• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.2
• /
• pp.94-98
• /
• 2004

• Journal of Korean Society of Water and Wastewater
• /
• v.16 no.6
• /
• pp.717-725
• /
• 2002

A bench-scale submerged-type membrane filtration system (SMFS) was constructed to study a feasibility of membrane filtration for solid-liquid separation in water and wastewater treatment processes. In the case of applying the SMFS to a biological wastewater treatment process, so-called membrane bioreactor, aeration underneath membrane modules is usually employed in order to provide oxygen demand for microbial growth as well as to control membrane fouling. A study was investigated the effects of operation parameters by aeration intensity, feed concentration, foulant type and airlift pore size on critical flux. Critical flux tends to increase with aeration rate. Optimal aeration flow rate was found to be 10 L/min/module. Feed concentration and foulant type has a significant effect on membrane fouling and filtration performance. But downward position and pore size of airlift has no a significant effects on membrane fouling and filtration performance.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2021.07a
• /
• pp.293-294
• /
• 2021

본 연구는 어업에 종사하는 어업인을 대상으로 작업복 착용실태와 불편사항 및 문제점, 작업복에서 요구되는 기능 등을 알아보고 이를 통해 어업에 적합하고 작업 효율성을 높일 수 있는 기능적 작업복 개발에 필요한 요구사항을 파악하고자 하였다. 본 연구는 전남지역의 어업인 124명을 대상으로 하였다. 분석은 SPSS 26.0 프로그램을 활용하였다. 본 연구에 참여한 어업인은 50대가 가장 많았고 남성이 약 85%이며, 근무경력은 10년 이상 20년 미만이 많았다. 작업복은 상하 분리형을 좋아하며, 방수성을 가장 중요하게 생각하였다. 착용 작업복에 대한 만족도는 땀투과성을 제외한 모든 항목에서 보통으로 평가되었다. 선호하는 색상은 무채색이 가장 많고 상하 분리형 스타일과 지퍼 여밈을 좋아하였다. 연령에 따라 작업복 구입 시 고려사항에 유의미한 차이를 나타내 30대 이하와 40대는 활동성을, 50대는 내구성을, 60대는 방수성을 가장 중요하게 생각하였다. 연령에 따른 작업복 만족도는 활동성, 압박감, 탈착성, 맞음새, 두께감, 기능성, 보온성, 옷의 무게감 등에서 유의미한 차이를 나타냈다. 본 연구를 바탕으로 하여 실용적이고 기능적인 어업용 작업복 개발이 이루어져야 할 것으로 생각된다.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.26 no.3
• /
• pp.169-175
• /
• 2016

There are many researches to develop robots that improve its mobility and task planning to adapt in various uneven environments. In this paper, we propose the design method and task planning of quadruped robot which can have top-bottom docking structure. The proposed quadruped robot is designed to adjust leg length using linear actuators and perform top-bottom docking and undocking using octagonal cone shaped docking module. Also, to stable walking and information gathering in the various environments, a geomagnetic sensor, PSD sensor, LRF sensor and camera. We propose an obstacle avoidance method and the topbottom docking algorithm of the two quadruped robots using linear actuator. The robot can overcome obstacles using adjusting leg length and activate the top-bottom docking function. The top-bottom docking robots of two quadruped robot can walk 4 legged walking and 6 legged walking, and use 4 arms or 2 arms the upper. We verified that the docking robots can carry objects using 4 leg of the upper robot.

• 한국해양학회지
• /
• v.28 no.1
• /
• pp.17-23
• /
• 1993

A right cylindrical tank with sloping bottom and top (${\beta}-effect$) is filled with two-layered fluid and is put on the rotating table. External fluid of same density as the lower-layer fluid is continuously injected to drive the lower-layer current. By minimizing the interfacial stress between two layers the motion in the lower-layer deformed the shape of interface such that the upper-layer adjust itself to the variations of the interface in terms of its direction of flow patterns .The most significant parameter is the internal Froude Number($F_1$) and when $F_1$ is greater than 6 two-cellular circulation of the upper-layer changes its direction, there by creates a separation of Western boundary current. The separation position moves to the most northward when $F_1$ equals to 6.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.26 no.6
• /
• pp.811-820
• /
• 2002

