• Korean Journal of Environmental Biology
• /
• v.37 no.2
• /
• pp.136-143
• /
• 2019

This study investigates the effect of denitrified biofloc water on changes in the water quality parameters and the physiological characteristics of shrimps. Biofloc rearing water contains a large number of microorganisms and can rapidly stabilize the water quality and energy saving if reusable due to high water temperatures. Rearing water contain floating bacteria with both aerobic and anaerobic bacteria. Therefore, when the carbon source is added in limited air supply, the anaerobic state is activated and the denitrification process is possible. In this study, the denitrification water had the following properties: ammonia (6.9 mg L^-1), nitrite (0.3 mg L^-1), nitrate concentration (9.2 mg L^-1), high pH (8.42) and alkalinity (590 mg L^-1). The experimental group consisted of seawater (SW, control), a mixture of Seawater and denitrified biofloc water (DNW) in the ratio of 3:1, 1:1 and DNW only. All experiments were done in triplicate. As a result, the survival rate never changed even when 100% of the denitrification water was utilized. However, a body fluid analysis showed that creatine and BUN were increased due to index of stress and the tissue damage resulting from the high denitrified water content. Body fluid ions (Na⁺, K⁺, and Cl^-) significantly decreased as the denitrified water content increased. It was recommended that the denitrification water be mixed with a certain ratio (less than 50%) in the future as it may affect the osmotic pressure control in shrimps.

• Journal of the Korean Chemical Society
• /
• v.33 no.4
• /
• pp.337-342
• /
• 1989

Gasless combustion is a vigorous exothermic reaction ignited directly in solid mixture, similar to Thermit reaction. The gasless combustion synthesis has the advantages of rapid processing, energy saving, low processing cost, and high purity of products. The Ti$Si_x$(x = 0.6, 0.8, 1.0, 2.0) systems are prepared by the gasless combustion synthesis without external sintering process. The crystallographic structures of $Ti_5Si_3$, $Ti_5Si_4$ are hexagonal and tetragonal system, respectively. Those of TiSi, $TiSi_2$ are orthorhombic systems. The results of X-ray analysis agree with the JCPDS data. The combustion modes of all combustion reactions are steady state combustions, and the propagation velocities of the combustion waves of $Ti_5Si_3$, $Ti_5Si_4$ and TiSi are greater than 0.6 cm/sec and that of $TiSi_2$ is 0.28 cm/sec.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.470-470
• /
• 2011

환경부 하수재이용사업은 2007년도 하수도법 개정을 통해 공공하수처리시설 처리수의 재이용 의무화를 시작으로 2010년도 "물의 재이용 촉진 및 지원에 관한 법률"의 시행으로 전국적으로 사업이 확대되고 있다. 제주도 월정하수처리장은 2009년도 하수재이용사업지구로 선정이 되어 2010년도부터 농업용목적의 재이용으로 구체적인 설계와 시공이 추진되고 있는 사업지구이다. 제주도에서는 지하수보존을 위해 대체수자원 개발 방안을 시급히 마련중에 있다. 특히, 제주도 농업용수 종합계획수립(제주도, 2004)에는 하수처리수를 농업용수로 이용하기 위한 계획을 수립할 정도로 지하수 사용량을 줄이기 위한 노력을 진행중에 있으며, 그 일환으로 하수재이용사업을 지속적으로 추진하고 있다. 하수처리수의 농업용수 재이용은 사용된 물을 재이용함으로써 물과 에너지를 절약할 수 있고, 유역 또는 해양으로 배출되는 오염원을 억제하는 장점이 있는 반면에 농산물 생육에 직접 영향을 줄뿐만 아니라 주변의 수질 생태 토양 환경 및 영농인의 보건에도 영향을 주기 때문에 장기적인 관찰과 검증작업이 필요하다. 이 에 서울대와 한국농어촌공사는 안전한 농업용수 재이용기술을 개발하기 위해 장기간 현장시험을 통해 재이용 재배기술과 함께 보건환경에 미치는 영향을 검증하였고 그 개발기술을 월정사업지구에 적용하게 되었다. 월정하수처리장이 위치한 제주 동부의 월정지역은 농지면적이 밭(374ha)과 과수(12ha)등 제주도의 전형적인 농촌마을으로 주요 재배작물은 마늘과 당근, 쪽파, 콩 등으로서 농업기반시설의 미비로 영농에 어려움을 호소하고 있으며, 2006년도에 발생한 가뭄으로 그 해 평균 수학량의 30%가 감소된 바 있는 지역이다. 제주도 농업용수 종합계획수립(2004, 제주도)에서는 10년에 한발을 기준 으로 $43,000m^3$/일의 용수가 부족할 것으로 분석하였으며 최근 $35,000m^3$/day 규모의 상수도 확보사업 계획 수립하였으나 여전히 농업용수가 부족하다. 방류수의 수질은 방류수수질기준을 만족하지만 염분함량이 높아 직접 농업용으로 사용하기에는 적당하기 않고, 농업용재이용방류수 수질기준에 맞도록 재이용시스템을 통해 재처리하여 농업용수로 사용해야 한다. 제주도에서는 이미 제주 서부하수처리장 농업용수 재이용사업(이하 판포재이용사업)'이 완료되어 재이용수를 농업용수로 공급하고 있으며 향후 지속적으로 하수재이용사업이 확대될 것으로 판단된다.

