• 조명전기설비학회논문지
• /
• 제19권1호
• /
• pp.101-108
• /
• 2005

도로에 설치된 가로등설비는 감전위험성에 노출된 취약한 구조로 급격한 호우로 인한 침수발생으로 매년 감전사고자가 다수 발생하고 있는 실정이다. 이에 가로등설비에서의 감전사고를 방지하기 위해, 실제 주요간선 도로 현장에서의 조사가 수행되었다. 가로등 분전함의 회로구성, 배선방법, 접지도체, 등주 등에 대해 실태조사가 실시되었고 관련 규정의 분석 및 문제점이 제시되었다. 또한 국내${\cdot}$외 가로등설비의 실태조사를 통해 비교 및 분석되었고, 이를 토대로 관련 규격이 개정되었다. 현장실태조사 및 관련규정의 분석을 통해, 주요간선 도로에 설치된 가로등설비에서의 감전사고에 대한 효과적인 예방대책을 확립하는데 실질적 자료를 제시하고자 한다. 향후 분석 자료는 가로등설비 뿐만 아니라 도로상의 다른 전기설비의 안정화 및 전기재해를 감소시키는데 활용될 수 있다.

• 한국식품저장유통학회지
• /
• 제19권6호
• /
• pp.813-817
• /
• 2012

신선절단 '후지' 사과의 갈변도에 화학물질(ascorbic acid, cystein, sodium chloride, magnesium chloride, calcium chloride, histidine: 1% 용액), 한약재(갈근, 당귀, 산약, 오약, 천궁, 황기: 1% 추출액), 가열(절단과실과 원형과실, $40-60^{\circ}C$ 증류수) 및 코팅(albumin, dextrin, sucrose poly ester, whole soy flour: 0.5-4% 용액) 처리가 미치는 영향을 조사하였다. 각 처리방법별 신선절단 사과의 갈변도는 1% calcium chloride 용액 처리, 황기 추출물 처리, 3% dextrin과 1% whole soy flour 코팅 처리에 의해 가장 낮은 수준을 보였다. 가열처리의 갈변도는 절단과실 처리시에는 $50^{\circ}C$에서, 원형과실 처리시에는 $45^{\circ}C$에서 각각 처리한 시료에서 가장 낮은 수준을 보였다. 이로써 신선절단 사과의 갈변에 대한 한약재 추출물, 가열 및 코팅 처리의 억제 효과와 조건이 확인되었고, 이러한 방법은 화학물질을 부분적으로 대체할 수 있을 것으로 판단된다.

• 한국재료학회지
• /
• 제28권12호
• /
• pp.719-724
• /
• 2018

Cordierite composed of an alumina-silica-magnesia compound has a low coefficient of thermal expansion(CTE) and excellent thermal shock resistance. It also has a low dielectric constant and high electrical insulation. However, due to low mechanical strength, it is limited for use in a ceramic heater. In this study, $ZrO_2$ is added to an 80 wt% cordierite-20 wt% mullite composition, and the effect of $ZrO_2$ addition on the mechanical strength and thermal shock resistance is investigated. With an increasing addition of $ZrO_2$, cordierite-mullite formed $ZrO_2$, $ZrSiO_4$ and spinel phases. With sintering conducted at $1400^{\circ}C$ with the addition of 5 wt% $ZrO_2$ to 80 wt% cordierite-20 wt% mullite, the most dense microstructure forms along with an excellent mechanical strength with a 3-point flexural strength of 238MPa. When this composition is quenched in water at ${\Delta}T=400^{\circ}C$, the 3-point flexural strength is maintained. Moreover, when this composition is cooled from $800^{\circ}C$ to air, the 3-point flexural strength is maintained even after 100 cycles. In addition, the CTE is measured as $3.00{\times}10^{-6}{\cdot}K^{-1}$ at $1000^{\circ}C$. Therefore, 80 wt% cordierite-20 wt% mullite with 5 wt% $ZrO_2$ is considered to be appropriate as material for a ceramic heater.

