As aeration is an energy-intensive process, its control has become more important to save energy and to meet strict effluent limits. In this study, predictive aeration control based on the respirometric method has been applied to the sequencing batch reactor (SBR) process. The variation of the respiration rate by nitrification was great and obvious, so it could be a very useful parameter for the predictive aeration control. The maximum respiration rate due to nitrification was about 60 mg O2/L‧h and the maximum specific nitrification rate was about 7.5 mg N/g MLVSS‧h. The aeration time of the following cycle of the SBR was daily adjusted in proportion to that which was previously determined based on the sudden decrease of respiration rate at the end of nitrification in the respirometer. The aeration time required for nitrification could be effectively predicted and it was closely related to influent nitrogen loadings. By the predictive aeration control the aerobic period of the SBR has been optimized, and energy saving and enhanced nitrogen removal could be obtained.

PURPOSES : This paper aims to summarize the findings of studies related to driving safety in long tunnels, and based on these findings, evaluate the risk in driving safety in consecutive tunnels. METHODS: After evaluating the risk in consecutive tunnels, it was verified that driving safety depends on the tunnel length of the consecutive tunnels and the interval between the tunnels. The experimental devices used in this study were a virtual driving simulator and PolyG-I system, measuring, driving speed and among driver's brain waves, theta wave that represents drowsiness or inner conscious states. RESULTS: The results of experiment I showed that, in consecutive tunnels, the variation of speed was higher and the theta wave increased at similar points in comparison with that for long tunnels, demonstrating the risk in consecutive tunnels. The results of experiment II revealed that the variation of speed was the highest in the shortest tunnel (250 m) and the risk of overspeeding was the highest in the longest tunnel (900 m). Additionally, among the consecutive tunnels, the longer tunnels significantly increased the overall theta wave in the tunnels, increasing the risk of drowsy driving. CONCLUSIONS: Of the three scenarios, it was concluded that safety was highest when the tunnel length was set to 600 m.

반응-확산 모델을 이용한 연속적인 톤의 표현은 형태형성물질의 패턴 형성 방법을 이용한 기법이다. 그레이 스케일의 영상을 형태형성물질의 수학적 모델을 이용해서 이산적인 밝기를 가진 영상으로 변환할 수 있다. 이러한 방법은 영상을 점과 선의 형태로 변환할 수 있게 해주어 다양한 스타일의 영상 렌더링에 사용할 수 있다. 이는 영상의 밝기 정보가 형태형성물질로 변환되고 이를 통해 시뮬레이션을 했을 경우 예측 가능한 결과를 낸다는 가정에서 출발한다. 실제 실험에서는 대체적으로 급격히 변하지 않는 영상 신호에 대해서는 이러한 가정이 잘 들어맞기 때문에 좋은 결과를 나타내지만 영상 신호가 급격히 변화하는 부분에 대해서는 결과 영상에 문제(artifact)가 나타난다. 이는 밝기차이가 급격히 변하는 부분에서 검은 선 형태로 나타나며 이러한 부분은 원영상의 신호와 다른 결과를 낸다고 할 수 있다. 이를 해결하기 위해 본 논문에서는 반응-확산 모델에서 문제를 해결할 수 있는 방법을 도출하고 이를 적용한 새로운 계산 방법을 제시하여 문제를 해결하고자 한다. 제안된 방법에서는 밝기가 급격히 변화하는 부분을 검출하고 이러한 부분에서는 확산이 일어나지 않도록 제어함으로써 해결하였다.

본 연구에서는 역세척이 가능한 평막과 MBR 하부에서 공급되는 공기 및 자연적으로 순환되는 구형 입자를 이용하여 투과 실험하였다. 활성슬러지 수용액은 MLSS 8,000 mg/L로 유지하였으며 여과/이완(FR), 이완시 역세척(FR/BW), 사인파형 연속투과 운전(SFCO) 및 사인파형 연속투과 운전 시 역세척(SFCO/BW) 방식에 따른 막간차압(TMP)을 측정하였다. 역세척 유량을 47에서 14 L/m2⋅hr로 감소시키면, TMP가 증가하였으며 SFCO보다는 FR 방식의 TMP가 크게 증가하였다. 또한 역세척 방식이 구형입자를 이용한 세척방식보다 TMP를 더 감소시켰으며, 구형입자와 역세척 방식을 동시에 사용하면 각각의 방법보다 더 효과적임을 확인할 수 있었다.

