• 대한산업공학회지
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• 제29권1호
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• pp.21-31
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• 2003

Determination of operational dimensions and tolerances is complex if there exist inconsistencies between operational and design specifications. Dimension and tolerance charts (D&T charts) have been used to establish the relationships among operational dimensions in complex machining. This chart proves that individual operations can be harmonized when they are interconnected. However, it is hard to generate the chart manually. Because operational dimensions and tolerances must meet the design specifications, the dimensions and tolerances of interconnected operations have to be verified serially for economical operations. In this paper, the chart is automatically generated from the interconnected operations. More importantly, all operational dimensions and tolerances displayed in the chart have been verified by using LP to meet the design specifications. Finally, the chart is converted to an operational routing sheet that contains a detailed process plan along with cutting speed, feed rate, and operational references based on material hardness, surface finish, and tool nose radius.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2001년도 춘계학술대회 발표논문집
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• pp.124-128
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• 2001

A present semiconductor cleaning technology is based upon RCA cleaning technology which consumes vast amounts of chemicals and ultra pure water(UPW) and is the high temperature Process. Therefore, this technology gives rise to the many environmental issues, and some alternatives such as functional water cleaning are being studied. The electrolyzed water was generated by an electrolysis system which consists of anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in anode and cathode chambers, respectively. In case of NH$_4$Cl electrolyte, the oxidation-reduction potential and pH for anode water(AW) and cathode water(CW) were measured to be +1050mV and 4.8, and -750mV and 10.0, respectively. AW and CW were deteriorated after electrolyzed, but maintained their characteristics for more than 40 minutes sufficiently enough for cleaning. Their deterioration was correlated with CO$_2$ concentration changes dissolved from air. It was known that AW was effective for Cu removal, while CW was more effective for Fe removal. The particle distributions after various particle removal processes maintained the same pattern. In this work, RCA consumed about 9$\ell$chemicals, while EW did only 400$m\ell$ HCI electrolyte or 600$m\ell$ NH$_4$Cl electrolyte. It was hence concluded that EW cleaning technology would be very effective for eliminating environment, safety, and health(ESH) issues in the next generation semiconductor manufacturing.

• 한국염색가공학회지
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• 제32권1호
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• pp.65-71
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• 2020

Electrical energy is used for heating and cooling because electric cars do not have engines and cooling water. The downside is that when the heating and cooling system is applied to electric vehicles, about 40 percent of the energy is spent on heating and cooling, which is less efficient in winter. This has increased demand for electric vehicle battery efficiency. In this study, the condensation and dispersion of carbon nanotubes were controlled, and carbon fibers and composite slurry were manufactured without binders to manufacture paper. Manufactured by content showed the highest heat generation characteristic at 143℃ with a carbon fiber content ratio of 20wt% and confirmed that the heat temperature rises with increasing pressure. The plane heaters made through this study can be applied to a variety of products other than electric vehicles because they can be simplified by process and high temperature.

• 전기학회논문지
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• 제65권8호
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• pp.1347-1354
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• 2016

This paper presents optimal operational scheduling model and economic assessment of Li-ion battery energy storage systems installed in non-residential customers. The operation schedule of a BESS is determined to minimize electric bill, which is composed of demand and energy charges. Dynamic programming is introduced to solve the nonlinear optimization problem. Based on the optimal operation schedule result, the economics of a BESS are evaluated in the investor and the social perspective respectively. Calculated benefits in the investor or customer perspective are the savings of demand charge, energy charge, and related taxes. The social benefits include fuel cost savings of generating units, construction deferral effects of the generation capacity and T&D infra, and incremental CO2 emission cost impacts, etc. Case studies are applied to an large industrial customer that shows similarly repeated load patterns according to days of the week.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.50-54
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• 1996

최근들어 전력수요와 상시 전력공급이 요구되는 시설이 증가함에 따라 독립적으로 전력을 공급할 수 있는 상용 또는 비상용발전기가 많이 이용되고 있는 추세이다. 이러한 소형 발전시스템에는 디젤엔진이나 터빈 엔진에 발전기를 연결하여 전력을 공급하는 코젠 시스템(co-generation system)이 주로 이용된다[1]. 일반적으로 코젠시스템은 운전중에 매우 높은 수준의 소음이 발생되므로 건물 주변이나 사람의 왕래가 잦은 곳에 설치되는 경우에 필히 소음저감을 위한 대책이 필요하게 된다[2,3]. 본 사례는 대형놀이시설의 전력공급용으로 설치된 옥내(발전실내)의 상용/비상용 발전기(3600 KW 디젤엔진 2대)에서 발생한 상당량의 소음이 놀이시설주변까지 전달되어, 소음원 및 그 전달경로를 규명하고 대책을 수립한 내용이다. 놀이시설의 개장을 앞두고 소음문제가 발생되었기 때문에 신속하고 현실적인 해결책의 적용이 요구되었으므로 발전기 및 발전실 주변의 소음레벨 및 주파수특성의 분석을 통하여 주소음원을 규명하는 방법을 택했다. 분석결과로부터 주 소음원은 엔진 배기구에서 발생되는 저주파수 특성을 갖는 소음으로 규명되었고, 그 주파수특성에 적합한 흡음 및 반사특성을 동시에 갖는 조합형 2차 소음기를 추가로 설치하여 발전실 주변소음레벨을 크게 저감할 수 있었다.