• Applied Chemistry for Engineering
• /
• v.25 no.4
• /
• pp.401-408
• /
• 2014

In membrane bio-reactor (MBR), the aeration control is one of the important independent variables to decrease fouling and to save energy with shear stress change on the membrane surface. The paper was carried out for numerical simulation of 3-dimensional fluid flow phenomena of the cylindrical bioreactor with submerged flat membranes equipped in the center and supplied the air from the bottom by using the COMSOL program. The viscosity and temperature of solution were assumed to be constant, and the specific air demand based on permeate volume ($SAD_p$) defined as scouring air per permeate rates was used as a variable. The calculated CFD velocities were compared with those of the velocity meter measurement and video image analysis, respectively. The results were good agreement each other within 11% error. For fluid flow in the reactor the liquid velocity increased rapidly between the air diffuser and membrane module, but the velocity decreased during flowing of the membrane module. Also, the velocity increased as it was near from the reactor wall to the central axis. The calculated shear stress on the membrane surface showed the highest value at the center part of the module bottom side and increased as aeration rate increased. Especially, the wall shear stress increased dramatically as the aeration rate increased from 0.15 to 0.25 L/min.

• Fashion & Textile Research Journal
• /
• v.1 no.2
• /
• pp.173-181
• /
• 1999

The purpose of this study was to investigate actual sleeping environments in Ondol rooms depending on the season. The experiment was performed on five healthy women. The bedroom environments using Ondol were measured in five cases (three apartments and two houses). The environments in bedroom, bedding temperature, skin temperature and thermal sensation were measured continuously through the seven days for each season in real life. This data of sleeping environments were analyzed in the view of seasonal variations and housing types. Annual average bedroom temperatures: $26.2{\sim}31.0^{\circ}C$ in apartments, $15.7{\sim}33.6^{\circ}C$ in houses. Annual average bedroom humidity: 48.3~82.1% RH in apartments, 64.9~87.0% RH in houses. During sleeping, temperatures of contact surfaces like sheets and under quilts ranged between $30.5^{\circ}C$ and $34.1^{\circ}C$ regardless of season or housing type. Annual average rectal temperature was $36.8^{\circ}C$ with no significant difference in season or housing type. In the point of thermal sensation, neutral temperature of the bedroom was $25.9^{\circ}C$ in apartments and $20.3^{\circ}C$ in houses. It was concluded that in spite of thermal environmental variations according to the seasons, skin, bedding and bedroom temperatures in apartments were better and more stable than those of houses. It is regarded that while houses are brick structured, apartments are steel-frame structured. Due to better insulation and air tightness, apartments were affected less from outdoor temperature and maintained higher room temperature than houses.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.11
• /
• pp.2083-2090
• /
• 2008

In this paper, we propose a method for control of temperature and the direction of wind in an air-cooler using thermal images and fuzzy inference rules in order to achieve energy saving. In a simulation for controlling temperature, a thermal image is transformed to a color distribution image of $300{\times}400$ size to analyze the thermal image. A color distribution image is composed of R, G and B values haying temperature values of Red, Magenta, Yellow, Green, Cyan and Blue. Each color has a temperature value from $24.0^{\circ}C$ to $27.0^{\circ}C$ and a color distribution image is classified into height hierarchies from level 1 to level 10. The classified hierarchies have their peculiar color distributions and temperature values are assigned to each level by temperature values of the peculiar colors. The process for controlling overall balance of temperature and the direction of wind in an indoor space is as follows. Fuzzy membership functions are designed by the direction of wind, duration time, and temperature and height values of a color distribution image to calculate the strength of wind. After then, the strength of wind is calculated by membership values of membership functions.

• The Journal of the Korea Contents Association
• /
• v.22 no.2
• /
• pp.147-161
• /
• 2022

This study examined changes in the ecological characteristics and design characteristics of Ban's exhibition space in three representative temporary exhibition halls and three permanent exhibition halls designed by Ban Shigeru since 2000. Through the investigation of the concepts and characteristics of ecological architecture, the design characteristics of exhibition space, the analysis framework of the design characteristics of exhibition space and the design elements of ecological architecture is obtained. The analysis results show that there are big changes between the temporary exhibition space and the permanent exhibition space in terms of building scale, space composition, function, materials and technology. On the one hand, the temporary exhibition space used recyclable materials, such as paper tubes, containers to be assembled on site into a single-layer space focused on display. The assembly method was simple and the construction period was short. After the exhibition, the exhibition space were dismantled. The materials were either transported to the next display site or recycled and reused. On the other hand, the permanent exhibition space used reinforced concrete as the main structure, and used a large amount of wood and glass materials to construct a multi-layered composite cultural space that separated the exhibition space and the leisure space. In terms of ecological characteristics, the building materials of the temporary exhibition space were recycled and no industrial wastes were generated after the demolition. The permanent exhibition hall uses eco-friendly wood for the roof and walls, so it is easy to replace and repair. Both types of exhibition halls are changing ecological architecture in a more sustainable direction by saving resources and energy through natural light and ventilation.

