• 수산해양기술연구
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• 제39권1호
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• pp.56-62
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• 2003

서해 연근해에서 사용하고 있는 기타 통발의 주 어획대상이 되고 있는 꽃게 및 피뿔고둥과 혼획율이 비교적 높은 쥐노래미를 대상으로 수조실험을 통하여 통발의 사용 경과기간에 따른 입롱행동을 조사하기 위하여 실제 어업 현장에서 사용하고 있는 통발 중에서 사용 경과기간이 서로 다른 세 종류의 통발(새 통발, 6개월 사용한 통발 및 12개월 사용한 통발)을 선별하여 각각의 통발에 대한 입롱율을 조사하고, 통발의 망목선택성을 추정하기 위한 기초자료를 얻기 위하여 꽃게나 피뿔고둥에 비해 활동성이 높은 쥐노래미에 대하여 세 종류의 망목(망목 35mm, 50mm 및 65mm)의 통발에 대한 입롱행동을 각각 조사한 결과는 다음과 같다. 1. 꽃게에 대한 통발의 사용 경과기간별 입롱율은 사용 경과기간이 6개월인 통발이 평균 4.4마리(44.0%)로서 가장 높았으며, 새 통발 2.8마리(평균 28.0%), 12개월 사용한 통발 평균 2.0마리(20.0%)의 순으로 나타났다. 2. 피뿔고둥에 대한 통발의 사용 경과기간별 입롱율은 새 통발이 평균 7.3마리(36.7%)로서 가장 높았으나, 6개월 사용한 통발이 평균 7.2마리(35.8%)로서 큰 차이가 없었으며, 12개월 사용한 통발이 평균 5.7마리(28.3%)로서 가장 낮았다. 3. 쥐노래미에 대한 통발의 사용 경과기간별 입롱율은 사용 경과기간이 6개월인 통발이 평균 3.4마리(34.0%)로서 가장 높았으며, 새 통발 평균 3.0마리(30.0%), 12개월 사용한 통발 평균 2.8마리(28.0%)의 순으로 나타났다. 4. 통발의 망목별 쥐노래미의 잔류율은 망목 35mm인 통발이 평균 2.4마리(24.0%)로서 가장 높았으며, 망목 50mm인 통발이 평균 2.2마리(22.0%), 망목 65mm인 통발이 평균 2.0마리(20.0%)의 순으로 나타났다.lly, I carried out calculation of sensitivity of control constants of autopilot with various conditions of ocean environments. 사별자의 개별성과 요구에 적합한 접근방법이 모색되어야 한다. 앞으로 한국실정에 맞는 토착화된 사별관리를 위한 다각적인 연구가 시도되어야 하며 이를 실무에 적용시켜야 한다.ssumption, additional study is needed to examine the relationship between the levels of microbes and excessive concentrations of EA, and borate at a high pH level.부정적인 반응을 보였다. '한국음식을 더 많이 해서 전통음식과 친밀한 장소로 발전시키자', '계절식품을 이용하고 비슷한 종류의 음식은 빼서 가격을 낮추자', '연령에 따라서, 또, 성인에서는 성별에 따라 가격 차이를 두자'는 의견 등이 있었다.이용한 배반포의 체외생산에 있어서 배양액내 항산화제의 첨가는 체외성숙단계에서만 효과적이었다. 이것은 아마도 항산화제가 체외성숙 시 난포란 내에서 일어나는 여러 가지 생화학 반응의 처리시간과 관련하여 활성화시킴으로써 난포란의 생존력을 높인 것이라고 사료되기 때문에 앞으로는 돼지 난포란의 효율적인 체외성숙에 대해서 배양액내 첨가물질은 물론 나아가서 방법론적인 측면에서 더욱 연구되어져야 할 것이다.ed from Nusselt's film condensation theory on tilted plate. Using those two expressions, a correlation was formulated as a function of heat flux and tilt angle,

• Membrane and Water Treatment
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• 제9권5호
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• pp.335-342
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• 2018

Micelle-Enhanced Ultrafiltration (MEUF) is a membrane separation processes that improving ultrafiltration process with the formation of micelles of the surface active agents. Surface active agents are widely used to improve membrane processes due to the ability to trap organic compounds and metals in the treatment of industrial waste water. In this study, surface active agents are used to improve micelle-enhanced ultrafiltration (MEUF) to reduce chemical oxygen demand (COD), total dissolved solid (TDS), turbidity and clogging the membrane in dairy wastewater treatment. Three important operational factors (anionic surface active agent concentration, pressure and pH) and these interactions were investigated by using response surface methodology (RSM) and Box-Behnken design. Results show that due to the concentration polarization layer and increase the number of Micelles; the anionic surface active agent concentration has a negative effect on the flux and has a positive effect on the elimination of contamination indices. pH, and the pressure have the greatest effect on flux. On the other hand, it could be stated that these percentages of separation are in the percentages range of Nano-filtration (NF). While MEUF process has higher flux than NF process. The results have been achieved at lower pressure while NF process needs high pressure, thus making MEUF is the replacement for the NF process.