• 한국멀티미디어학회논문지
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• 제7권6호
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• pp.824-831
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• 2004

This paper presents the java bytecode-to-.NET MSIL intermediate language translator which enables the execution of the java program in .NET environments without JVM(java Virtual Machine), translating bytecodes produced by compiling java programs into MSIL codes. Java, one of the most widely used programming languages recently, is the language invented by James Gosling at Sun Microsystems, which is the next generation language independent of operating systems and hardware platforms. Java source code is compiled into bytecode as intermediate code independent of each platform by compiler, and also executed by JVM. .NET language such as C# and .NET platform in Microsoft Corp. has been developed to meet the needs of programmers, and cope with Java and JVM platform of Sun Microsystems. After compiling, a program written in .NET language is converted to MSIL code, and also executed by .NET platform but not in JVM platform. For this reason, we designed and implemented the java bytecode-to-.NET MSIL translator system for programs written in java language to be executed in the. NET platform without JVM. This work improves the execution speed of programs, enhances the productivity, and provides a environment for programmers to develop application programs without limitations of programming languages.

• 천문학회보
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• 제44권1호
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• pp.82.2-82.3
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• 2019

Korea Astronomy and Space Science Institute (KASI), in collaboration with the NASA Goddard Sparce Flight Center (GSFC), will develop a next generation coronagraph for the International Space Station (ISS). COronal Diagnostic EXperiment (CODEX) uses multiple filters to obtain simultaneous measurements of electron density, temperature, and velocity within a single instrument. CODEX's regular, systematic, comprehensive dataset will test theories of solar wind acceleration and source, as well as serve to validate and enable improvement of space-weather/operational models in the crucial source region of the solar wind. CODEX subsystems include the coronagraph, pointing system, command and data handling (C&DH) electronics, and power distribution unit. CODEX is integrated onto a standard interface which provides power and communication. All full resolution images are telemeters to the ground, where data from multiple images and sequences are co-added, spatially binned, and ratioed as needed for analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권11호
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• pp.4203-4223
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• 2021

Accelerated by the Internet of Things (IoT), the need for further technical innovations and developments within wireless communications beyond the fifth generation (B5G) networks is up-and-coming in the past few years. High altitude platform station (HAPS) communication is expected to achieve such high levels that, with high data transfer rates and low latency, millions of devices and applications can work seamlessly. The HAPS has emerged as an indispensable component of next-generations of wireless networks, which will therefore play an important role in promoting massive IoT interconnectivity with 6G. The performance of communication and key technology mainly depend on the characteristic of channel, thus we propose an efficient Markov chain based channel model, then analyze the HAPS communication system's uplink capability and swing effect through experiments. According to the simulation results, the efficacy of the proposed scheme is proven to meet the requirements of ubiquitous connectivity in future IoT enabled by 6G.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.851-859
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• 2021

Small PWR can be used for power generation and heating. Considering that small PWR has the characteristics of flexible operating conditions and complex operating environment, the controller designed based on single power level is difficult to achieve the ideal control of small PWR in the whole range of core power range. To solve this problem, a flexible switching controller based on fuzzy controller and LQG/LTR controller is designed. Firstly, a core fuzzy multi-model suitable for full power range is established. Then, T-S fuzzy rules are designed to realize the flexible switching between fuzzy controller and LQG/LTR controller. Finally, based on the core power feedback principle, the core flexible switching control system of small PWR is established and simulated. The results show that the flexible switching controller can effectively control the core power of small PWR and the control effect has the advantages of both fuzzy controller and LQG/LTR controller.

• 로봇학회논문지
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• 제18권3호
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• pp.299-307
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• 2023

In the midst of accelerating wars around the world, unmanned robot technology that can guarantee the safety of human life is emerging. ERP-42 is a modular platform that can be used according to the application. In the field of defense, it can be used for transporting supplies, reconnaissance and surveillance, and medical evacuation in conflict areas. Due to the nature of the military environment, atypical environments are predominant, and in such environments, the platform's path followability is an important part of mission performance. This paper focuses on reducing the minimum turning radius in terms of improving path followability. The minimum turning radius of the existing 2WS/2WD in-wheel platform was reduced by increasing the torque of the independent driving in-wheel motor on the rear wheel to generate oversteer. To determine the degree of oversteer, two GPS were attached to the center of the front and rear wheelbases and measured. A closed-loop speed control method was used to maintain a constant rotational speed of each wheel despite changes in load or torque.