• 한국수정란이식학회지
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• 제11권1호
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• pp.81-83
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• 1996

This study was carried out to investigate the effect of sperm concentration of 5ml maxi-straw on farrowing rate and number of pigs born alive per litter in deep frozen boar semen. We did not find out the effect of sperm concentration on post-thaw sperm motility and NAR acrosome. However, farrowing rate and number of pigs born alive per litter of 7. 5 x 10˚ /5ml and 10.0 x 10˚ /5m1 sperm concentrations were higher than those of 5. 0 /10˚ /5ml sperm concentration.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1816-1820
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• 2008

Indoor air quality in public transportation such as railway, subway and bus is hard to control because of spatial restrict and variation of passenger's number. On January 2007, The Ministry of Environment announced "the guideline of indoor air quality in public transportation" for the concentration managements of particulate matter and carbon dioxide. In this study, we measured the PM10 concentration inside the Mugunghwa-ho passenger cabin and outdoor air and counted passengers. By the statistical analysis using SigmaPlot 2001 and SPSS 13.0, we found that indoor PM10 concentration is significantly affected by outdoor air. It is suggested that the air quality of inflow to the passenger cabin for air exchange must be controlled to support the indoor environment comfortably.

• 한국해양공학회지
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• 제13권2호통권32호
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• pp.129-137
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• 1999

The time of the onset of double-diffusive convection in time-dependent, nonlinear concentration fields is investigated theoretically. The initially quiescent horizontal fluid layer with a uniform temperature gradient experiences a sudden concentration change from below, but its stable thermal stratification affects concentration effects in such way to invoke convective motion. The related stability analysis, including Soret effect, is conducted on the basis of the propagation theory. Under the linear stability theory the concentration penetration depth is used as a length scaling factor, and the similarity transform for the linearized perturbation equations. The newlly obtained stability equations are solved numerically. The resulting critical time to mark the onset of regular cells are obtained as a function of the thermal Rayleigh number, the solute Rayleigh number, and the Soret effect coefficient. For a certain value of the Soret effect coefficient, the stable thermal gradient promote double-diffusive convective motion.

• Computers and Concrete
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• 제29권3호
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• pp.201-207
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• 2022

The evaluation of velocity profile for large values of buoyancy parameter and Bioconvected Rayleigh number is examined. The non-linear problem has been tackled numerically by shooting technique. Nanofluid temperature and nanoparticle concentration slightly elevates for increasing values of thermophoresis coefficient. Thickness of thermal boundary layer is significantly increased with thermophoresis coefficient whereas thickness of concentration boundary layer is more slightly enhanced. The response of temperature and nanoparticles concentration is observed due to change in Brownian motion parameter. As Brownian motion parameter increased temperature distribution is slightly enhanced. The reverse behavior is observed in case of nanoparticles concentration. Comparison of numerical technique with the extant literature is made and an acceptable agreement is attained.

• 한국대기환경학회지
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• 제24권4호
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• pp.404-414
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• 2008

A Transient Differential Mobility Particle Spectrometer (TR-DMPS) with a short response time was recently developed to monitor high concentration of ultrafine particles emitted from vehicles. To investigate the availability of the TR-DMPS for monitoring transient roadside aerosols, the number size distribution of ultrafine particles was monitored at the Cheongnyangni roadside in Seoul on March 23, 2007 together with a Scanning Mobility Particle Sizer (SMPS). The roadside aerosols were monitored every 5 min and 0.1 sec by using the SMPS and the TR-DMPS, respectively. The concentration of ultrafine particles at the roadside was highly fluctuated for a short duration. From the comparison of particle number concentrations and size distributions between two instruments, it was confirmed that the SMPS provided fairly good time-averaged number size distribution although it did not follow rapid change of particle number concentration at the roadside. The TR-DMPS quickly responded to a rapid change of particle number concentration due to abrupt traffic flow. However, the TR-DMPS frequently showed electrical noise events, resulting in underestimated particle contamination. A more stable operation of the TR-DMPS is needed in application of roadside aerosol monitoring.

• 한국세라믹학회지
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• 제49권1호
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• pp.78-83
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• 2012

The electrophoretic deposition(EPD) of ZnO nano-sized colloids is investigated by changing the colloid number concentration, applied force, and deposition time. The change of the colloid size in a suspension was examined by the different colloid number concentrations (N = $3.98{\times}10^{15}$, N = $3.98{\times}10^{14}$, and N = $3.98{\times}10^{13}$) with an increase of the deposition time and applied forces. Deposition behavior was investigated by changing the applied fields (from DC 5 V to 50 V) and the deposition time (5 min to 25 min). The surface microstructures of the as-deposited films were investigated by SEM. The dried films were sintered from $850^{\circ}C$ to $1,050^{\circ}C$ for 2 h and then the microstructures were also explored by SEM. The agglomeration rate was enhanced by increasing the colloid number concentration of colloids. Colloid number concentration in a suspension must be rapidly decreased at higher values of the electric field. ZnO nano-sized colloids had the highest zeta potential value of over -28 mV in methanol. A homogeneous microstructure was obtained at colloid number concentration of N = $3.98{\times}10^{13}$, applied DC field of 5 V/cm and 15 min of deposition time at an electrode distance of 1.5 cm. Under these conditions, the deposited films were sintered at $850^{\circ}C$ and $1,050^{\circ}C$ for 2 h. The results show a typical pore-free surface morphology of a uniform thickness of 400 nm under these experimental conditions.

