• 한국지진공학회논문집
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• 제24권3호
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• pp.141-148
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• 2020

For the important safety system, two or more units of identical equipment or redundant components with similar function were installed to prevent abnormal failure. If the failure probability of such equipment is independent, this redundancy could increase the system safety remarkably. However, if the failure of each component is highly correlated by installing in a structure or experiencing an earthquake event, the expected redundancy effect will decrease. Therefore, the seismic correlation of the equipment should be evaluated quantitatively for the seismic probabilistic safety assessment. The correlation effect can be explained in the procedure of constructing fragility curves. In this study, several methodologies to quantify the seismic correlation in the failure probability calculation for multiple components were reviewed and two possible ways considering the realistic situation were selected. Simple examples were tested to check the applicability of these methods. The conversion method between these two methods was suggested to render the evaluation using the advantages of each method possible.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.488-497
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• 2010

2001년 KORAIL에 도입된 8100대 신형 전기기관차는 독일 SIEMENS사의 BR152 모델을 국내 설정에 맞도록 들어와 부분 수정 및 보완 통하여, 2003년 8200대 신형 전기기관차를 탄생하도록 한 PROTOTYPE 이다. 8100대 신형전기기관차와 8200대 신형 전기기관차는 유사하지만, 일부 수정되고 개선된 부분 중의 하나가 객차 전원 공급(이하'HEP) 장치이다. 이에 본 논문은 8200대 신형 전기기관차의 HEP 장치에서 무궁화호 객차로 공급되는 HEP 전원의 고조파 왜율에 대하여 원제작사의 조합시험 결과를 바탕으로 현재 운용중인 KORAIL 8200대 신형 전기기관차의 HEP 전원의 고조파 왜율을 실측하여 상호 비교하고, 전원 공급 장치의 고조파 왜율에 대한 국제규격 및 현황을 설명하고자 한다.

• 전기학회논문지
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• 제56권11호
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• pp.1903-1909
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• 2007

As the electric power industry has been revolutionarily transformed such that the distributed energy resources have been interconnected with power systems and a variety of energy service providers have been appeared, the need of Consumer Energy Portal as a core of two-way communication and service infrastructure between power suppliers and consumers has been gradually increased. Consumer Energy Portal can be thought of as a combination of hardware and software enabling two-way communication between energy service providers and equipment within the consumers' premises or a physical and logical link between consumers' in-building networks and wide-area access networks. In other words, Consumer Energy Portal can make the way the power industry has been traditionally operated the web-based way, enabling two-way interactions between energy service providers and consumers and mutual networking between end users' equipment. Thus, Consumer Energy Portal can be a kind of Service portal that provides new value-added services and efficient power operations that in the past. In this paper, for ESPs' integrated resources management, demand side management and value-added service provision, we have established the two-way access network that can gather real-time metering data using ZigBee technology and control physically networked equipment.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.484-497
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• 2021

This paper proposes an extended time uncertainty analysis approach in Level 2 human reliability analysis (HRA) considering severe accident management (SAM) strategies. The method is a time-based model that classifies two time distribution functions-time required and time available-to calculate human failure probabilities from delayed action when implementing SAM strategies. The time required function can be obtained by the combination of four time factors: 1) time for diagnosis and decision by the technical support center (TSC) for a given strategy, 2) time for strategy implementation mainly by the local emergency response organization (ERO), 3) time to verify the effectiveness of the strategy and 4) time for portable equipment transport and installation. This function can vary depending on the given scenario and includes a summation of lognormal distributions and a choice regarding shifting the distribution. The time available function can be obtained via thermal-hydraulic code simulation (MAAP 5.03). The proposed approach was applied to assess SAM strategies that use portable equipment and safety depressurization system valves in a total loss of component cooling water event that could cause reactor vessel failure. The results from the proposed method are more realistic (i.e., not conservative) than other existing methods in evaluating SAM strategies involving the use of portable equipment.

• Biomolecules & Therapeutics
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• 제22권4호
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• pp.355-362
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• 2014

We have developed a fully automated high throughput drug screening (HTDS) system based on the microfluidic cell culture array to perform combinational chemotherapy. This system has 64 individually addressable cell culture chambers where the sequential combinatorial concentrations of two different drugs can be generated by two microfluidic diffusive mixers. Each diffusive mixer has two integrated micropumps connected to the media and the drug reservoirs respectively for generating the desired combination without the need for any extra equipment to perfuse the solution such as syringe pumps. The cell array is periodically exposed to the drug combination with the programmed LabVIEW system during a couple of days without extra handling after seeding the cells into the microfluidic device and also, this device does not require the continuous generation of solutions compared to the previous systems. Therefore, the total amount of drug being consumed per experiment is less than a few hundred micro liters in each reservoir. The utility of this system is demonstrated through investigating the viability of the prostate cancer PC3 cell line with the combinational treatments of curcumin and tumor necrosis factor-alpha related apoptosis inducing ligand (TRAIL). Our results suggest that the system can be used for screening and optimizing drug combination with a small amount of reagent for combinatorial chemotherapy against cancer cells.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.358-362
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• 1995

Precision electronic equipments are composed of sophisticated microcircuits that are extremely vulnerable to lightning-caused voltage spike. This transient voltage spike may cause upset, latent failure or interference on electronic equipments. In order to develop efficient lightning protection measures on AC power lines for a road traffic controller, experimental surge immunity tests were conducted according to IEC standard 801-5. The combination of gas tube arrester and metal-oxide varistor was installed at the input of AC power lines and the silicon avalanche suppressor installed at the output of DC power supply as lightning protection measures.

