광생물 반응기 설계를 위한 CFD 입자추적기술

제시비톡 ( Jessie P. Bitog ),이인복 ( In-bok Lee ) 한국농공학회 2011 한국농공학회 학술대회초록집 Vol.2011 No.-

Photobioreactors has been widely considered to be the most effective and efficient growth vessel for mass production of photosynthetic microorganisms such as microalgae for various purposes. However, practicable photobioreactor designs are still in the process of development. This can be observed from the rapid increase of numerical simulation studies on the design and development photobioreactors. Among the numerical methods, a computational fluid dynamic (CFD) technique holds the greatest potential considering its wide and practical application in multiphase flow systems. In this study, particle tracking technique of CFD was used to evaluate the performance of a 30L bubble type photobioreactor where the cells are considered as fine particles. The commercial CFD model Flow-3D was used in all tests. Flow-3D allows the release of particles from a user-defined source. A circular plane was defined as a source of particles in any part of the computational grid, with a given generation rate expressed in particles/second. The particles are passively transported by the flow and they do not interact with each other or with the fluid. The particles are assumed as spherical and defined by properties such as diameter and density. The locations of the particles were continuously tracked and the average amounts of light received by the particles were theoretically computed. The average growth of the cells was then computed based on the amount of light intensity distribution in the photobioreactor utilizing the Lambert-Beer Law proposed earlier by Lou and Al- Dahhan (2003). Results of the simulation study on growth of cells revealed good agreement with the growth of cells grown in a 30L photobioreactor.

축산 악취의 확산 예측을 위한 전산유체역학 모델의 개발

홍세운 ( Hong S. -w. ),이인복 ( Lee I. -b. ),황현섭 ( Hwang H. -s. ),( Jessie P. Bitog ),서일환 ( Yoo J. -i. ),유재인,권경석 ( Kwon K. -s. ),김용희 ( Kim Y. -h. ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-

Odor is one of the major nuisances in the environment. In most countries, odor annoyance from livestock production is an increasing problem in the community. In order to reduce the odor inconvenience and establish a good relation between livestock industries and the surrounding communities, many studies on the odor dispersion, such as diffusion simulations and field experiments have been investigated. Computational Fluid Dynamics (CFD) has been effectively and widely used to study this kind of research. CFD considers both various wind conditions as well as topographical conditions to study aerodynamic phenomenon. Therefore, the ultimate objective of the study was to develop an aerodynamic model to predict qualitatively and quantitatively odor diffusion from livestock. In this study, various phenomena and factors of odor diffusion from livestock houses were investigated from field experiments during the first year of this 3-years study. Later, those data will be also used to verify the CFD accuracy as well as to develop 3-dimensional CFD model.

전산유체역학 기법을 이용한 돈사 내 습식 공기 정화기의 적정 위치 설계

권경석,이인복,황현섭,홍세운,서일환,최지선,송상현,문운경,Kwon, Kyeong-Seok,Lee, In-Bok,Hwang, Hyun-Seob,Bitog, Jessie.P.,Hong, Se-Woon,Seo, Il-Hwan,Choi, Ji-Sun,Song, Sang-Hyeon,Moon, Oun-Kyung 한국농공학회 2010 한국농공학회논문집 Vol.52 No.3

In South Korea, as the living standard has been getting higher, meat consumption is steadily increasing. To meet the country's demand, livestock houses become larger and wider with increased raising density. In larger livestock houses, pollutants such as flake of pig skin, excrement, odor, various dusts and noxious gas like ammonia are excessively accumulated inside the facility. These will cause weak immunity for the pigs, diminution of productivity and degeneration of working condition. These problems can be solved through the ventilation performance of the facility. In the winter time, ventilation must be controlled to minimum to maintain a suitable thermal condition. However, this affects the other internal environmental condition because of the minimum ventilation. The installation of "wet air cleaner" especially in the winter time can be an alternative solution. For efficient application of this machine, there is a need to understand the existing ventilation condition and analyze the interaction of existing ventilation system with the wet air cleaner considering its appropriate location. In this study, the existing ventilation system as well as the internal environmental condition negatively inside the facility with the wet air cleaner has been studied using CFD technology. The CFD simulation model was validated from the study conducted by Seo et al. (2008). Results show that the elimination rate of ammonia was 39.4 % and stability could be improved to 35.1 % (Comparing case 5 to 1 where wet air cleaner machine was not used). It can therefore be concluded that case 5 shows the optimum location of a wet air cleaner in the livestock house.