• Journal of Microbiology and Biotechnology
• /
• 제18권7호
• /
• pp.1207-1215
• /
• 2008

To investigate the occurrence and species diversity of mycobacteria in waters, surface water samples were collected monthly from the Han River and tap water samples at the terminal sites of the distribution system. Mycobacteria in each water sample were isolated by decontamination using cetylpyridinium chloride (CPC) and cultivation on Middlebrook 7H10 agar, and then identified by polymerase chain reaction-restriction fragment length polymorphism analysis (PRA) and sequencing of the 65-kDa heat-shock protein gene (hsp65 gene). Mycobacteria were detected in 59% of the surface water samples and 26% of the tap water samples. Over half of the 158 isolates could not be identified by hsp65 PRA and gene sequencing, and several identification discrepancies were observed between the two methods. The most frequently isolated species was Mycobacterium gordonae in surface water and M. lentiflavum in tap water. M. avium complex (MAC), the most important pathogen among environmental mycobacteria, was detected in the surface water samples but not found in the tap water samples. The result demonstrated that water is an important environmental source of mycobacteria and the combined application of hsp65 PRA and sequencing was more reliable than hsp65 PRA alone to accurately identify mycobacteria present in water.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2002년도 학술대회지
• /
• pp.675-678
• /
• 2002

In order to develop the water hammering cleaner system for removing scale and slime in inner metal or non-metal piping wall, the flow characteristics are investigated by numerical and experimental methods. The air bubbles in the piping systems as a shock wave are formed and transferred with the water flow in the piping. The governing equations are derived from making using of three-dimensional Wavier-Stokes equations with the standard $k-{\varepsilon}$ turbulence model and SIMPLE algorithm. Pressure distributions in the pipeline are calculated for different air supply pressures. Also, we prepared some experimental results of the pressure differences for various air supply times.

• 한국수산과학회지
• /
• 제40권4호
• /
• pp.226-233
• /
• 2007

Physiological responses of mullet Mugil haematocheilus to cold shock in winter were investigated. The experimental mullets were initially acclimated at $10.0^{\circ}C$ and then the water temperature was reduced to $-1.2^{\circ}C$ for cold shock experiment. The stress responses was monitored for nearly 50 hours. The parameters monitored include survival rate, plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), glucose (GLU), total protein (TP), electrolytes $(Na^+,\;K^+,\;Cl^-)$, cortisol and thyroid hormones $(TT_4,\;TT_3,\;FT_4\;and\;FT_3)$. With the exception of the TP and electrolytes, most parameters changed significantly during the cold shock. The survival rate did not change from $10^{\circ}C\;to\;-0.6^{\circ}C$, but decreased significantly below $-1.0^{\circ}C$, and was zero at $-1.2^{\circ}C$. The plasma AST and ALT concentrations increased remarkably from $2.5^{\circ}C\;to\;0.5^{\circ}C$ and from $2.5^{\circ}C\;to\;1.5^{\circ}C$, respectively, and then declined rapidly as the temperature decreased to $-1.2^{\circ}C$. The plasma GLU concentration did not change until -0.5'E, and then the concentration increased significantly at $-1.2^{\circ}C$. The plasma cortisol concentration increased remarkably from $2.5^{\circ}C\;to\;-0.5^{\circ}C$, and then declined at $-1.2^{\circ}C$. The plasma thyroid hormones showed two changes during the cold shock. Both plasma 74 concentrations increased remarkably from $2.5^{\circ}C$\;to\;0.5^{\circ}C$, then declined rapidly until $-1.2^{\circ}C$, while both plasma 73 concentrations decreased significantly from $10^{\circ}C\;to\;2.5^{\circ}C$, and then remained significantly lower than the concentration at $10^{\circ}C$.

