• International Journal of Safety
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• 제8권2호
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• pp.9-14
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• 2009

This paper describes analysis of risk voltage for grounding electrode where earth leakage current is injected. To assess risk voltage of grounding electrode, the grounding simulator and CDEGS program were used to obtain measured data and theoretical results of this study. The grounding simulator was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The shapes of grounding electrode model was ground rod. The potential rise was measured by grounding simulator, and the touch and step voltages were computed by CDEGS program. As a consequence, the potential rise of ground rod abruptly decreases with increasing the distance from the grounding electrode to the point to be tested. The touch voltage above the ground rod was low, but the step voltage was high. The measured results were compared with the computer calculated data and were known in good agreement.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2021년도 제64차 하계학술대회논문집 29권2호
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• pp.41-44
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• 2021

In this paper, we propose a monitoring system that can monitor gas leakage concentrations in real time and forecast the amount of gas leaked after one minute. When gas leaks happen, they typically lead to accidents such as poisoning, explosion, and fire, so a monitoring system is needed to reduce such occurrences. Previous research has mainly been focused on analyzing explosion characteristics based on gas types, or on warning systems that sound an alarm when a gas leak occurs in industrial areas. However, there are no studies on creating systems that utilize specific gas explosion characteristic analysis or empirical urban gas data. This research establishes a deep learning model that predicts the gas explosion risk level over time, based on the gas data collected in real time. In order to determine the relative risk level of a gas leak, the gas risk level was divided into five levels based on the lower explosion limit. The monitoring platform displays the current risk level, the predicted risk level, and the amount of gas leaked. It is expected that the development of this system will become a starting point for a monitoring system that can be deployed in urban areas.

• Asian Pacific Journal of Cancer Prevention
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• 제14권9호
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• pp.5441-5447
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• 2013

Purpose: To demonstrate the value of sequential determinations of pelvic drainage in the identification of increased risk of anastomotic leakage (AL) after anterior resection for rectal cancer with a double stapling technique. Patients and Methods: Between January 2004 and December 2011, data for the daily postoperative pH of pelvic drainage fluid in 753 consecutive patients with rectal cancer who initially underwent anterior resection with a double stapling technique were reviewed. All patients experienced a total mesorectal excision. Patients with anastomotic leakage (Group AL, n=57) were compared to patients without leakage (Group nAL, n=696). Patients with perioperatively abdominopelvic implants that were likely to affect pH value (determined at $25^{\circ}C$) other than leakage were excluded. Mean postoperative values were compared. Results: Anastomotic leakage was noted in 57 (7.6%) of 753 patients with rectal cancer. The diagnosis of AL was made between the $6^{th}$ and $12^{th}$ postoperative day (POD; mean $8^{th}$ POD). There was no significance of the daily average values of pH on POD1 & 2 in group AL while a significantly sharp declining mean pH value reached its diagnostic point of AL (p<0.001) on POD3. A cut-off value of 6.978 on the $3^{rd}$ POD maximized the sensitivity (98.7.0%) and specificity (94.7%) in assessing the risk of leakage. Conclusion: According to these results, an early and persistent declining of pH value of pelvic drainage fluid after rectal surgery with anastomosis, is a marker of AL. A cut-off value of 6.798 determined at $25^{\circ}C$ on POD3 maximizes sensitivity and specificity.

• 한국유체기계학회 논문집
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• 제11권5호
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• pp.7-14
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• 2008

Open channel type regenerative pump has been used in various industrial fields. It generates high pressure with low flow rate. However, it has low efficiency because of its complex flow pattern, We studied performance experiments and 3D numerical flow analysis of a regenerative pump. Through the numerical analysis, we could get the internal flow pattern and profile of a regenerative pump. Also, we examined leakage flow effects due to the gap between casing and impeller and stripper clearance. For the numerical analysis verification, we performed experiments and they had similar tendency at the design point.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.309-312
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• 1999

In recent years there has been a steady increase in geoenvironmental engineering projects where geotechnical engineering has been combined with environmental concerns. Many of these projects involve some investigation on contaminant and leachate flume in the ground and landfill. In this study, investigation on leachate around the waste landfill was carried out to detect the leaked and contaminated area. Many techniques such as geophysical, drilling and sampling method were applied. As a result of this study, the concentration of leachate and the point of leachate leaking around landfill were found out, and countermeasures for cut-off of leachate flow from landfill were investigated.

