젖소 사육에서 탄소 순환 체계에 관한 고찰 연구

김기연,고한종,김치호,최은규,김종구,유영선,김현태,Kim, Ki-Youn,Ko, Han-Jong,Kim, Chi-Ho,Choi, Eun-Gyu,Kim, Joung-Ku,Ryou, Young-Sun,Kim, Hyeon-Tae 한국축산환경학회 2012 축산시설환경학회지 Vol.18 No.1

젖소를 사육하는 유우농가 마을을 대상으로 선행 국내/외 문헌자료들에 대한 고찰을 통해 탄소 유입과 배출에 따른 각 부문별 발생량 원단위에 대한 다음과 같은 결론을 도출하였다. 1. 젖소 사육과정에서 탄소 유입에 대한 발생량 원단위는 젖소의 사료 섭취에 의한 탄소 유입(${\fallingdotseq}$ 5.9 ton C/head/year), 젖소 분뇨 퇴비를 초지로 환원시 탄소 유입(${\fallingdotseq}$ 2.3 ton C/head/year), 초지가 함유하고 있는 유기탄소(${\fallingdotseq}$ 318g C/$m^2$/year), 사료작물이 함유하고 있는 유기탄소(${\fallingdotseq}$ 145 g C/$m^2$/year) 및 광합성에의한 대기 중 $CO_2$의 초지 사료작물 흡수(${\fallingdotseq}$ 17 g C/$m^2$/year)로 정리할 수 있다. 2. 젖소 사육과정에서 탄소 배출에 대한 발생량 원단위는 젖소 호흡 및 트림에 의한 대기 중으로 $CO_2$와 $CH_4$ 배출(${\fallingdotseq}$ 2,9 ton C/head/year), 젖소 분뇨내 유기탄소 분해에 의한 대기 중으로 $CO_2$와 $CH_4$ 배출(${\fallingdotseq}$ 0.4 ton C/head/year), 초지에서 대기 중으로의 $CO_2$ 배출(${\fallingdotseq}$ 440 g C/$m^2$/year), 및 초지 내 유기탄소의 지하수 용출(${\fallingdotseq}$ 0)로 정리 할 수 있다. The first objective of this study is to estimate emission coefficient of organic carbon regarding its inflow and discharge for dairy farm through reviewing domestic and foreign literature published or reported previously. Its second objective is to provide fundamental data to establish carbon cycle system related to livestock production. Based on literature review, emission coefficients by inflow of organic carbon into dairy farm were 5.9 ton C/head/year for feedstuff ingestion by milk cow, 2.3 ton C/head/year for recycling manure compost of milk cow to grassland, 318 g C/$m^2$/year for contents in grassland, 145 g C/$m^2$/year for contents in fodder crop, and 17 g C/$m^2$/year for $CO_2$ uptake by fodder crop, respectively. on the other hand, emission coefficients by discharge of organic carbon from dairy farm were 2,9 ton C/head/year for emission of $CO_2$ and $CH_4$ by respiration and burp of milk cow, 0.4 ton C/head/year for emission of $CO_2$ and $CH_4$ by decomposition of organic carbon in manure of milk cow, 440 g C/$m^2$/year for emission of $CO_2$ from grassland, and 0 for elution of organic carbon in grassland into underground water, respectively.

복합식 공기청정기의 물리적 및 생물학적 입자상 물질의 제거 효과

김기연,김치년,김윤신,노영만,이철민,Kim, Ki-Youn,Kim, Chi-Nyon,Kim, Yoon-Shin,Roh, Young-Man,Lee, Cheol-Min 한국환경보건학회 2006 한국환경보건학회지 Vol.32 No.5

There was no significant difference in the CADR (Clean Air Delivery Rate) between physical aerosols, NaCl and smoke, and biological aerosols, airborne MS2 virus and P. fluorescens, which implicate that the hybrid-type of air purifier, applying the unipolar ion emission and the radiant catalytic ionization, imposed identical reduction effect on both physical aerosol and bioaerosol. Ventilation decreases the efficiency of air cleaning by unipolar ionization because high ventilation diminishes the particle concentration reduction effect. The particle removal efficiency decreases with increase in the chamber volume because of the augmented ion diffusion and higher ion wall loss rate. Particle size affects the efficiency of air ionization. The efficiency is high for particles with very small diameter because reduction of charge increases with particle size. If there is no increasing supply of ions, the efficiency of air cleaning by unipolar ionization increases with respect to initial concentration of particles because of the large space charge effect at high particle concentration and amplified electric field.