Recent focus on wastewater treatment includes energy-saving and renewable energy generation for energy-independence of water infrastructures. Aeration and pumping in biological wastewater removal processes account for nearly 30-60% of the total electricity cost in real wastewater treatment plants. In this study, the performance and microbial characteristics were investigated in sequencing batch reactor under typical oxygen and oxygen limited condition. Under typical DO (7.55±0.99 mg/L) and low DO (0.23±0.08 mg/L) conditions, COD removal was stable over 91 % during SBR operation. Ammonia removal efficiency was reduced from 95.6 % to 89.2 % when DO concentration was dropped sharply. Phosphorus removal efficiency also reached 77% at oxygen-limited condition. The results indicated that removal efficiency both ammonia and phosphorus was influenced by DO condition. Microbial analysis revealed that Proteobacteria and Bacteroidetes at phylum level was dominant in typical DO and low DO conditions and DO concentration did not much affect phylum distribution. Population decrease of genera of nitrifying bacteria(Dokdonella) and Dechloromonas spp. affect removal efficiency of nitrogen and phosphorus at low DO condition.

The push-out tests have been conducted on the specimens which consist of the steel beam with U-shape section and the continuous cap-type shear connector. Existing formulas for the elevation of shear connector capacity were investigated on the basis of test results. The shear capacities of continuous cap-type shear connectors distinctly declined as the diameters of side-hole in the shear connector increased. The rebars through side-hole for the transverse reinforcement improved the shear capacity of continuous cap-type connector by 20 to 30 percent. It was not feasible to obtain the appropriate capacity values of continuous cap-type shear connectors made of thin steel plate like those of in this study, using the existing formulas. The new formula for reflecting the shear strength of penetrative bars was proposed based on the shear equation of Eurocode 4. The slip capacities of continuous cap-type shear connectors were shown to exceed the limit value of 6mm for the sufficiently ductile behavior.

범죄는 인적 또는 물적으로 피해를 일으키기 때문에 범죄가 발생한 이후에 조치를 취하는 것보다는 사전에 범죄를 예방하는 것이 중요하다. 또한, 범죄를 예방하기 위해서는 범죄발생에 취약한 지역을 추출해야 한다. 이에 본 연구에서는 범죄발생 위치정보 를 제공하지 않는 국내의 상황을 고려하여 실제 범죄정보를 직접적으로 사용하지 않으면서 시·공간적 특성을 고려한 범죄취약지역을 추출하는 연구를 수행하였다. 공간적인 특성정보는 연속수치지도에서 추출한 도로폭, 도로교차점, 도로교차각, 포장재질, 도로에 인접한 건물의 종류를 이용하여 범죄에 취약한 위험도로를 추출하였다. 또한 시간적인 특성정보는 점 형태로 제공되는 유동인구 데이터를 커널밀도 분석하여 추출하였다. 시·공간적인 분석을 위하여 두 가지 특성정보를 중첩 분석하여 범죄취약지역을 추출하였다. 취약지역을 검증하기 위해 다음포탈에서 제공하는 로드뷰 영상을 확인한 결과 추출된 취약지역이 노후화된 단독주택이 많고 도로주변이 잘 정비되지 않은 지역임을 알 수 있었다.

낙동강 하구에서 연속관측 자료를 바탕으로 담수의 방류와 수온 및 염분의 시간에 따른 반응을 조사하였다. 낙동강 하구 서쪽 해역에 계류형 센서를 설치하고 2017년 4월 1일부터 2018년 3월 31일까지 10분 간격으로 수온과 염분을 측정하였다. 담수의 방류량은 평상시에 200 m3 s-1 d-1 이하로 유지되었으나, 풍수기에는 500 ~ 1000 m3 s-1 d-1 이상의 많은 양의 담수가 빈번하게 방류되었다. 담수의 방류는 대조기에는 간조를 전후하여 발생하였고, 소조기 동안에는 계속적으로 일어났다. 평상시에 수온과 염분은 소조기 동안 큰 변동 없이 안정 되는 경향을 보이는 반면에, 대조기에는 방류주기에 따라 규칙적인 변동을 나타내었다. 연구기간 동안 염분은 평균 29이었으며, 평상시에 염분 농도는 평균 이상으로 유지되었고 일시적인 감소 이후에도 빠르게 회복되었다. 풍수기에는 약 3개월 동안 평균 이하의 저염환경이 지속되었다. 이러한 결과는 담수의 방류량뿐만 아니라 방류의 지속시간과 대량 방류의 빈도가 낙동강 하구의 표층 수온과 염분의 변동성에 영향을 미치는 중요한 요인이 된다는 것을 의미한다.