• Journal of Power Electronics
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• 제14권6호
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• pp.1233-1242
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• 2014

A new inverter topology for single-phase photovoltaic (PV) systems is proposed in this study. The proposed inverter offers a four-level voltage in its output terminals. This feature results in easier filtering in comparison with other conventional two-level or three-level inverters. In addition, the proposed four-level inverter (PFLI) has a transformer-less topology, which decreases the size, weight, and cost of the entire system and increases the overall efficiency of the system. Although the inverter is transformer-less, it produces a negligible leakage ground current (LGC), which makes this inverter suitable for PV grid-connected applications. The performance of the proposed inverter is compared with that of a four-level neutral point clamped inverter (FLNPCI). Theoretical analysis and computer simulations verify that the PFLI topology is superior to FLNPCI in terms of efficiency and suitability for use in PV transformer-less systems.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1999년도 추계학술발표회
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• pp.69-72
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• 1999

Now there has been a steady increase in the field of geoenvironmental engineering projects where geotechnical engineering has been combined with environmental concerns. Many of these projects involve some investigation on leachate flume in the waste landfill. In this study, investigation on leachate around the waste landfill was carried out to detect the leachate leaking area. Many techniques such as geophysical, drilling and sampling method were applied. As a result of this investigation, the concentration of leachate and the point of leachate leaking around landfill were analysed.

• International Journal of Advanced Culture Technology
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• 제9권4호
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• pp.355-362
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• 2021

Through the Korean version of the New Deal 2.0, manufacturing-oriented SMEs are facing a new environmental change called smart factory construction. In addition, SMEs are facing new security threats along with a contactless environment due to COVID-19. However, it is practically impossible to apply the previously researched and developed security management system to protect the core technology of manufacturing-oriented SMEs due to the lack of economic capacity of SMEs. Therefore, through research on security management systems suitable for SMEs, it is necessary to strengthen their business competitiveness and ensure sustainability through proactive responses to security threats faced by SMEs. The security management system presented in this study is a security management system to prevent technology leakage applicable to SMEs by deriving and reflecting the minimum security requirements in consideration of technology protection point of view, smart factory, and remote access in a non-contact environment. It is also designed in a modular form. The proposed security management system is standardized and can be selectively used by SMEs.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.350-353
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• 2009

The shielding enclosure is very essential device to test the electromagnetic wave power generated by various RF equipments. Some standards for the shielding enclosures were established to test them in right method. Generally, There are IEEE-STD-299 and MIL-STD-285 and NSA-65-6 of the method for measuring the effectiveness of shielding enclosures, the IEEE-STD-299 combined MIL-STD-285 and NSA-65-6 about the method for measuring shielding effectiveness(SE) about 1969 years, but, the measurement point of 299 proposal is many points(including shielding wall, seam, coner beat, shielding door, etc) and demand long time of measurement. To improve SE test method for shielding enclosures was studied and suggested to develop a proper test procedure. First, we measure reference level as frequency range and H/V polarization, secondly, measure leakage point, and finally, measure shield effect and calculate SE. Our method has a merit of the less measurement point than IEEE-STD-299, and shorten time than 299, and define representation SE of shielding enclosure effectively.

• 대한방사선치료학회지
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• 제16권1호
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• pp.11-19
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• 2004

서론 및 목적 : 세기변조 방사선치료와 전신 정위적 방사선치료에서 5mm이내의 위치 정확성확인 (L-gram)은 환자치료 목적 달성을 위한 중요한 QA과정의 하나이다. 이에 본원에서 제작한 scale point를 이용하여 L-gram 영상을 얻어 환자치료의 정확성을 향상시키고자 한다. 대상 및 방법 : 본원의 MLC 부착장비인 CL2100C/D, CL21EX에서 치료중인 IMRT, SRS환자를 대상으로 기존의 상품화된 port film graticule과 본원에서 제작한 MLC scale pointer를 비교 분석하였다. 결과 : MLC를 이용한 scale pointer는 beam의 확산까지 고려한 정확한 위치를 나타내었고 MLC의 교차로 생기는 pixel 모양의 형성을 통해 어떠한 위치에서도 정확한 확인이 가능했다. 결론 및 고찰 : L-gram 확인시 약간의 시간적 투자($1{\sim}2$분)로서 정확한 위치를 나타냄으로서 L-gram 확인시간 단축과 치료부위의 정확한 위치 확인을 할 수 있었다.