서울시 일부 지역의 대기 중 부유 진균의 분포 특성

김기연,김대근,Kim, Ki-Youn,Kim, Dae-Keun 한국환경보건학회 2012 한국환경보건학회지 Vol.38 No.5

Objectives: This study was performed to assess based on field investigation the distribution characteristics of airborne fungi in an area of Seongdong-gu, Seoul. Methods: Three sites, a living area, forest and traffic site, were selected for evaluation of monthly level of outdoor airborne fungi. An on-site survey was executed between January 2009 and December 2009. During the experimental period, air sampling was performed every month in the afternoon (2:00 pm-5:00 pm) using a cascade impactor. Results: Outdoor airborne fungi measured in Seoul, Korea over one year showed a concentration range from 850CFU $m^{-3}$ to 15,200CFU $m^{-3}$. The mean respirable fraction of outdoor airborne fungi was 67% compared to total concentration. Regardless of measurement site, there was no significant concentration difference in outdoor airborne fungi between periods of yellow dust and non-yellow dust (p>0.05). There was no significant correlation relationship between outdoor airborne fungi and atmospheric factors such as temperature and relative humidity. The predominant genera of airborne fungi identified were Aspergillus, Cladosporium, Paecilomyces and Penicillium. Conclusion: Monthly levels of outdoor airborne fungi were highest in April and November and lowest in August. In seasonal concentration distribution, the autumn showed the highest level of outdoor airborne fungi, followed by spring, summer and winter. In regional concentration distribution, the highest level of outdoor airborne fungi was generally found in the forest, followed by the living area and traffic site.

공기정화기 가동에 따른 사무실 재실자들의 행동성과 입자상 오염물질의 농도 분포 관계에 관한 연구

김기연,박재범,김치년,이경종,Kim, Ki-Youn,Park, Jae-Beom,Kim, Chi-Nyon,Lee, Kyung-Jong 한국환경보건학회 2007 한국환경보건학회지 Vol.33 No.4

The reduction efficiency of air cleaner on particulate contaminants such as dust, airborne bacteria and fungi distributed in the office was relatively higher in case of office with workers than office without workers. This result would be attributed to workers' activities and physical characteristics of particulate contaminants. The air cleaner decreased a concentration of airborne bacteria more than airborne fungi, which implicates that difference of dust adsorption between airborne bacteria and fungi would affect an operation efficiency of air cleaner.

서울시 일부 지하철역 내 분포하는 부유 세균 및 입자상 오염물질 평가

김기연,박재범,김치년,이경종,Kim, Ki-Youn,Park, Jae-Beom,Kim, Chi-Nyon,Lee, Kyung-Jong 한국환경보건학회 2006 한국환경보건학회지 Vol.32 No.4

In activity areas of subway workers and passengers in Seoul metropolitan subway lines 1-4, mein concentrations of airborne bacteria were relatively higher in workers' bedroom and station precinct whereas concentrations of particulate matters, $PM_{10}$ and $PM_{2.5}$, were relatively higher in platform, inside train and driver's seat as compared with other activity areas. This result indicates that little correlation between airborne bacteria and particulate matters was found, which assumed that most airborne particulate matters distributed in subway consisted of mainly inorganic dust like a metal particles. Mean concentrations of $PM_{10}$ and $PM_{2.5}$ in station precinct and platform exceeded the threshold limit value ($PM_{10}:150{\mu}g/m^3,\;PM_{2.5}:65{\mu}g/m^3$) but those in station office and ticket office were below it. The genera identified in all the activity areas of subway over 5% detection rate were Staphylococcus, Micrococcus, Bacillus and Corynebacterium, of which Staphylococcus and Micrococcus covered over 50% of total airborne bacteria and were considered as predominant genera distributed in subway.