• 한국수산과학회지
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• 제23권3호
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• pp.185-191
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• 1990

낙동강 하구호의 부영양화와 관련된 인의 순환과정을 구명하기 위해 낙동강 하구호에서 인의 침강과정에 대한 연구를 수행하였다. sediment trap에 포집된 침강성 물질의 침강 플럭스는 중층 및 저층에서 각각 $296g/m^2/d$, $955g/m^2/d$, 침강속도는 1.25m/hr, 3.31m/hr이었고, 인의 침강 플럭스는 중, 저층에서 각각 $0.64g/m^2/d$, $1.97g/m^2/d$, 침강속도는 0.85m/hr, 1.89m/hr이었다. 침강성 물질에 존재하는 POP의 총린에 대한 존재비율은 중층에서 $51.9\%$, 저층에서는 $48.3\%$로 나타났다. 이상의 결과에서 부영양화 모델을 낙동강 하구호에서 적용할 경우 기존의 인의 침강속도 가정치에 대한 보정이 반드시 행해져야 함을 알 수 있다.

• Ocean and Polar Research
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• 제33권spc3호
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• pp.385-395
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• 2011

Time-series sediment traps were deployed at 1,000 m water depth of the northwestern subtropical Pacific from July 2009 to June 2010, with the aim of understanding temporal and spatial variations of sinking-particle fluxes. The opening and closing of the traps was synchronized at 18-day periods for 20 events. Total mass fluxes showed distinct seasonal variations with high values for the summer-fall seasons and relatively low values for winter-spring. This seasonal variation at two stations was characterized by a distinct difference in $CaCO_3$ fluxes between the two seasons. The enhanced $CaCO_3$ flux in the summer - fall seasons might be attributed to an increased planktonic foraminiferal flux. Total mass flux at FM10 station was nearly 50% higher than that at FM1 station. The difference in $CaCO_3$ fluxes between two stations contributed nearly 70% of the difference of total mass fluxes. The $CaCO_3$ flux was a major component controlling temporal and spatial variation of sinking - particle fluxes in the western subtropical Pacific Ocean.

• Ocean and Polar Research
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• 제24권2호
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• pp.123-134
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• 2002

Seasonal variations of settling particles and metal fluxes were monitored at a nearshore site of Marian Cove, King Geroge Island, Antarctica from 28th February 1998 to 22nd January 2000. Near-bottom sediment traps were deployed at 30m water depth of the cove, and sampling bottles were recovered every month by SCUBA divers. Total particulate flux and metal concentrations were determined from the samples. Total particulate flux showed a distinct seasonality, high in austral summer and low in austral winter: the highest flux $(21.97g\;m^{-2}d^{-1})$ was found in February of 1999, and the lowest $(2.47g\;m^{-2}d^{-1})$ in September of 1998, when sea surface was frozen completely. Lithogenic particle flux accounted for 90% of the total flux, and showed a significantly negative correlation with the thickness of snow accumulation around the study site. It was suggested that the most of the lithogenic particles trapped in the bottles was transported by melt water stream from the surrounding land. Fluxes of Al, Fe, Ti, Mn, Zn, Cii, Co, Ni, Cr, Cd, and Pb showed similar seasonal variations with the total flux, and their averaged fluxes were 34000, 9000,960, 180, 13.8, 17.6, 3.0,2.1, 5.4, 0.02, and $1.5nmol\;m^{-2}d^{-1}$ respectively. Among the metals, Cu and Cd showed the most noticeable seasonal patterns. The Cd flux correlated positively with the fluxes of biogenic components while the Cu flux correlated with both the lithogenic and biogenic particle fluxes. The Cu flux peak in the late summer is likely related to a substantial amount of inflow of ice melt water laden with Cu-enriched lithogenic particles. On the other hands, the Cd flux peak in the early spring may be associated with the unusually early occurred phytoplankton bloom.

• 한국제4기학회지
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• 제13권1호
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• pp.91-98
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• 1999

부유성 유공충의 상대적인 양이 고기후 및 고해양환경의 해석에 미치는 영향을 1년 동안 관찰한 퇴적물 포집장치에 함유된 유공충의 연구로 행하여졌다. 본 연구는 저자들이 알고 있는 한 처음으로 행해진 것이다. 총 부유성 유공충의 수, 고기후의 지시자로 사용되는 부유성 유공충 G. bulliodes와 N. dutertrei)의 상대적인 양, 수온, 염도 등은 부유성 유공충 유생의 상대적인 양과 통계적으로 의미 있는 상관관계를 보이지 않는다. 하지만 부유성 유공충 유생의 상대적인 양은 종다양성지수(종 풍성도, 샤논-와이너 지수, 균등도)와 상관관계를 보인다. 이러한 결과는 유생의 양은 종의 상대적인 양에는 영향을 미치지 않으나 종다양성에는 영향을 미침을 의미한다. 따라서 퇴적물 포집장치에서 일년간 관찰한 결과에 의하면 부유성 유공충의 유생을 count 시 제외했을 때 종다양성 지수를 이용한 고기후/고환경해석시 주의 가 요망된다.

