• 한국물환경학회지
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• 제26권1호
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• pp.28-34
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• 2010

This study was conducted to assess the validity of fecal coliforms to fecal streptococci ratio (FC/FS) for distinguishing the human from animal origin of fecal pollution in surface water. FC/FS ratio determined in effluent from municipal wastewater and human feces treatment plant (WWTP) and in downstream close to discharge of human feces was above 4 which indicates human origin. However FC/FS ratios determined seasonally in other water zones of the Nakdong River, even in the same sampling site, varied differently (above 4 or less than 0.7) due to different survival time of FC and FS and other environmental factors such as rainfall in watershed. Compared to other season, FC/FS ratios in winter were much lower regardless of the origin. It is concluded that the FC/FS ratio determined in surface water is not always valid for determining the origin of fecal pollution.

• 한국환경보건학회지
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• 제42권2호
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• pp.102-111
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• 2016

Objectives: This study was conducted to evaluate the use of polyurethane foam disk passive air samplers (PUF PAS) for better measurement of atmospheric polychlorinared dibenzo-p-dioxins/furans (PCDD/Fs) concentrations compared to PUF PAS combined with high volume air samplers (HVS). Methods: Air samples were collected by a low volume air sampler (LVS) and PUF PAS. A total of two pairs were continuously collected for six months, but the PUF was replaced every two months. Results: A good correlation was shown ($R^2=0.8595$, p<0.0001) between atmospheric PCDD/Fs concentration measured by the LVS and PUF PAS. The average air sampling rate ($1.5m^3/day-sampler$) of all PCDD/Fs congeners showed a middle of the means which were measured using a HVS by other researchers in different cities. In addition, the air sampling rates of the LVS for each congener made less difference than did those of the HVS. Conclusion: It was found that measurements using the LVS were less influenced by atmospheric peak PCDD/Fs concentrations. However, trace POPs such as PCDD/Fs may involve relatively large analytical errors in measurement, and as a result the air sampling rate of the respective PCDD/Fs isomer is also likely to involve errors. The method of using a regression straight line between the concentrations obtained from the LVS and those from the PUF PAS was judged higher than the method using the air sampling rate, since the former compensated for the experimental errors in the process of evaluation of atmospheric PCDD/F concentrations using the PUF PAS.

• Environmental Analysis Health and Toxicology
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• 제22권1호
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• pp.49-55
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• 2007

Three kind of ASE (Accelerated Solvent Extraction) and SPMDs (Semi-Permeable Membrane Devices) combined methods (ASE-SPMDs, ASE-accelerated SPMDs and SPMDs without extraction) and general Soxhlet-GPC were compared each other for the analysis of PCDD/FS in sediment. The average recovery rate of three types ASE and SPMDs combined methods (108.1%) were higher than that of the Soxhlet-GPC (79.5%) for three samples in each method using surrogate internal standards. The average coefficient of variation (10%, $2.1{\sim}25.2%$) for each congener of PCDD/Fs shows the reasonable results. Total PCDD/Fs concentrations after SPMDs without extraction were quite low, but those after ASE-SPMDs and ASE-accelerated SPMDs methods were close to the Soxhlet-GPC. Thus, the ASE-SPMDs and ASE-accelerated SPMDs methods are considered as the excellent pre-treatments method because they need less solvent and time without quality degradation.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제20권12호
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• pp.623-631
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• 2014

데이터 중복제거 파일시스템인 LessFS와 SDFS의 성능을 비교하면, LessFS는 CPU 점유율과 수행 시간에서 성능이 우수하고, SDFS는 중복제거 이후 저장소 사용량이 다른 파일시스템보다 1/8 정도의 이점을 가지고 있다. 본 논문은 SDFS의 장점인 중복제거 이후 저장소 사용량 감소와 LessFS의 장점인 낮은 CPU 점유율과 수행 시간 감소의 장점을 지니는 새로운 방식을 제안한다. SDFS의 Dedup File Engines (DFE) n개를 이용하되, Dedup Storage Engines (이하 DSE) 1개를 두어 중복제거 데이터의 정합성과 일관성을 유지하는 방식이다. 제안하는 방식을 2개의 DFE와 1개의 DSE를 가진 시험환경에 구현하고 성능 비교를 수행한다.

• 한국정보통신학회논문지
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• 제24권2호
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• pp.149-157
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• 2020

오늘날 사용자의 데이터 증가에 따른 데이터 중복으로 인해 다양한 중복 제거 연구가 이루어졌다. 그러나 상대적으로 개인 스토리지에 대한 연구는 미진하다. 개인 스토리지는 고성능 컴퓨터와는 다르게 CPU와 메모리의 자원 사용을 줄이면서 중복 제거를 수행할 필요가 있다. 본 논문에서는 개인 스토리지에서 중복 제거율을 적절히 유지하며 부하를 낮추기 위해 파일의 타입과 크기에 따라 FSC(Fixed Size Chunking)와 WFH(Whole File Chunking)를 선택적으로 적용하는 적응형 알고리즘을 제안한다. 제안한 파일 시스템은 LessFS에 비해 최초 파일 Write 시에는 Write 소요 시간은 1.3배 이상 높았으나 메모리의 사용은 3배 이상 감소하였고, Rewrite 시는 LessFS에 비하여 Write 소요시간이 2.5배 이상 빨라지는 것을 실험을 통하여 확인하였다.