The respirometric technique has been used to analyze the nitrification process in a sequencing batch reactor(SBR) treating municipal wastewater. Especially the profile of the respiration rate very well expressed the reaction characteristics of nitrification. As the nitrification process required a significant amount of oxygen for nitrogen oxidation, the respiration rate due to nitrification was high. The maximum nitrification respiration rate, which was about 50 mg O2/L･h under the period of sufficient nitrification, was related directly to the nitrification reaction rate and showed the nitrifiers activity. The growth rate of nitrifiers is the most critical parameter in the design of the biological nutrient removal systems. On the basis of nitrification kinetics, the maximum specific growth rate of nitrifiers in the SBR was estimated as 0.91 d-1 at 20℃, and the active biomass of nitrifiers was calculated as 23 mg VSS/L and it was about 2% of total biomass.

Accompanied with the industrial development, and enlarging and heightening buildings, building equipments are also enlarging. These changes are serious to the cause of structure noises. The Floating Floor System which uses the soft foam polyurethane are becoming popular in construction areas for its short construction period and well vibration proof ability, hence it is becoming wide in the marketing volume. We were able to enhance the physical characteristics of the vibration proof polyurethane mat with this study. As a result, we were also able to secure material competitiveness by meeting the requirements of customer satisfaction through enhancement in estimated material lifetime and physical characteristics.

MBR(membrane bioreactor)공정은 운전시간이 지날수록 막 오염이 진행되면서 막간차압(TMP, transmembrane pressure)이 증가하고 결국 여과 성능이 감소하게 된다. 이러한 문제를 해결하기 위해 막 오염 제어에 대한 다양한 방식의 기술이 개발, 응용되고 있다. 본 연구에서는 경제적이고 효율적인 방법으로 막 오염을 제어하기 위하여 MBR 하부에서 공급되는 공기를 이용하여 자연적으로 순환되는 구형 비드와 역세척(backwashing)이 가능한 평막을 이용하여 사인파형 연속 투과운전(SFCO)방식에 따른 막간차압을 측정, 비교하고자 하였다.

In this paper, we analyze various types of racing lines and search for the optimum time to pass through the chicane, which are corners smaller than 90 degree. “Best” means the minimum time at maximum speed. This indicates that the inside and outside of the running line is not able to never win the internal between the connected lines. Even in the case of Chicane driving, the vehicle can accelerate at a high speed by increasing the turning radius near the straight line. In the study, the turning angle is inevitable if the angle is large because the turning angle is 44.3 because there is no straight running width. Therefore, by keeping the speed close to the straight line along the path of the incinerator, the speed of escape from the line can be shortened.

PURPOSES : The purpose of this study was to suggest a quantitative trend of the daily and seasonal cyclic movement of transverse crackwidth based on measurements in CRCP(Continuously Reinforced Concrete Pavement) within the first year of construction. METHODS : Crack gauges were installed in eight normal cracks, two induced cracks, and two construction joints of newly constructed CRCP. Crack width movements were continuously collected for about a year to investigate the cyclic behavior after construction. The daily and seasonal crack width movements were quantitatively analyzed and compared. RESULTS: Crack width movement in hot weather was relatively less than in cold weather. As a result of frequency analysis of the daily cyclic behavior, it was revealed by measurement that the minimum crack width from 2 p.m. to 4 p.m. was caused by expansion of the concrete; and that the maximum width from 6 a.m. to 8 a.m. was caused by contraction. Average crack width movements were calculated for every month and showed seasonal cyclic behavior. Maximum crack width was measured from December to January. Average crack width was investigated from March to April. Daily crack width movement in relation to concrete temperature was calculated from -0.00017 to -0.03844 mm/℃ and showed gradual decrease in absolute value with time caused by change in the crack spacing. It was found that the relationships between the monthly average crack width and concrete temperature are from -0.004 to -0.012 mm/℃. CONCLUSIONS : Crack-width movement shows a daily and seasonal cyclic behavior. Crack-width measurement in any time or season will have variance caused by daily and seasonal cyclic movement. Variances and trends were obtained in this study based on measurements for various cracks. The long-term behavior of cracks should be surveyed and compared with these measurements to investigate trends of convergence with time, caused by convergence of crack spacing.