• Journal of Life Science
• /
• v.33 no.5
• /
• pp.436-444
• /
• 2023

Scientific training, diet, and ergogenic aids are widely used to overcome the limits of humans' physical abilities and to achieve excellent sports records. The adoption of nutritional strategies is important for athletes to perform at their highest level, and one of the main factors determining endurance ability is increased fat metabolism. A ketogenic diet (high fat, low carbohydrates) has thus been proposed as an alternative strategy to maximize fatty acid oxidation during prolonged periods of exercise. However, studies have shown mixed results regarding the ergogenic value of a ketogenic diet. For this reason, exogenous ketone supplements (EKS, ingestible forms of ketone bodies, ketone esters, and/or salts) have been suggested to obtain nutritional ketosis, an acute transient increase in circulating acetoacetate (AcAc) and b-hydroxybutyrate (bHB) concentrations, without limiting carbohydrate intake. Some studies have suggested the beneficial effects of EKS on the performance of endurance exercises by providing an additional fuel substrate for peripheral tissues, such as cardiac and skeletal muscles, sparing carbohydrates/increasing fat oxidation and post-exercise recovery by increasing glycogen resynthesis in the liver/muscle, attenuating protein degradation, stimulating protein synthesis in the skeletal muscle, etc. However, many studies have failed to observe the beneficial effects of EKS as an ergogenic aid. As such, this review summarizes the theoretical basis of, as well as the proposed and proven effects of EKS on exercise performance and recovery to date.

• Journal of Bio-Environment Control
• /
• v.18 no.1
• /
• pp.15-22
• /
• 2009

Adequate environment conditions with growth stage of potato were decided in a photoautotrophic micropropagation system using models. Total 20 day-period of growth were divided into three growth periods such as 6 (stage 1), 7(stage 2), and 7(stage 3) days. At the 1st stage, no significant differences were observed in the growth of potato plantlets at various photosynthetic photon flux density (PPFD) and $CO_2$ conditions. Considering damaged leaves, $80\;mmol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD and ambient $CO_2$ level were adequate in this stage. At the 2nd stage, significant differences were partly observed in several growth characteristics including dry weight. Based on the dry matter model, over $240\;mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD was too high to cultivate potato plantlets at this stage due to the occurrence of damaged leaves. Considering both plant growth and energy efficiency, $160\;mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD and $700\;mol{\cdot}mol^{-1}\;CO_2$ were selected for the adequate combination. At the 3rd stage, the biomass accumulation was significantly induced in potato plantlets under higher levels of PPFD and $CO_2$ concentration as suggested by increased fresh and dry weights. However, we could not find the saturated point with regard to dry matter due to continuous increase of dry mater even under maximum PPFD ($320\;mmol{\cdot}m^{-2}{\cdot}s^{-1})$. Thus, $320\;mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD and $1800\;mol{\cdot}mol^{-1}\;CO_2$ were considered as the best choice at final stage in this study. In conclusion, even though the growth period of micropropagated potato plantlets was quite a short, favorable environmental conditions required at each growth stage were different. This technique could improve the growth of micropropagated plantlets compared to the conventional micropropagation and apply to other agriculturally important crops as well as potato in the future.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.1
• /
• pp.305-316
• /
• 2013

To find out if modern roundabout is still effective under drivers behavior and driving conditions in Busan Metropolitan City, the effects before and after introduction of roundabout were analyzed. According to analysis on velocity profile at roundabout, velocity deviation decreased, and average vehicle speed was close to design speed. As a result, it has been confirmed that most roundabouts were properly built. In terms of traffic operation, average vehicle speed improved by 87.2% when a traffic intersection was replaced by a roundabout. therefore, it has been found out that the introduction of roundabout has a positive effect on increasing vehicle speed by reducing traffic congestion. In addition, annual benefits expected from the replacement from a traffic intersection to a roundabout were KRW 872 million as follows; KRW 410 million in traffic communication, KRW 39 million in transportation safety, KRW 255 million in energy saving, KRW 95 million in reduction of air pollution and KRW 73 million in reduction of traffic signal installation cost. In other words, if 10% (193 spots) of all traffic intersections (1,926 spots in total) in Busan City are replaced by roundabouts, the municipal authority would be able to save about KRW 168.3 billion. According to analysis on the benefits expected from the installation of roundabouts compared to the investment cost for traffic intersections, about KRW 679 million could be saved per roundabout. Considering 10% of all traffic intersections in the City of Busan, about KRW 131 billion could be saved annually. The traffic accidents in roundabout usually occur because drivers aren't aware of right-of-way rules. Once the right-of-way rules settle, the number of traffic accidents would significantly decrease. In addition, it is urgent to promote education and campaign for drivers, pedestrians and bikers on the roundabout.