• 한국엔터테인먼트산업학회논문지
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• 제14권6호
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• pp.109-124
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• 2020

이 연구는 한국 영화시장에서의 집중화 현상을 고찰하기 위해 스크린 규모와 흥행, 그리고 국적을 중심으로 이를 분석했다. 분석대상은 2005년부터 2019년까지 15년 동안의 연도별 흥행 100위권 영화로, 총 1,500편이다. 분석결과 스크린수는 매년 꾸준히 증가하는 추세였고, 스크린 집중화는 높은 수준으로 나타났다. 흥행 100위 기준 스크린 집중도는 2005년의 12%에서 30% 이상으로 상승했으며, 흥행 10위 기준에서는 2005년 21%에서 큰 상승폭을 보이며 2014년 이후 매년 50% 이상을 차지했다. 개봉 스크린 규모가 증가하면서 멀티플렉스는 흥행유인력이 높은 영화에 보다 많은 스크린을 할당했다. 오랫동안 스크린 독과점에 대한 비판이 있어왔지만 멀티플렉스는 2011년과 2012년 이후 이를 더 심화시키면서 한 편의 영화가 전체 스크린의 60% 이상을 차지하고 개봉되는 상황을 발생시키고 있다. 멀티플렉스의 이런 방식은 흥행 100위권 영화의 시장 점유율을 95%까지 상승하게 하고 있다. 또한 멀티플렉스는 한국영화보다 할리우드 영화에 보다 더 많은 스크린을 할당하는 경향을 보여주었다. 흥행성과가 높은 100위권을 대상으로 한 분석에서 영화 국적은 한국과 미국으로 집중된 것으로 나타났다. 이를 제외한 18개 국가의 경우 공급 측면에서 9.3%만 차지했다. 영화의 국적별 소비를 살펴보면, 두 국가로의 집중화 현상은 더 강하게 나타났다. 공급 차원에서 90.7%를 차지하고 있지만 소비 측면에서 96.6%를 차지했다. 공급에서의 집중화 현상은 소비에서의 집중화 현상과 정적인 상관관계를 보여주었고, 소비 측면에서의 집중화가 공급 측면보다 조금 더 높게 나타났다. 한국 영화시장은 스크린의 증가가 공급과 소비의 집중화를 심화한 사례로 드러났다.

• 한국잠사곤충학회지
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• 제39권1호
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• pp.17-21
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• 1997

Oral application of fenoxycarb, O-ethyl N-(2-(4-phenoxyphenoxy)ethyl) carbamate, the commercial formulation Insegar, on the 1st day of the 3rd instar made no difference in the egg laying and the hatchability as compared to 750 grains for the number of eggs laid, 53 grains for the number of the resideual eggs unlaid, 749 grains for the number of fertirized eggs, 97% for the total hatchability, and 95% for the useful hatchability as in the control but on the first day of the 4th instar, the number of the remainder eggs in the ovary increased by 2.4 folds, and reduced number of the eggs laid, number of unfertilized eggs, the hatchabillity and useful hatchability by 39%, by 66%, by 68% and by 72%, respectively. When diluted Insegar was applied topically every other two days from the pupae to the moth at concentration of 10-6, 10-7, 10-8, 10-9, 10-10 the number of eggs laid, the number of the unfertilized eggs, the total hatchability and the useful hatchability were decreased. More severe decrease took place as concentration lowered and the earlier application.

• 대기
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• 제25권4호
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• pp.659-667
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• 2015

In this study, sensitivity of inflow wind speed and turbulent Schmidt number to pollutant dispersion in an urban street canyon is investigated, by comparing CFD-simulated results to wind-tunnel results. For this, we changed systematically inflow wind speed at the street-canyon height ($1.5{\sim}10.0m\;s^{-1}$ with the increment of $0.5m\;s^{-1}$) and turbulent Schmidt number (0.2~1.3 with interval of 0.1). Also, we performed numerical experiments under the conditions that turbulent Schmidt numbers selected with the magnitude of mean kinetic energy at each grid point were assigned in the street canyon. With the increase of the inflow wind speed, the model underestimated (overestimated) pollutant concentration in the upwind (downwind) side of the street canyon because of the increase of pollutant advection. This implies that, for more realistic reproduction of pollutant dispersion in urban street canyons, large (small) turbulent Schmidt number should be assigned for week (strong) inflow condition. In the cases of selectively assigned turbulent Schmidt number, mean bias remarkably decreased (maximum 60%) compared to the cases of constant turbulent Schmidt number assigned. At week (strong) inflow wind speed, root mean square error decreases as the area where turbulent Schmidt number is selectively assigned becomes large (small).

• 대한기계학회논문집B
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• 제33권4호
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• pp.235-241
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• 2009

Experimental studies on single-phase toroidal circulation loop(thermosyphon) have been performed in the present study with Ag-nanofluids as a working fluids. The present paper deals with an experimental study on the heat transfer behavior of single-phase toroidal loop. Toroidal loop charged with nanofluid has been constructed and a number of tests have been carried out. Different geometric parameter, e.g., orientation has been investigated. The tests were conducted employing two fluids: distilled water and Ag-nanofluid of various volume concentrations. The experiments at Rayleigh number from $10^5$ to $10^6$ showed a systematic and slight deterioration in natural convective heat transfer. It was observed that the deterioration due to the particle concentration was in the range of 5-10%. At a given particle concentration of 0.05%, abrupt decrease in the Nusselt number and the Raleigh number was observed. The present study with toroidal loop shows that the application of nanofluids for heat transfer intensification should not be decided only by the effective thermal conductivity with increasing particle concentration.