• 대한환경공학회지
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• 제37권3호
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• pp.152-158
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• 2015

본 연구는 소수성 막 재질에 대한 막오염도를 평가하고자 수동흡착의 개념을 도입하여 정상운전을 위한 막 모듈 이외에 수동흡착 시험용 막 모듈을 설치하여 유출을 시키지 않은 상태에서 막 표면에 부착되는 미생물에 의한 막오염 정도를 분석함으로써 소수성 막오염 잠재성을 평가하고자 하였으며, 이때 운전조건으로 유기물 유입부하를 변화시켜 평가하였다. 이와 더불어 오염된 멤브레인을 세 가지 세정방법(두가지 물리적 세정과 화학적 세정)을 통해 막 세정 전후의 막오염 회복률을 평가하였다. 막오염 평가인자로는 반응조 내 MLSS 농도와 EPS 농도를 조사하였으며, 여과저항 값을 산정하여 막오염 전과 후, 세정 3단계 전과 후를 비교 평가하였다. 실험 결과로서, COD 농도가 750 mg/L인 가장 높은 부하량 조건에서 반응조 내 EPS 농도와 수동흡착 시험용 멤브레인의 여과저항 값이 가장 높게 나타났다. 또한 여과저항 값이 초기 운전 시작 후 차이를 보였지만 60일 이후의 최종 여과저항은 거의 일정하게 나타났는데, 이는 막 표면에 부착된 미생물량이 임계점에 이르러 수동흡착만으로는 더 이상의 막오염은 진행되지 않은 것으로 판단된다. PAds 상태에서 유기물 유입부하에 따른 오염된 막의 세정 전후의 여과저항 측정 결과에서는 3단계 세정 후 평균 회복률이 각각 Run 1이 78%, Run 2가 72%, Run 2가 69%로 유기물 부하가 높을수록 회복률이 떨어지는 것으로 나타났으며, 반면에 물리적 세정에 의한 복원률이 40일 경부터 Run 2와 Run 3의 물리적 세정에 의한 회복률이 낮아지는 것으로 보아 높은 유기물 부하로 인한 막표면의 케이크 형성으로 막오염이 심화된 것으로 판단된다.

• 대한기계학회논문집A
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• 제30권7호
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• pp.809-815
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• 2006

The temperature and loading-rate dependence on the mechanical behavior of single-walled carbon nanotubes under axial compression and torsion is examined with classical molecular dynamics simulation. The critical buckling is found to depend on the temperature and loading-rate. The yielding under torsion is also found to depend on the temperature and loading-rate. But it is shown that the compression and torsional stiffness are independent of the varied temperatures and loading-rates.

• 펄프종이기술
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• 제32권1호
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• pp.1-9
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• 2000

This study was carried out to improve the opacity of printing paper. Conventional filler loading enhanced the opacity of paper, but subsequently caused reduction of paper strength of paper. We try to seek a new filler loading method so-called beater loading that enhances opacity of paper as well as sustained desire strength. In our experiment, comparing to direct loading method, the beater loading method enhanced 0.8% of opacity and 0.2% of brightness. This also decreased the rates of strength reduction of paper. Therefore, the results obtained in this study indicated that beater loading was a very effective method to improve the opacity of paper while not to decreased so much of paper strength.

• 상하수도학회지
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• 제7권1호
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• pp.46-53
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• 1993

This study was carried out to examine substrate removal characteristics with the variation of the hydraulic retention time in an anaerobic filter. The feed concentration of synthetic wastewater used in the experiment was $10,000mg/l$ glucose. As media, the porosity of volcanic stones in Jeju island were 76%. The conditions of the experiment were as follows; HRT ranging from 1 day to 3 day, loading rates ranging from 3.33kg $COD_{er}/void\;m^3.day$ to 10kg $COD_{er}/void\;m^3.day$ and a temperature $35^{\circ}C$. Based on the results of the experiments, the COD removal efficiency was 98~99% in $COD_{er}$ method with loading rates ranging from 3.33kgCOD/void $m^3.day$ to 10kg COD/void $m^3.day$ and HRT ranging from 1day to 3 day. The produced quantity of gas equivalant to a porosity volume was $1.332~3.756Nm^3/void\;m^3.day$. The relationship between $COD_{er}$ loading rates and gas produced quantity equivalant to a porosity volume was well fitted with the equation of $Nm^3/void\;m^3.day{\cdot}=0.359L_0+0.179$($L_0=COD$ loading rate). Judging from the removal efficiency in this experiment, We concluded that anaerobic filter using Volcanic stones is one of improved and effective. As media, practical value of volcanic stones is sufficient.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2019년도 춘계학술대회
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• pp.310-312
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• 2019