The physical responses and subjective sensations of different cleanroom garments were compared in order to discover which cleanroom garment design could minimize pollution of the working environment by dust from the worker, maintain a pleasant microclimate and provide effective thermoregulation. A. Coverall with non-detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice B. Coverall with detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice C. Separate top with non-detachable hood, kimono sleeves (front), raglan sleeves (back), raschell net on the bodice D. Coverall with non-detachable hood, set-in sleeves, raschell net on the bodice E. Coverall with non-detachable hood, raglan sleeves (back), l00% cotton inner wear (upper body) The results of the experiment were as follows. Because the hood covered the shoulder and the chest areas, the chests temperature of the worker wearing garment E was quite higher than those wearing other garment designs. For fabric that has been coated in order to prevent dust, layered designs should be avoided in order to prevent skin temperature from rising. Compared with layers of underwear, it would be more effective to attach a see-through raschell net which clings to the body. Thermal sensations were also highest in garment E, reinforcing the finding that layered designs should be avoided. Through the experiment, it was found that a new material coverall with a non-detachable hood was effective in minimizing dust, suppressing skin temperature increases, maintaining a superior microclimate and providing pleasant subjective sensations.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.5
• /
• pp.619-627
• /
• 2004

Purposes of this study were to examine closely the extracellular polymeric substances (EPS) which was a membrane fouling contaminant, to control detected EPS by powdered activated carbon (PAC) dosage etc. and to evaluate the possibility of practical reuse facility. With high removal efficiency of general pollutants, when the PAC is added to MBR, improvement of removal efficiency of $COD_{cr}$, and color was expected and treated wastewater can be reused. It was judged that the correlation between EPS and membrane fouling was very high. Carbohydrate and DNA in the EPS were judged to be cause of membrane fouling. If EPS could be controled, not only membrane fouling would be decreased but also operation time would be extended. In experiment of powdered activated carbon (PAC), characteristics of the best PAC for membrane fouling control were the particle size of $7{\mu}m$, lodine Number of 1,050, surface area of peat of $1,150m^2/g$. In lab test, operation time of MBR by PAC dosage of 200mg/gVSS was longer than one of MBR by without PAC dosage. Because EPS, especially carbohydrate and DNA, was controled successfully by PAC, membrane fouling in MBR could be decreased.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.2
• /
• pp.93-104
• /
• 2020

As water resources are limited and legal regulations are strengthened, there is a growing need to reuse residuals in WTP(Water Treatment Plant). In this study, membrane filtration system was constructed and its operation method was studied for water quality stabilization and reuse of WTP residuals. The operation parameters were stable for 1 year and 6 months. Membrane fouling was identified as particulate pollution (activated carbon) and inorganic pollution (manganese). The membrane system was operated steadily with raw water of high concentration SS(Suspended solid) containing activated carbon because membrane fouling was reduced by the effect of End-Free type. In the case of inorganic contamination, dissolved manganese eluted by chemicals and acted as a membrane fouling source, and the operating conditions for minimizing membrane fouling. were confirmed by newly developing application methods and types of cleaning chemicals. Based on the results, design parameters for reducing manganese membrane fouling were derived.

• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.1
• /
• pp.1-9
• /
• 2015

A combined treatment system using multiple source water is becoming important as an alternative to conventional water supply for small-scale water systems. In this research, combined water treatment systems were investigated for simultaneous use of multi-source water including rainwater, ground water, river water, and reclaimed wastewater. A laboratory-scale system was developed to systematically compare various combinations of water treatment processes, including sand filtration, microfiltration (MF), granular activated carbon (GAC), and nanofiltration (NF). Results showed that the efficiency of combined water treatment systems was affected by the quality of feed waters. In addition, a simply approach based on the concept of linear combination was suggested to support a decision-making for the optimum water treatment systems with the consideration of final water quality.

• Journal of Korean Society of Water and Wastewater
• /
• v.28 no.2
• /
• pp.181-193
• /
• 2014

Various treatment system for residuals have applied to save water resources, but most of them were not be satisfied with legal standard consistently. In this study, submerged membrane treatment system was operated to treat water treatment plant residuals and operation parameters was evaluated. Result of this experiment, high concentration organic matters contributed to high increase Transmembrane pressure(TMP) of membrane system(from 0.05 bar to 0.35 bar). And backwash process was effective to stabilize membrane system operation. After Cleaning-In-Place(CIP), permeability was recovered about 100 % from first operation condition. Inorganic matters (Fe, Mn, Al, Ca, Mg) were not effective membrane filtration performance. The quality of residual treatment was satisfied with drinking water quality standard and a treated water from that system was suitable for water reuse.