실내의 Maintenance space 상에 여유가 없다.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.138-144
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• 1997

The tidal deposits in the Haenam Bay, southwest coast of Korea, are stratigraphically divided at least into two units (Unit I of Holocene and Unit II of late Pleistocene) based on the obtained vibracoring sediments. In Unit I, clay minerals of illite, chlorite, kaolinite and smectite are observed as similar to those of the other modern tidal deposits. Of note, however, is the absence of smectite and chlorite in the upper part of Unit II compared with the clay mineral compositions of Unit I. It is concluded that the subaerial weathering and diagenetic effects rather than depositional processes are responsible for the positive and characteristic differences in clay mineral compositions between two units, that is, the upper part of Unit II was exposed subaerially and weathered diagenetically prior to the late Holocene transgression. Therefore, the bounding relationship between Unit I and Unit II is unconformable.

• Journal of the Korean Mathematical Society
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• v.54 no.1
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• pp.177-191
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• 2017

In this note we consider the right unit-duo ring property on the powers of elements, and introduce the concept of weakly right unit-duo ring. We investigate first the properties of weakly right unit-duo rings which are useful to the study of related studies. We observe next various kinds of relations and examples of weakly right unit-duo rings which do roles in ring theory.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.9-15
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• 2012

Vibrational film has been more employed in ear-phones or small type of speakers along with a wide use of portable multi-media equipments such as MP3 and MP4. However, the current hand work production process of diaphragms is inefficient. In this study, a die-and-mold and a single production forming machine are developed, and they result in a multi-production forming machine. The multi-production forming machine consists primarily of a film feeding unit and an unwinding unit. A vacuum suction device provides the film feeding unit, while the unwinding unit is obtained using an appropriate damper. The advantage of the developed single production forming machine is shown according to a proper voice test.

• The Mathematical Education
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• v.57 no.1
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• pp.37-54
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• 2018

Despite the significance of fraction in elementary mathematics education, it is not easy to teach it meaningfully in connection with real life in Korea. This study aims to investigate and analyze 3rd grade students' understanding on unit fraction concepts and on comparison of unit fractions and to identify the parts which need to be supplemented in relation to unit fraction. For these purposes, I reviewed previous studies and extracted chapters which cover unit fractions in elementary mathematics textbooks based on 2009 revised curriculums and analyzed teaching contexts and visual representations of unit fractions. From this point of view, I constructed a test which consists of three problems based on Chval et al(2013) to investigate students' understanding on unit fraction. To apply this test, I selected forty-one 3rd grade students and examined that students' aspects of understanding on unit fraction. The results were analyzed both qualitatively and quantitatively. In this study, I present the analysis results and provide implications and some didactical suggestions for teaching contexts and visual representations of unit fraction based on the discussion.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.470-473
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• 2009

We have developed a novel driving method, Six times Rate Driving(SRD) for the purpose of making cost competitive TFT-LCD. By applying SRD method to an a-Si TFT-LCD, the driving rate was increased six times as it was named but the number of data lines and so its D-Ics were reduced to one sixth of the conventional one which resulted in the cost saving of that much. We also newly designed the gate driver in order to avoid any expansion of the bezel width caused by applying SRD. Our newly developed driving technology, SRD was successfully applied to 7.0-inch WSVGA (1024 ${\times}$ 600) TFT-LCD which can be driven with only one data D-IC and here introduced.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.12
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• pp.9-19
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• 1997

This paper describes the design and FPGA implementation of a system control unit within a multiprocessor chip which can be used as a node processor ina massively parallel processing (MPP) caches, memory management units, a bus unit and a system control unit. Major functions of the system control unit are locking/unlocking of the shared variables of protected access, synchronization of instruction execution among four integer untis, control of interrupts, generation control of processor's status, etc. The system control unit was modeled in very high level using verilog HDL. Then, it was simulated and verified in an environment where trap handler and external interrupt controller were added. Functional blocks of the system control unit were changed into RTL(register transfer level) model and synthesized using xilinx FPGA cell library in synopsys tool. The synthesized system control unit was implemented by Xilinx FPGA chip (XC4025EPG299) after timing verification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.169-174
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• 2012

Reduction unit is one of the most important components for railway vehicle because torque of motor must be transmitted to wheels of vehicle by reduction unit. However, According to advanced studies, it has been often broke down due to the damage, fatigue and wear of gear. To solve this problem, defect diagnosis methods of gear have been mainly using the vibration diagnosis technology through vibration waveform and frequency analysis. However, We should know vibration characteristics of normal state reduction unit prior to defect diagnosis. So in this paper, We had analyzed vibration characteristics of reduction unit in order to utilize monitoring system development. Comparison of targets is the vibration characteristics of normal state reduction unit about Electric Multiple Unit(EMU) and the High-speed trains(KTX, KTX II).

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.291-300
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• 1999

Currently under development is an airborne auxiliary power unit with 100 Kw equivalent power, which is composed of a centrifugal compressor, a reverse annular combustor, and a radial turbine. Air-foil bearings are used in this power unit to eliminate the oil supplying system, which can reduce the system complexity and weight. The high speed generator is adopted as an electric power generation and engine starting system, which can also eliminate the reduction gear system. Not only electric power but also pneumatic power is provided by bleeding the compressed air This power unit is aimed for the multi-purpose use such as a primary power unit In the army weapon system, an auxiliary power and environmental control unit in a next-generation tank, and a smoke generating unit.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.670-673
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• 2008

Good mechanical properties of thin-film transistors on plastic substrates are an essential parameter in the development of robust flexible displays. In this paper, a careful investigation is carried out on TFT backplane on plastic substrates under cyclic bending conditions. Bending modes of tensile and compressive as well as parallel and perpendicular orientation-dependent bending of channel have been analyzed carefully. This analysis will be helpful in knowing the electro-mechanical performance boundaries of the TFT devices so as to determine the bending limitations of our flexible displays.