4차 산업 혁명으로 인해 많은 기술들이 발전했다. 해당 기술들은 웹 표준 HTML5를 이용하여 웹을 통해 많은 사용자들에게 제공되고 있다. 웹에서 제공되는 콘텐츠가 증가함에 따라 웹을 이용하는 사용자의 수가 증가하였고 기존보다 더 웹 속도에 대한 중요성이 높아지고 있다. 왜냐하면 사용자들은 웹 페이지 로딩 속도가 빠르게 되는 것을 기대하고 있기 때문에 웹 페이지 로딩 속도가 증가되면 사용자들은 해당 페이지를 이탈하게 된다. 즉 웹 페이지 로딩 속도와 페이지 이탈률은 비례 관계에 있다. 따라서 콘텐츠를 제공하는 속도를 증가시켜 웹 페이지 로딩을 빠르게 할 필요가 있다. 본 논문에서는 웹을 통해 제공되는 콘텐츠 중 하나인 이미지에 관련하여 웹에서 이미지를 제공할 때 어떤 방식으로 제공하면 더 빠르게 제공될 수 있는지 실험을 통해 확인해보자고 한다. 해당 실험 결과를 바탕으로 웹을 통해 이미지를 제공하는 속도가 빠른 방법을 확인하고 해당 방법으로 이미지를 제공함으로써 페이지 이탈률을 낮추며 기존보다 더 사용자 친화적인 서비스를 제공하고자 한다.

• Structural Engineering and Mechanics
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• 제86권5호
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• pp.607-619
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• 2023

This study, it was tried to evaluate the asphalt behavior under tensile loading conditions through indirect Brazilian and direct tensile tests, experimentally and numerically. This paper is important from two points of view. The first one, a new test method was developed for the determination of the direct tensile strength of asphalt and its difference was obtained from the indirect test method. The second one, the effects of particle size and loading rate have been cleared on the tensile fracture mechanism. The experimental direct tensile strength of the asphalt specimens was measured in the laboratory using the compression-to-tensile load converting (CTLC) device. Some special types of asphalt specimens were prepared in the form of slabs with a central hole. The CTLC device is then equipped with this specimen and placed in the universal testing machine. Then, the direct tensile strength of asphalt specimens with different sizes of ingredients can be measured at different loading rates in the laboratory. The particle flow code (PFC) was used to numerically simulate the direct tensile strength test of asphalt samples. This numerical modeling technique is based on the versatile discrete element method (DEM). Three different particle diameters were chosen and were tested under three different loading rates. The results show that when the loading rate was 0.016 mm/sec, two tensile cracks were initiated from the left and right of the hole and propagated perpendicular to the loading axis till coalescence to the model boundary. When the loading rate was 0.032 mm/sec, two tensile cracks were initiated from the left and right of the hole and propagated perpendicular to the loading axis. The branching occurs in these cracks. This shows that the crack propagation is under quasi-static conditions. When the loading rate was 0.064 mm/sec, mixed tensile and shear cracks were initiated below the loading walls and branching occurred in these cracks. This shows that the crack propagation is under dynamic conditions. The loading rate increases and the tensile strength increases. Because all defects mobilized under a low loading rate and this led to decreasing the tensile strength. The experimental results for the direct tensile strengths of asphalt specimens of different ingredients were in good accordance with their corresponding results approximated by DEM software.

• Environmental Engineering Research
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• 제11권5호
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• pp.285-291
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• 2006

Biofiltration is a simple, effective, economically viable and the most widely used gas treatment technique for treating malodors at low concentrations and high flow rates. This paper reports the performance of two lab scale immobilized cell biofilters operated in continuous mode for hydrogen sulfide ($H_2S$) and ammonia ($NH_3$) removal. The removal efficiency (RE, %) and the elimination capacity (EC, $g/m^3{\cdot}hr$) profiles were monitored by subjecting the biofilters to different loading rates of $H_2S$ (0.3 to $8\;g/m^3{\cdot}hr$) and $NH_3$ (0.3 to $4.5\;g/m^3{\cdot}hr$). The removal efficiencies were greater than 99% when inlet loading rate to the biofilters were upto $6\;gH_2S/m^3{\cdot}hr$ and $4\;gNH_3/m^3{\cdot}hr$ respectively. The performance of the biofilters were also ascertained by conducting shock loading studies at a loading rate of $10\;gH_2S/m^3{\cdot}hr$ and $6\;gNH_3/m^3{\cdot}hr$. The results from this study show high removal efficiency, good recuperating potential and stability of the immobilized microbial consortia to transient shock loads.