• 대한환경공학회지
• /
• 제31권9호
• /
• pp.817-824
• /
• 2009

여과공정에서 수리적 충격부하로 인한 탁질누출을 방지하기 위하여, 여과지 유입량 변화에 대응하여 여과지 운영지수를 변화시키면서 여과수의 탁도 및 입자수를 고찰하였다. S 정수장은 여과지 유입량 최대/최소의 비가 2.2였으며, 이에 따라 여과속도도 변동하였다. S 정수장에서는 여과속도 변동 최소화를 위하여 여과유입수량 변동에 따라 여과지수를 변동시켰다. 여과지 유입유량 변화에 따라 가동, 휴지, 재가동을 반복하였을 경우 탁질누출은 심하지 않았다. 여과가동 누계시간이 10 h 이전이나 50 h 이후에 재가동시는 탁질누출현상이 일부 발견되었다. 이런 현상은 여재의 숙성이 충분하지 않거나 입자물질의 부착량 과다에 기인할 수 있다. 따라서 여과지를 재가동할 때는 누계여과지속시간이 10 h 이상, 50 h 미만인 여과지를 선택하는 것이 효율적인 것으로 조사되었다. 여과지 유입유량 변동에 따른 여과지수 변동은 UFRV 향상을 위한 방법으로 판단된다.

• 한국유체기계학회 논문집
• /
• 제12권5호
• /
• pp.19-24
• /
• 2009

This paper is performed to find out the stability of water-hammer in pipe line and pump station that is happened when additional water needs demanded. At first, the water supply construction project is planned to supply $6,000\;m^3/day$ through 17.9 km pipe line. But additional demand ($1,200\;m^3/day$) happened from Cheong-ra water reservoir. In this situation, air-chamber($4\;m^3$) and vacuum breaker valve(${\varphi}100\;mm$) are needed to prevent water-hammer. When the additional water is supplied, the existing facilities (air-chamber, vacuum breaker valve) are sufficient to alleviate shock not changing capacity alteration, judging from the airspace change and rise. Therefore, there is no problem for water-hammer by installing air-chamber($4\;m^3$) and vacuum breaker valve(${\varphi}100\;mm$) at the top of Yeo-ju hill.

• 생명과학회지
• /
• 제28권6호
• /
• pp.639-647
• /
• 2018

한국의 고급 양식대상 어종인 붉바리(Epinephelus akaara)로부터 새로운 heat shock protein (Hsp) 70을 동정하였다. 붉바리 Hsp70 (RgHsp70)의 cDNA는 RACE (rapid amplification of cDNA ends)법을 사용하였고, RgHsp70 cDNA의 전장은 2,152 bp이고, 5'-terminal untranslated region (UTR)은 105 bp, 3'-terminal UTR은 274 bp, 590개의 아미노산을 암호화하는 open reading frame (ORF)는 1,773 bp였으며, 분자무게(molecular weight)는 64.9 kDa 및 등전위값(isoelectric point, pI)은 5.2였다. 추정되는 아미노산 비교 및 계통발생학적 분석 결과, 다른 어종과 마찬가지로 Hsp70 고유의 signature를 포함하는 것을 비롯하여 높은 유사성을 나타내었으므로 RgHsp70이 Hsp70 family임을 확인할 수 있었다 RgHsp70 mRNA는 간과 두신 조직에서 높은 발현을 보였으며, 48시간 동안 수온별(21, 18, 15 및 $12^{\circ}C$) 노출 후 간 조직에서 대조구인 $21^{\circ}C$보다 $12^{\circ}C$에서 발현이 증가함을 확인하였다. 본 연구에서는, 수온이 하강함에 따라 RgHsp70 mRNA 발현에 주요한 영향을 미치는 것으로 보아, 수온변화에 따른 스트레스로 인해 발현의 변화를 나타내는 주요 스트레스성 단백질임을 확인할 수 있었다.

• 한국물환경학회지
• /
• 제26권1호
• /
• pp.44-51
• /
• 2010

A lab-scale apparatus for turbid water transport control was tested and examined. The channel had a dimension of $100cm{\times}30cm{\times}15cm$ (length${\times}$hight${\times}$width). And the turbidity water was prepared using two types of particles, bentonite and loess. The channel equipped with filamentous mat was operated under various shock load conditions. In the control channel, instantly, turbid water mixed with the clean water inside the channel and turbidity prevails the entire channel. While in the mat-equipped channel, it increases only at the bottom. Overall, the filamentous mat gave capture efficiency of 70~90% compared with the control group. The capture efficiency of turbid particles decreased with increased input turbidity flux. The result of experimental run on how turbid particles are separated in the mat channel shows that settling, filtration and attachment are the main processes. Meanwhile, turbidity was diffused from the channel bottom due to turbidity gradient before and after mat zone. The particle size before mat zone was lightly coarser than that after mat zone.