인터넷전화 수용 결정요인과 사용자 연령 및 경험 변수의 조절효과 분석

김기연,이덕선,설정선,이봉규,Kim, Ki-Youn,Lee, Duk-Sun,Seol, Jeong-Seon,Lee, Bong-Gyou 한국정보처리학회 2009 정보처리학회논문지D Vol.16 No.6

본 연구의 목적은 첫째, 인터넷전화(Voice over Internet Protocol)의 사용자 수용에 미치는 결정요인을 정의하고, 둘째, 수용 이론들의 통합모형인 UTAUT를 기저모형으로 하여, 성과기대감, 사회적 영향, 노력기대감, 사용촉진조건, 행위의도와 사용행위 등의 잠재변수 간의 복합적인 인과관계를 검증하는 것이다. 셋째, 비용기대감 변수를 새롭게 정의하여 연구가설에 포함하였고, 각 변수들 간의 경로에 영향을 주는 조절변수로서 사용자 연령, 성별, 경험기간의 조절효과를 분석하였다. 또한, VoIP의 실제 사용자 641명을 표본 조사함으로써, 행위의도와 사용행위 변수 간의 개념적 차이를 명확히 구분하여 보다 정확한 분석 결과의 향상을 도모하였다. 사용자 수용에 대한 기존 연구들은 사용행위 변수를 검증할 때, 실제 사용자뿐만 아니라 긍정적인 행위의도를 가진 미래의 잠재적 사용자를 포함시키는 사례가 많았다. 분석 결과, 제시한 모든 연구가설이 채택되었으며, 조절효과에서 연령이 성과기대감, 사회적 영향과 행동의도 간에, 경험기간은 사용촉진조건, 행위의도와 사용행위 간에 정의 관계가 성립하였다. The purpose of this study is to define determinants of VoIP user acceptance and to verify significant causality among latent variables - performance expectancy, effort expectancy, cost expectancy, social influence, facilitating conditions, behavioral intend, use behavior - based on UTAUT model. We presented the expanded hypotheses including the new factor, cost expectancy and analyzed the moderating effect of user age, gender and usage experience variables. For a accuracy of predicted results, we focused on survey analysis with 641 real user samples. Compared to previous studies, it is meaningful that this research verified the conceptual difference between behavioral intention and usage behavior. As a result, all proposed hypotheses accepted and moderating effects are supported significantly in age and use experience moderating variables.

서울시 일부 지하철역 내 부유 진균, 입자상 물질, 이산화탄소의 분포 양상

김기연,박재범,김치년,이경종,Kim, Ki-Youn,Park, Jae-Beom,Kim, Chi-Nyon,Lee, Kyung-Jong 대한예방의학회 2006 예방의학회지 Vol.39 No.4

Objectives: The aims of this study were to examine the level of airborne fungi and environmental factors in Seoul metropolitan subway stations and to provide fundamental data to protect the health of subway workers and passengers. Methods: The field survey was performed from November in 2004 to February in 2005. A total 22 subway stations located at Seoul subway lines 1-4 were randomly selected. The measurement points were subway workers' activity areas (station office, bedroom, ticket office and driver's seat) and the passengers' activity areas (station precincts, inside train and platform). Air sampling for collecting airborne fungi was carried out using a one-stage cascade impactor. The PM and CO2 were measured using an electronic direct recorder and detecting tube, respectively. Results: In the activity areas of the subway workers and passengers, the mean concentrations of airborne fungi were relatively higher in the workers' bedroom and station precinct whereas the concentration of particulate matter, $PM_{10}\;and\;PM_{2.5}$, were relatively higher in the platform, inside the train and driver's seat than in the other activity areas. There was no significant difference in the concentration of airborne fungi between the underground and ground activity areas of the subway. The mean $PM_{10}\;and\;PM_{2.5}$ concentration in the platform located at underground was significantly higher than that of the ground (p<0.05). Conclusions: The levels of airborne fungi in the Seoul subway line 1-4 were not serious enough to cause respiratory disease in subway workers and passengers. This indicates that there is little correlation between airborne fungi and particulate matter.