돈사의 시설 및 환기구조에 따른 돼지 호흡기성 질병 발생 가능성

서일환 ( Seo I. -h. ),이인복 ( Lee I. -b. ),황현섭 ( Hwang H. -s. ),홍세운 ( Hong S. -w. ),( Jessie P. Bitog ),유재인 ( Yoo J. I. ),권경석 ( Kwon K. -s. ),김용희 ( Kim Y. -h. ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-

The typical diseases for pigs in Korea are Porcine epidemic diarrhea (PED), Porcine reproductive and respiratory syndrome (PRRS), Post weaning multi-systemic wasting syndrome (PMWS), and Porcine respiratory disease complex (PRDC). The main factor for the occurrence of these diseases specially the respiratory diseases is the environmental condition particularly ventilation inside the pig house. Considering that Korea has 4 distinct season, the environmental condition in the pig house changes every season. The purpose of this study was to find the relationship between the configuration of the structure and ventilation system of pig houses and the occurrence of pig respiratory disease. The effect of internal airflow distribution to internal disease dispersion in pig house was analyzed. Several field experiments were conducted at several pig farms to understand the environmental control in relation to disease occurrence. To overcome the difficulties of conducting field experiments and obtain internal airflow visualization quantitatively and qualitatively, computational fluid dynamic (CFD). The accuracy of the simulations was preliminarily examined and improvements were made in the model based form the seasonally collected farm data.

BES 프로그램을 이용한 국내 대표적 대형온실의 에너지 부하 예측

이성복,이인복,홍세운,서일환,권경석,하태환,한창평,Lee, Sung-Bok,Lee, In-Bok,Homg, Se-Woon,Seo, Il-Hwan,Bitog, P. Jessie,Kwon, Kyeong-Seok,Ha, Tae-Hwan,Han, Chang-Pyoung 한국농공학회 2012 한국농공학회논문집 Vol.54 No.3

Reliable estimation of energy load inside the greenhouse and the selection of cooling and heating facilities are very important preceding factors to save energy as well as initial and maintenance costs of operating a greenhouse. Recently, building energy simulation (BES) technique to simulate a model similar to the actual conditions through a variety of dynamic simulation methods, and predict and analyze the flow of energy is being actively introduced and developed. As a fundamental research to apply the BES technique which is mainly used for analysis of general buildings, to greenhouse, this research designed four types of naturally-ventilated greenhouses using one of commercial programs, TRNSYS, and then compared and analyzed their energy load properties, by applying meteorological data collected from six regions in Korea. When comparing the greenhouse load of each region depending on latitude and topographical characteristics through simulation, Chuncheon had nearly 9~49 % higher heating load per year than other regions, but its annual cooling load was the reverse to it. Except for Jeju, 1-2W type greenhouses in five regions showed about 17 % higher heating load than a widespan type greenhouse, and 1-2W type greenhouses in Chuncheon, Suwon, Cheongju, Daegu, Cheonju and Jeju had 23 %, 20 %, 17 %, 16 %, 18 % and 20 % higher cooling load respectively than a wide span-type one. Glasshouse and vinyl greenhouse showed 8~11 % and 10~12 % differences respectively in heating load, while 2~10 % and 7~10 % differences in cooling load respectively.

공기 중 바이러스 포집 장비의 효율성 평가

하태환,이인복,권경석,이성복,송상현,윤순식,Ha, Tae-Hwan,Lee, In-Bok,Kwon, Kyeong-Seok,Lee, Sung-Bok,Song, Sang-Hyeon,Bitog, Jessie. P.,Yoon, Soon-Seek 한국농공학회 2012 한국농공학회논문집 Vol.54 No.1

In livestock industry, damage caused by the epidemic diseases such as Foot-and-Mouth Disease (FMD), Highly-Pathogenic-Avian-Influenza (HPAI) and Porcine-Reproductive-and-Respiratory-Syndrome (PRRS) was very serious. The financial loss incurred from FMD alone which occurred on Nov. 2011 in Korea was estimated at 3 billion won, 23 % of annual livestock industry production. The livestock industry in Korea has greater risk of disease infection because of high density production, etc. Investigating the spread of livestock diseases should consider both direct and indirect contact as well as other various factors including airborne. Airborne infection of livestock disease was first hypothesised in the early 1900s, however, field experimental studies are still limited. Furthermore, no protocol is available in detecting airborne viruses in the field. In this study, effective virus samplers were investigated by comparative analysis of the type of samplers used detect to airborne virus. Laboratory experiments were conducted to compare virus samplers such as Bio-sampler, Dust-sampler, Compact-Cascade-Impactor (CCI) and Microflow in detecting PRRSV. Samples were analyzed by Reverse-Transcription PCR to assess the efficiency of the instrument in detecting the airborne virus. First, samples were classified into five levels according to light intensity of gel images and then the classified results were normalized. In every case, Bio-sampler and Dust-sampler were comparable with each other and have shown to be more effective than CCI and Microflow samplers.