• Preventive Nutrition and Food Science
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• 제12권3호
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• pp.167-172
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• 2007

This study was conducted to determine the effect of hygienic processing (HP) on the reduction of microorganisms during manufacturing of saengshik with two vegetables (carrots and cabbage) and two grains (barely and glutinous rice) compared to general processing (GP). For GP, distilled water was used for washing raw materials and equipment. For HP, aqueous ozone (3 ppm) in combination with 1% citric acid and 70% alcohol were used for washing raw materials and the equipment, respectively. In carrots, after cutting, total aerobic bacteria (TAB), yeast and mold (YM) and coliforms were significantly increased to 5.19, 8.04 and 2.08 ($log_{10}$ CFU/g), respectively (p<0.05). Washing effectively reduced the increased microorganisms from cross contamination during cutting, but cross contamination increased with subsequent GP drying and milling procedures to 8.56, 8.27 and 3.71 ($log_{10}$ CFU/g) for TAB, YM and coliforms, respectively (p<0.05). On the other hand, HP washing of carrots with 3 ppm ozone in combination with 1% citric acid showed higher antimicrobial effect than GP washing, significantly decreasing the number of microorganisms (p<0.05). Further cross contamination did not occur through drying and milling due to cleaning the equipments with 70% alcohol prior to processing. After milling, the number of TAB, YM and coliforms were significantly decreased to 3.89, 4.47 and not detectable level ($log_{10}$ CFU/g), respectively (p<0.05). Similar results were observed in cabbage and grains. During storage for two months at different temperatures (22 or $4^{\circ}C$), there were no changes in numbers of spoilage microorganisms in the packaged saengsik after either processing. This suggests the importance of HP for the reduction of microorganisms during saengsik production, and demonstrates the effectiveness of disinfection at each processing stage in minimizing contamination levels to enhance microbial safety of saengshik products.

• 한국추진공학회지
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• 제19권1호
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• pp.76-86
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• 2015

대한민국의 새로운 우주발사체인 KSLV-II에는 적합한, 자신만의 발사운용을 위해서 새로운 발사대 시스템 개발이 요구된다. 새로운 발사대시스템은 운용 효율성의 극대화와 경제성 측면에서 나로우주센터의 기존 KSLV-I 발사대 인근에 구축될 예정이다. 발사대시스템은 통상 기계설비, 전기설비, 그리고 추진제설비의 세 가지 지상설비들로 구성되는데, 이 중 추진제공급설비는 발사체 운용에 필요한 추진제 및 각종 가스류를 보관하고 조건에 맞게 공급하는 시스템들의 집합체로 정의된다. 본 논문에서는 한국형발사체 발사대시스템의 추진제공급설비에 대한 구성 및 기능과, 발사 시 발생하는 고온 고속의 연소 후류를 안전하게 배출하기 위한 화염유도로 형상에 대한 설계 결과를 소개하고자 한다.

• 한국음향학회지
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• 제33권2호
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• pp.111-117
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• 2014

본 논문은 전자장비의 구조기인소음 (structure-borne noise)의 실험적 저감방안 검토에 대한 내용을 다루었다. 수냉식 전자장비의 유일한 소음원인 냉각장치를 목업(mock-up)으로 제작하여 소음 특성을 파악하였으며, 전원에 의한 영향, 구조체 강성에 의한 영향, 팬 고정부위의 절연에 의한 효과, 마운트의 공진주파수가 미치는 영향 등에 대한 검토를 수행하였다. 이를 반영하여 제작된 전자장비 프로토타입의 소음 특성을 파악하였으며, 구조기인소음을 저감시키기 위하여 작동회전수(rpm) 조합, 마운트 종류 및 설치방법 등에 대하여 검토하였다. 냉각팬 작동 주파수의 1차, 4차 성분에 의하여 소음이 크게 발생하며, 구조체 강성증가, 팬 고정부위 절연, 마운트 공진주파수 저하, 작동회전수조합, 마운트 선정방법 등에 의하여 전자장비의 구조소음을 저감시킬 수 있음을 확인하였다.

• 한국기계가공학회지
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• 제13권5호
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• pp.28-34
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• 2014

A planetary gear train is more compact and endures greater amounts of transmission power compared to other gear systems. Although planetary gear systems operate in small volumes, they are capable of very high efficiency due to the compact combination of their gears in the planetary gear system. They also have outstanding efficiency of only 3% for power transmission, tantamount to the power loss that occurs in each of the shift stages. Given these advantages, planetary gear systems are used in the driving systems of, which are widely used in automobile transmissions, machine tools, semiconductor equipment, and in other areas in industrial fields. Current structural equipment requires higher efficiency and greater torque levels. According to these needs, we have designed a complex planetary gear system which creates higher levels of torque. In this paper, an evaluation of strength designs for the proposed planetary gear system was conducted to ensure the stability of the gear. In addition, a durability analysis based on Miner's rule was performed using RS B 0095 device.