반복 하중이 Full veneer crown의 유지력에 미치는 영향에 관한 연구

김기연,이선형,정헌영,양재호,허성주,Kim, Ki-Youn,Lee, Sun-Hyung,Chung, Hun-Young,Yang, Jae-Ho,Heo, Seong-Joo 대한치과보철학회 2000 대한치과보철학회지 Vol.38 No.5

Dislodgement of a crown or extension bridge and the loosening of a retainer of a bridge is a serious clinical problem in fixed restoration. Generally these problems are considered to be associated with deformation of the restoration. During biting, the restoration is subjected to complex forces and deforms considerably within the limit of its elasticity. Deformation of the restoration under the occlusal force induces excessive stress in the cement film, which then leads to the cement fracture. Such a fracture may eventually cause loss of the restoration. Because most of the past retention tests for full veneer crown were done without fatigue loading, they were not exactly simulating intraoral environment. And the purpose of this study was to evaluate the effect of cyclic cantilever loading on the retentive strength of full veneer crowns depending on different type of cements and taper of prepared abutment. Steel dies with $8^{\circ}\;or\;16^{\circ}$ convergence angle were fabricated through milling and crowns with the same method. These dies and crowns were divided into 8 groups. Group 1 : $16^{\circ}$ taper die, cementation with zinc phosphate cement, without loading Group 2 : $16^{\circ}$ taper die, cementation with zinc phosphate cement, with loading Group 3 : $8^{\circ}$ taper die, cementation with zinc phosphate cement, without loading Group 4 : $8^{\circ}$ taper die, cementation with zinc phosphate cement, with loading Group 5 : $16^{\circ}$ taper die, cementation with Panavia 21, without loading Group 6 : $16^{\circ}$ taper die, cementation with Panavia 21, with loading Group 7 : $8^{\circ}$ taper die, cementation with Panavia 21 without loading Group 8 : $8^{\circ}$ taper die, cementation with Panavia 21, with loading After checking the fit of die and crown, the luting surface of dies and inner surface of crowns were air-abraded for 10 seconds. The crowns were cemented to the dies, with cements mixed according to the manufacturer's recommendations. A static load of 5kg was then applied for 10 minutes with static loading device. Twenty-four hours later, group 1, 3, 5, 7 were only thermocycled, group 2, 4, 6, 8 were subjected to cyclic loading after thermocycling. Retentive tests were performed on the Instron machine. From the finding of this study, the following conclusions were obtained 1. Panavia 21 showed significantly higher retentive strength than zinc phosphate cement for all groups (p<0.05). 2. There was a significant difference in the retentive strength between $8^{\circ}\;and\;16^{\circ}$ taper for zinc phosphate cement(p<0.05), but no significant difference for Panavia 21 (p>0.05). 3. Cyclic loading significantly decreased the retentive strength for all groups(p<0.05). 4. For zinc phosphate cement, there was 35% reduction of the retentive strength after loading in the $16^{\circ}$ taper die, 25% in the $8^{\circ}$ taper die, and for Panavia 21, 21% in the $16^{\circ}$ taper die, 18% in the $8^{\circ}$ taper die.