추적가스 실험을 통한 축사 내 질병 확산 분석

송상현,이인복,권경석,하태환,홍세운,서일환,문운경,김연주,최은진,Song, Sang-Hyeon,Lee, In-Bok,Kwon, Kyeong-Seok,Ha, Tae-Hwan,Bitog, Jessie P.,Hong, Se-Woon,Seo, Il-Hwan,Moon, Oun-Kyeong,Kim, Yeon-Joo,Choi, Eun-Jin 한국농공학회 2012 한국농공학회논문집 Vol.54 No.3

Recently, the livestock industry in Korea was heavily affected by the outbreak of official livestock diseases such as foot and mouse disease, high pathogenic avian influenza, swine influenza, and so on. It has been established that these diseases are being spread through direct contact, droplet and airborne transmission. Among these transmissions, airborne transmission is very complex in conducting field investigation due to the invisibility of the pathogens and unstable weather conditions. In this study, the airborne transmission was thoroughly investigated inside a pig house by conducting tracer gas ($CO_2$) experiment because experiment with real pathogen is limited and dangerous. This is possible as it can be assumed that the flow is similar pattern very fine particles and gas. In the experiment, the ventilation structure as well as the location of gas emission were varied. The $CO_2$ detection sensors were installed at 0.5 and 1.3 m height from the floor surface. The tracer gas level was measured every second. Results revealed that the direction of spread can be determined by the response time. Response time refers to the time to reach 150 ppm from the gas emission source at each measuring points. The location of the main flow as well as the gas emission was also found to be very important factor causing the spread.

간척지 인근 농경지에서의 비산 및 부유먼지 확산 모니터링(II): 김제 모니터링

황현섭,이인복,신명호,홍세운,서일환,유재인,권경석,김용희,Hwang, Hyun-Seob,Lee, In-Bok,Shin, Myeong-Ho,Hong, Se-Woon,Seo, Il-Hwan,Yoo, Jae-In,Bitog, Jessie.P.,Kwon, Kyeong-Seok,Kim, Yong-Hee 한국농공학회 2009 한국농공학회논문집 Vol.51 No.2

A study on fugitive dusts was conducted at Saemangeum reclaimed land located in Gim-je area. The monitoring result on the fugitive and suspended dust was significantly affected by the farming activities (harvesting and land cultivation) and vehicles passing nearby the measuring points. The concentration of the fugitive dust generated from the reclaimed land was reduced remarkably by the effect of halophyte present on the ground and the tide embankment. Comparing the data collected in 2006 and 2007, the concentrations of TSP and PM10 decreased by 47.4% and 29.5%, respectively. After harvesting operations at paddy field, TSP increased by 22% while PM10 increased by 54%. The concentration of a Cl- which is a representative ion of sea-salt decreased to about 35% in 2007 compared with 2006. This represents that the inside area change and plant covering rate affected on the decrease of fugitive dust. The correlation analysis for the compounds of topsoil at each measuring point shows that near the coastline is more comparable. The canopy of halophyte in the source area also increased which reduced the fugitive dust remarkably. The dust distribution measured by dust spectrometer at the same point shows that most particles are $0.5{\mu}m$ to 2um size but not greater than $5{\mu}m$.

강제 환기식 육계사 다중 입기 슬롯에서의 입기류 도달거리 분석

권경석,하태환,이인복,홍세운,서일환,Kwon, Kyeong-Seok,Ha, Tae-Hwan,Lee, In-Bok,Hong, Se-Woon,Seo, Il-Hwan,Jessie, P. Bitog 한국농공학회 2012 한국농공학회논문집 Vol.54 No.2

In the winter season, when the ventilation system is operating, the fresh cold air from the slot-type openings of broiler house which directly reached the animal zone can cause various problems such as thermal stress, decreasing of feed and water consumption, occurrence of respiratory disease, and etc. Therefore it is very important to control the trajectory of aero-flow from the slot openings to induce an efficient thermal heat change. Jet-drop distance model was proposed to predict and control the jet-trajectory. However their study was restricted due to the small scaled model and difficulties of measuring the Jet-drop distance. In this study, CFD was applied to analyze qualitatively and quantitatively the jet-drop distance in a real broiler house. The various variables were considered such as installed slot-angle, designed ventilation rate, and the outdoor ambient temperature. From the present study, two linear-regression models using the Jet-drop factor and corrected Archimedes number, and their R-squared values 0.744 and 0.736, respectively, were used. From this study, the applicability of CFD on the analysis of Jet-drop distance model was confirmed.