• Nuclear Engineering and Technology
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• 제46권4호
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• pp.513-520
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• 2014

In this paper, three types of operational and industrial absorbers used at research reactors, including Ag-In-Cd alloy, $B_4C$, and Hf are selected for sensitivity analyses. Their integral effects on the main neutronic core parameters important to safety issues are investigated. These parameters are core excess reactivity, shutdown margin, total reactivity worth of control rods, thermal neutron flux, power density distribution, and Power Peaking Factor (PPF). The IAEA 10 MW benchmark core is selected as the case study to verify calculations. A two-dimensional, three-group diffusion model is selected for core calculations. The well-known WIMS-D4 and CITATION reactor codes are used to carry out these calculations. It is found that the largest shutdown margin is gained using the $B_4C$; also the lowest PPF is gained using the Ag-In-Cd alloy. The maximum point power densities belong to the inside fuel regions surrounding the central flux trap (irradiation position), surrounded by control fuel elements, and the peripheral fuel elements beside the graphite reflectors. The greatest and least fluctuation of the point power densities are gained by using $B_4C$ and Ag-In-Cd alloy, respectively.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.51-59
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• 2000

The purpose of the present study is to investigate the absorbing characteristics in a vertical falling film type absorber using LiBr-H$H_2O$ solution as working fluids with the concentration of 60 wt%. The experimental apparatus consists of an absorber with the diameter of 17.2 mm and the length of 1150 mm, a generator, an evaporator (condenser), a weak solution tank and a sampling trap device and so on. The parameters were the solution temperatures of 45 and 50$^{\circ}$C, coolant temperatures of 30 and 35$^{\circ}$C, and the film Reynolds numbers from 50 to 150. The pressure drop in the absorber increased as the solution and coolant temperatures decreased. The pressure drop in the absorber increased up to the film Reynolds number of 90, however, decreased at the film Reynolds number above 90. The maximum absorption mass flux was observed at the film Reynolds number of 90. Absorption mass fluxes increased as the coolant temperature decreased. Accordingly, absorption mass fluxes and heat transfer coefficients under the subcooled condition increased more than those under the superheated condition. It is claimed that heat transfer coefficients are deeply affected by the solution temperature more than the coolant temperature within the experimental range.

• 설비공학논문집
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• 제11권6호
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• pp.835-845
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• 1999

The objective of the present study was to investigate heat and mass transfer characteristics in a vertical falling film type absorber using LiBr-$H_2O$ solution with 6owt%. The experimental apparatus consisted of an absorber with inner diameter of 17.2 mm and length of 1150mm, a generator, an evaporator/condenser, a solution tank, a sampling trap etc. The parameters were solution temperature of 45 and $50^{\circ}C$, coolant temperature of 30 and $35^{\circ}C$, and film Reynolds numbers from 50 to 150. Pressure drop in the absorber increased as solution and coolant temperatures decreased. Pressure drop in the absorber increased up to the film Reynolds number of 90, and then decreased at the further increase of the Reynolds number above 90. The maximum absorption mass flux observed at the film Reynolds number of 90. Absorption mass flukes increased as coolant temperature decreased. Absorption mass fluxes and heat transfer coefficients under subcooled condition were larger than those under superheated condition. Heat transfer coefficients were affected by solution temperature more than coolant temperature. The maximum absorption effectiveness under the subcooled condition was 23% for coolant temperature of $30^{\circ}C$ and 31% for coolant temperature of $35^{\circ}C$ under the present experimental conditions.

• Membrane and Water Treatment
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• 제6권1호
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• pp.1-13
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• 2015

The modification of ultrafiltration membranes with carbon nanotube (CNT) buckypaper on fouling control was investigated. Two types of commercially available flat-sheet membranes were used: PS35 and PES900C/D (PES) (the PS35 membranes were hydrophilic with a molecular weight cutoff of 20 kDa, and the PES membranes were hydrophobic with a molecular weight cutoff of 20 kDa). The CNT buckypaper modified ultrafiltration membranes were prepared by filtering a CNT suspension through the flat-sheet membrane in a dead-end ultrafiltration unit. After modification, the pure water flux of PES was significantly increased, while the pure water flux of PS35 was decreased. The properties of the CNT modified membranes were also investigated. Considering the antifouling properties, pure water flux of the modified membrane, and the stability of CNT buckypaper layer on the membrane surface, ethanol solution with a concentration of 50 wt.%, multi-walled carbon nanotubes (MWCNTs) with a larger diameter (30-50 nm), and the CNT loading with $7.5g/m^2$ was selected. The CNT buckypaper on the surface of ultrafiltration membranes can trap the pollutants in sewage effluent and prevent them reaching the surface of virgin membranes. Water quality analysis showed that the effluent quality of the modified membrane was obviously improved. The removal efficiency of humic acid and protein-like matters by the modified membrane was significant. These results indicate the potential application of the CNT buckypaper layer modified membranes in the field of wastewater reclaim.