가축분뇨 자원화시설에서 발생되는 암모니아와 황화수소의 계절별 현장 평가

김기연,Kim, Ki Youn 한국축산환경학회 2015 한국축산시설환경학회지 Vol.21 No.2

The objective of this study is to measure the levels of ammonia and hydrogen sulfide in livestock manure composting facility according to seasonal condition. Mean concentrations of ammonia in livestock manure composting facility were 84.3 (${\pm}15.2$) ppm for spring, 115.2 (${\pm}34.7$) ppm for summer, 76.2 (${\pm}18.9$) ppm for autumn, and 38.1 (${\pm}10.4$) ppm for winter, respectively. Based on the results obtained from this study, the seasonal levels of ammonia in livestock manure composting facility were highest in summer followed by autumn, spring and winterroom (p<0.05). Mean concentrations of hydrogen sulfide in livestock manure composting facility were 7.46 (${\pm}2.24$) ppm for spring, 9.42 (${\pm}2.82$) ppm for summer, 8.15 (${\pm}3.06$) ppm for autumn, and 10.18 (${\pm}4.11$) ppm for winter, respectively. The livestock manure composting facility showed the highest levels of hydrogen sulfide in winter followed by summer, autumn and spring. However, there was no significant difference of hydrogen sulfide concentration among seasons (p>0.05). 본 연구의 목적은 가축분뇨 자원화시설에서 배출되는 주요 악취물질을 대상으로 계절별 현장 방문 조사를 통해 전반적인 악취발생 현황을 파악하고 가축분뇨 자원화시설 운용시 효율적으로 적용될 수 있는 악취 저감대책을 설정하기 위한 기초 데이터 구축이다. 횡형 로터리 (Rotary) 교반방식의 퇴비화시설 내부의 암모니아 발생 농도는 봄철은 84.3 (${\pm}15.2$) ppm, 여름철은 115.2 (${\pm}34.7$) ppm, 가을철은 76.2(${\pm}18.9$) ppm, 겨울철은 38.1 (${\pm}10.4$) ppm으로 측정되었다. 분석 결과 여름철이 가장 높은 것으로 나타났고, 다음으로 가을철 > 봄철 > 겨울철인 것으로 조사되었다 (p<0.05). 반면 황화수소 발생 농도는 봄철은 7.46(${\pm}2.24$) ppm, 여름철은 9.42 (${\pm}2.82$) ppm, 가을철은 8.15 (${\pm}3.06$) ppm, 겨울철은 10.18 (${\pm}4.11$) ppm으로 측정되었다. 분석 결과 겨울철이 가장 높은 것으로 나타났고, 다음으로 여름철 > 가을철 > 봄철인 것으로 조사되었으나, 계절별 통계적 차이는 유의하지 않은 것으로 조사되었다 (p>0.05).

유기성 폐기물 자원화 시설에서 발생되는 부유 세균의 분포 특성

김기연,고한종,김대근,Kim, Ki-Youn,Ko, Han-Jong,Kim, Dae-Keun 한국환경보건학회 2012 한국환경보건학회지 Vol.38 No.2

Objectives: Bioaerosols released by treating organic-waste resources cause a variety of environmental and hygiene problems. The objective of this study was to investigate the distribution characteristics of the airborne bacteria emitted from a pig manure composting plant, a principal site for organic-waste resource facilities. Methods: Three types of pig manure composting plant were selected based on fermentation mode: screw type, rotary type and natural-dry type. Each site was visited and investigated on a monthly basis between September 2009 and August 2010. A total of 36 air samplings were obtained from the pig manure composting plants. The air sampling equipment was a six-stage cascade impactor. Quantification and qualification of airborne bacteria in the air samples was performed by agar culture method and identification technique, respectively. Results: The mean concentrations of airborne bacteria in pig manure composting plant were 7,032 (${\pm}1,496$) CFU $m^{-3}$ for screw type, 3,309 (${\pm}1,320$) CFU $m^{-3}$ for rotary type, and 5,580 (${\pm}1,106$) CFU $m^{-3}$ for natural dry type. The screw type pig manure composting plant showed the highest concentration of airborne bacteria, followed by the natural dry type and the rotary type. The ratio of respirable to total airborne bacteria was approximately 40-60%. The predominant genera of airborne bacteria identified were Micrococcus spp., Staphylococcus spp. and Escherichia spp. Conclusion: Monthly levels of airborne bacteria were highest in August and lowest in November regardless of fermentation mode. There was no significant correlation relationship between airborne bacteria and environmental factors such as temperature, relative humidity and particulate matters in pig manure composting plants.