• 한국물환경학회지
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• 제33권6호
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• pp.680-688
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• 2017

Water quality monitoring for flow rates and BOD/COD/T-N/T-P/SS/TOC concentrations has been conducted in Nakdong river tributaries since 2011. In this study concentrations and loading rates of BOD, T-P, and TOC were analyzed to evaluate water quality monitoring stations using accumulated data at 206 tributary monitoring stations in Nakdong river 2012 ~ 2016. Average concentration ranges for 206 monitoring stations were 0.3 ~ 6.4 mg/L, 0.025 ~ 1.562 mg/L, and 0.6 ~ 10.7 mg/L for BOD, T-P, and TOC, respectively. Additionally, average loading rate ranges were 0.96 ~ 46,040 kg/d, 0.087 ~ 1,834 kg/d, and 1.51 ~ 80,425 kg/d for BOD, T-P, and TOC, respectively. Average concentration for BOD, T-P, and TOC at each monitoring station was evaluated using ambient water quality standards of rivers and water quality regulation level for medium-sized management areas. Average loading rate and specific loading rate (loading rate/drainage basin area) for BOD, T-P, and TOC at each monitoring station was considered to evaluate monitoring stations using suggested classification (BOD, TOC: -1, 1 ~ 10, 10 ~ 100, 100 ~ 1,000, and 1,000 ~ kg/d; T-P: -0.1. 0.1 ~ 1, 1 ~ 10, 10 ~ 100, and 100 ~ kg/d) Using results of this study, various water quality status maps were provided, and three evaluation methods were suggested to determine priority monitoring stations in Nakdong river for rational water quality control and tributaries basin management.

• The Journal of Advanced Prosthodontics
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• 제4권1호
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• pp.18-23
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• 2012

PURPOSE. The purpose of this prospective study was to evaluate the effect of early loading on survival rate or clinical parameter of anodic oxidized implants during the 12- month postloading period. MATERIALS AND METHODS. Total 69 implants were placed in 42 patients. Anodic oxidized implants (GS II, Osstem Cor., Busan, Korea) placed on the posterior mandibles were divided into two groups, according to their prosthetic loading times: test group (2 to 6 weeks), and control group (3 to 4 months). The implant survival rates were determined during oneyear postloading period and analyzed by Kaplan-Meier method. The radiographic peri-implant bone loss and periodontal parameters were also evaluated and statistically analyzed by unpaired t-test. RESULTS. Total 69 implants were placed in 42 patients. The cumulative postloading implant survival rates were 88.89% in test group, compared to 100% in control group (P<.05). Periimplant marginal bone loss (T: $0.27{\pm}0.54$ mm, C: $0.40{\pm}0.55$ mm) and periodontal parameters showed no significant difference between the groups (P>.05). CONCLUSION. Within the limitation of the present study, implant survival was affected by early loading on the anodic oxidized implants placed on posterior mandibles during one-year follow-up. Early implant loading did not influence peri-implant marginal bone loss, and periodontal parameters.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.331-337
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• 2017

A simple strategy is proposed herein for attaining uniform current distribution in direct methanol fuel cells by varying the catalyst loading over the electrode. In order to use the same total catalyst amount for a serpentine flow field, three spatial variation types of catalyst loading were selected: enhancing the cathode catalyst loading (i) near the cathode outlet, (ii) near the cathode inlet, and (iii) near the lateral areas. These variations in catalyst loading are shown to improve the homogeneity of the current distribution, particularly at lower currents and lower air-flow rates. Among these three variations, increased loading near the lateral areas was shown to contribute most to achieving a homogenous current distribution. The mechanism underlying each catalyst loading variation method is different; very high catalyst-loading is shown to decrease the homogeneity of the distribution, which may be caused by water management in the thick catalyst layer thereof.