• 대한지역사회영양학회지
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• 제2권3호
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• pp.406-416
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• 1997

Teacher's satisfaction with school lunch programs run by foodservice(FS) management types were surveyed with questionnaire at 5 middle and 4 elementary schools. The 88 middle and 104 elementary school teachers who participated and schools' FS management were of 5 types : self/conventional, contracted/conventional, contracted/commissary and contracted/dosirak delivery. Most teachers knew correctly their schools' present FS management types and thoroughly understood the main reasons for needing school lunch program with proper nutrition, better taste and balanced diets in addition to the first reason its less work than preparing homelunches. Teacher's satisfactions with their present school FS were high in self/conventional and contracted/conventional and was very low in contracted/commissary and contracted/ dosirak Taste, hygiene, nutrition and dining facilities in turn were pointed out to be improved : firstly hygiene in the self and firstly taste in the contracted. Particularly dining-rooms were found to have narrow space, uncomfortable chairs and tables, unclean, and having unpleasant smells. Teachers observed that the overall students' food habits such as eating more various foods and better table manners through that school lunch programs, particularly the self-managed types were improved. Conclusively most teachers emphasized school lunch programs to be continued and preferred self-managed types and contracted/conventional types as the second best in having less work to manage, better, taste, nutrition and hygiene, less cost and better nutrition education in turn. And they thought school founders should handle the finances needed to newly establish or repair the school FD facilities, otherwise provided with the partial aid of student's parents.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권2호
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• pp.202-207
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• 2015

A CMOS relaxation oscillator, with high robustness over process, voltage and temperature (PVT) variations, is designed in $0.18{\mu}m$ CMOS. The proposed oscillator, consisting of full-differential charge-discharge timing circuit and switched-capacitor based voltage-to-current conversion, could be expanded to a simple open-loop frequency synthesizer (FS) with output frequency digitally tuned. Experimental results show that the proposed oscillator conducts subcarrier generation for frequency-modulated ultra-wideband (FM-UWB) transmitters with triangular amplitude distortion less than 1%, and achieves frequency deviation less than 8% under PVT and phase noise of -112 dBc/Hz at 1 MHz offset frequency. Under oscillation frequency of 10.5 MHz, the presented design has the relative FS error less than 2% for subcarrier generation and the power dissipation of 0.6 mW from a 1.8 V supply.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.13-22
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• 2002

This paper presents characteristics of CrOx thin-film Strain gauge pressure sensors, which were deposited on SUS630 diaphragm by DC reactive magnetron sputtering in an argon-Oxide atmosphere(Ar-(10%)$O_2$). The optimized condition of CrOx thin-film strain gauges were thicknessrange of 2500$\AA$ and annealing condition ($350^{\circ}C$, 3 hr) in Ar-10 %$O_2$deposition atmosphere. Under optimum conditions, the CrOx thin-films for strain gauge is obtained a high resistivity, $\rho$=156.7$\mu$$\Omega$cm, a low temperature coefficiect of resistance, TCR=-86 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal, 15. The output sensitivity of pressure sensor obtained is 2.46㎷/V and the maximum non-linearity is 0.3%FS and hysteresis is less than 0.2%FS. The output characteristics of pressure transmitter obtained is 4~20㎃ and total accuracy is less than $\pm$0.5%FS. In those conclusions, CrOx thin film pressure sensors is quite satisfactory for many applications in industrial electronics.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.180-186
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• 2014

Objectives: The purpose of this in vitro study was to evaluate the microleakage and penetration of fissure sealant in permanent molar teeth with fluorosis after pretreatment of the occlusal surface. Materials and Methods: A total of 120 third molars with mild dental fluorosis were randomly divided into 6 groups (n = 20). The tooth surfaces were sealed with an unfilled resin fissure sealant (FS) material. The experimental groups included: 1) phosphoric acid etching (AE) + FS (control); 2) AE + One-Step Plus (OS, Bisco) + FS; 3) bur + AE + FS; 4) bur + AE + OS + FS; 5) Er:YAG laser + AE + FS; and 6) Er:YAG laser + AE + OS + FS. After thermocycling, the teeth were immersed in 0.5% fuchsin and sectioned. Proportions of mircoleakage (PM) and unfilled area (PUA) were measured by digital microscope. Results: Overall, there were significant differences among all groups in the PM (p = 0.00). Group 3 showed the greatest PM, and was significantly different from groups 2 to 6 (p < 0.05). Group 6 showed the lowest PM. Pretreatment with Er:YAG with or without adhesive led to less PM than bur pretreatment. There were no significant differences among groups in PUA. Conclusions: Conventional acid etching provided a similar degree of occlusal seal in teeth with fluorosis compared to those pretreated with a bur or Er:YAG laser. Pretreatment of pits and fissures with Er:YAG in teeth with fluorosis may be an alternative method before fissure sealant application.

• 한국건설순환자원학회논문집
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• 제7권4호
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• pp.413-422
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• 2019

콘크리트 혼화재인 보통 포틀랜드 시멘트를 대체하기 위하여 페로실리콘 산업부산물을 적용하였다. 페로실리콘의 원재료 비표면적, 비중과 같은 기초물성은 실리카퓸과 매우 유사하다. 따라서 전체 혼화재 중량의 10%를 페로실리콘 또는 실리카퓸으로 치환한 콘크리트와 모르타르를 제작하여 페로실리콘의 혼화재로써의 사용 타당성을 평가하였고, 보통 포틀랜드 시멘트, 페로실리콘, 실리카퓸 콘크리트에 대한 비교 분석 결과를 나타냈다. 페로실리콘 콘크리트의 수화특성은 X선 회절 분석을 통하여 수행하였다. 페로실리콘 콘크리트는 압축강도, 염분침투 저항성, 공극 저감의 측면에서 보통 포틀랜드 시멘트 콘크리트 보다 장점을 보였으나 그 정도는 실리카퓸 보다 낮았다. 페로실리콘 콘크리트에 대하여 알칼리-실리카 반응에 의한 팽창 가능성이 확인되었는데 이는 실리카 입자의 뭉쳐진 덩어리 크기 때문인 것으로 판단된다.