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강제환기식 돈사의 환기 효율성 분석을 위한 CFD 모델 개발
서일환,이인복,홍세운,황현섭,유재인,권경석,하태환,김현태,Seo, Il-Hwan,Lee, In-Bok,Hong, Se-Woon,Hwang, Hyun-Seob,Bitog, Jessie Pascul,Yoo, Jae-In,Kwon, Kyung-Suk,Ha, Tae-Hwan,Kim, Hyeon-Tae 한국농공학회 2008 한국농공학회논문집 Vol.50 No.1
When livestock facilities in Korea have been changed larger and denser, rearing conditions have been getting worse and the productivity of animal production have been decreased. Especially in the cold season, the minimized ventilation has generally been operated to save energy cost in Korea resulting in very poor environmental condition and high mortality. While the stability, suitability, and uniformity of the rearing condition are the most important for high productivity, the ventilation configuration is the most important to improve the rearing condition seasonally. But, it is so difficult to analyze the internal air flow and the environmental factors by conducting only field experiment because the weather condition is very unpredictable and unstable as well as the structural specification can not be easily changed by the researchers considering cost and labor. Accordingly, an aerodynamic computer simulation was adopted to this study to overcome the weakness of conducting field experiment and study the aerodynamic itself. It has been supposed that the airflow is the main mechanism of heat, mass, and momentum transfers. To make the simulation model accurately and actually, simplified pig models were also developed. The accuracy of the CFD simulation model was enhanced by 4.4 % of errors compared with the data collected from field experiments. In this paper, using the verified CFD model, the CFD computed internal rearing condition of the mechanically ventilated pig house were analyzed quantitatively as well as qualitatively. Later, this developed model will be computed time-dependently to effectively analyze the seasonal ventilation efficiency more practically and extensively with tracer gas decay theory.
발열 또는 호흡기 증상 유무에 따른 119구급대 활동 시간 변화: 코로나 19 유행 전후 비교
서일환,김병권 대한응급의학회 2022 대한응급의학회지 Vol.33 No.3
Objective: We sought to compare the activity times of the 119 service ambulance units before and after the coronavirus disease 2019 (COVID-19) pandemic based on emergency medical service reports. Methods: This study analyzed the emergency medical service reports (1.26-10.31) of 69 ambulance units belonging to the Busan Fire Department in 2019 (before) and 2020 (after) the onset of the COVID-19 pandemic. This was a retrospective cross-sectional study to understand the changes in the activity times (response time, scene time interval, transport time interval, total prehospital time, turnaround time interval, and total activity time) according to the presence of fever or respiratory symptoms (symptom group). The data used for analysis included 150,771 cases, of which 79,121 were in 2019 and 71,650 in 2020, excluding incomplete transfer reports (128,082). Results: There was a total decrease of 7,471 cases in 2020. Compared to 2019, the dispatch and transport distance, outer dispatch jurisdiction, and transport to university hospitals increased. That was found to be greater in the symptom group than in the no symptom group. In the yearly comparison of activity times, there were significant differences in all the activity times and an overall increase in 2020. The increase in the active times was greater in the symptom group than in the no symptom group. Conclusion: In this study, the activity times of the 119 service ambulance units after the COVID-19 showed an increase compared to the pre-COVID period. Therefore, the concerned people must identify the factors which lead to delays and prepare a plan to shorten the activity times, thereby reducing the fatigue of paramedics and providing the means to enhance assistance for the well-being of patients.
Out of Sequence Measurement 환경에서의 MPDA 성능 분석
서일환,임영택,송택렬 대한전기학회 2006 전기학회논문지 D Vol.55 No.9(D)
- In a multi-sensor multi-target tracking systems, the local sensors have the role of tracking the target and transferring the measurements to the fusion center. The measurements from the same target can arrive out of sequence called the out-of-sequence measurements(OOSMs). Out-of-sequence measurements can arise at the fusion center due to communication delay and varying preprocessing time for different sensor platforms. In general, the track fusion occurs to enhance the tracking performance of the sensors using the measurements from the sensors at the fusion center. The target informations can arrive at the fusion center with the clutter informations in cluttered environment. In this paper, the OOSM update step with MPDA(Most Probable Data Association) is introduced and tested in several cases with the various clutter density through the Monte Carlo simulation. The performance of the MPDA with OOSM update step is compared with the existing NN, PDA, and PDA-AI for the air target tracking in cluttered and out-of-sequence measurement environment. Simulation results show that MPDA with the OOSM has compatible root mean square errors with out-of-sequence PDA-AI filter and the MPDA is sufficient to be used in out-of-sequence environment.
서일환,김광주 한국결정학회 1990 韓國結晶學會誌 Vol.1 No.1
International Tables of X-Ray Crystallography Vol.IV(1974) Table 2.3.2에 오자가 있다. 점군 422의 등가반사면들은 hkl=hkl=hkl=hkl=hkl=khl=khl=khl이다. We point out an error in the Table 2.3.2 of International Tables of X-Ray Crystallograhy Vol. IV(1974). The equivalent reflections of the point group 422 should be hkl=hkl=hkl=hkl=hkl=khl=khl=khl.
X-선 분말회절에 의한 결정구조 해석을 위한 결정면의 다중도 인자
서일환,추금홍 한국결정학회 1992 韓國結晶學會誌 Vol.3 No.2
동일한 면간거리와 동일한 강도를 갖는 면들의 수로써 정의되는 한 면형(form)의 다중도 인자를 11개의 Laue군의 대칭성에 기초하여 국표화하였다. The multiplicity factor, which is defined as the number of different planes in a form having identical interplanar spacing and identical intensity, is tabulated here for the eleven Laue groups on the basis of their symmetries.
서일환,이진현 한국결정학회 1993 韓國結晶學會誌 Vol.4 No.1
The knowledge on the number of necessary and collectable reflections for the crystal structure analysis is greatly helpful in choosing the conditions for X-ray intensity data collection using automatic four circle diffractometer. In this paper, we represent a method to calculate the total unmber of collectable intensity date in an asymmetric unit.
양돈장의 소모성질병 확산 분석을 위한 현장 모니터링 및 공기유동학적 분석
서일환,이인복,문운경,권경석,Seo, Il-Hwan,Lee, In-Bok,Moon, Oun-Kyung,Kwon, Kyeong-Seok 한국농공학회 2014 한국농공학회논문집 Vol.56 No.1
Pig chronic wasting disease, including porcine reproductive and respiratory syndrome (PRRS) and postweaning multisystemic wasting syndrome (PMWS), have made a continuous economic damage in pig farms. Airborne spread of livestock viruses are an important spread factor which is difficult to analyze due to invisible airflow and limitation of measurement. The objective of this study is to analyze airborne disease spread between buildings in the experimental pig farm by means of field experiment and computational fluid dynamics (CFD). The field experiments were conducted to capture airborne virus using air sampler and teflon filter along multi points in the experimental pig farm. The samples were tested in terms of virus detection resulting in positive reaction for PRRS and PCV-2 viruses, which can be a firm evidence of airborne virus spread. The CFD simulation model was developed by considering complex topography, wind conditions, building arrangement, and ventilation systems and was used to analyze airborne virus spread according to different wind conditions. The CFD computed result showed a possibility of airborne virus spread via livestock aerosol from infected pig house to neighboring pig houses according to wind directions. The CFD simulation technique is expected to provide significant data for estimating and making a counterplan against airborne disease spread.