원예용 상토와 제지 슬러지의 혼합비율에 따른 상추의 생육반응

최재혁(Jaehyuck Choi),박봉주(Bong-Ju Park) 한국펄프·종이공학회 2016 펄프.종이技術 Vol.48 No.4

This study was conducted to investigate the impact of paper mill sludges substrates on the growth responses of lettuce that are commonly chosen by people. Lettuces (Lactuca sativa ‘Seonmang jeokchukmyun’) were potted and grown for 6 weeks with four different mixing ratio of horticultural substrate and paper mill sludge (8:2, 6:4, 4:6 and 2:8) in a greenhouse. As results, 8:2 was the most effective mixing ratio for the growth of lettuce. This mixing ratio showed significant differences in all categories of plant height, leaf length, leaf width, leaf area and biomass. 6:4 mixing ratio had a growing problem at an early stage and recovered later. 4:6 and 2:8 mixing ratios did not affect its growth.

고흡수성 폴리머와 나노셀룰로오스 배합비에 따른 스파티필럼의 생육 반응

최재혁(Jaehyuck Choi),박봉주(Bong-Ju Park) 한국펄프·종이공학회 2020 펄프.종이기술 Vol.52 No.5

원예용 상토와 제지 슬러지 배합비별 들깨 생육반응

최재혁(Jaehyuck Choi),조혜빈(Hye-Bin Jo),박봉주(Bong-Ju Park) 한국펄프·종이공학회 2016 펄프.종이기술 Vol.48 No.6

This study was conducted to investigate the impact of paper mill sludge substrates on the growth responses of perilla that is commonly chosen by people. Perilla (Perilla frutescens var. japonica Hara ‘Jeok Ssam Ip’) were potted and grown for 8 weeks with five different mixing ratios of horticultural substrate and paper mill sludge (9:1, 7:3, 5:5, 3:7 and 1:9) in a greenhouse. As results, the 9:1 was the most effective mixing ratio for the growth of perilla. This mixing ratio showed significant differences in all categories of plant height, leaf length, leaf width, leaf area and biomass. The 7:3 and 5:5 mixing ratios had a growing problem at an early stage and recovered later. The 5:5, 3:7 and 1:9 mixing ratios did not effective on growth. In conclusion, paper mill sludge should be used 30% or less as substrate for the growth of perilla.

빅데이터를 활용한 휴양림 이용객현황과 인터넷 검색어의 상관관계분석

최재혁(Choi, Jaehyuck),신창섭(Shin, ChangSeob) 한국산림휴양복지학회 2015 한국산림휴양학회지 Vol.19 No.4

본 연구는 휴양림을 찾는 이용객들의 수요를 관련 트렌드데이터와 검색어를 이용하여 사전에(Proactive) 예측하고, 미리 대비할 수 있는 방안을 찾아보기 위해, 구글과 네이버에서 제공하는 트렌드 데이터를 이용하여, 상관관계를 분석하였다. 상관관계분석결과 , 캠핑인구가 꾸준히 증가하는 추세를 반영하듯 이용객 현황과 강한 상관관계를 가지는 검색어들로 구글트렌드 데이터를 이용했을 때는 ‘휴양림’과 ‘캠핑관련용어들’이 수요예측에 적합한 것으로 나타났으며, 데이터 이용 시 같은 달 데이터를 비교하는 것이 가장 정확한 예측치를 산출할 수 있을 것으로 예상되며, 네이버트렌드 모바일 데이터를 이용하였을 때는 같은 달 데이터 보다는 한·두 달 전 데이터와 강한 상관관계를 보인 ‘휴양림’과 다른 조합의‘캠핑관련용어들’을 이용하여 예측치를 추정하는 것이 가장 합리적인 방법으로 나타났다. Big data, Google Trends and Naver Trends Mobile data, was used to find out how to prepare and manage recreational forests. Volume of recreational forest visitors and residents are good indicators to decide long and/or short term policy. Therefore, Person correlation analysis was employed to test for the relationship between volume of recreational forest visitors and internet search words. In this study, meaningful results were found through the process. Results of correlation analysis between Google Trends data and Visitors pattern data showed that Recreational Forests’ and ‘Camping related search words’were strongly correlated with trend data of the same month or one month ago. Results of correlation analysis between Naver Trends Mobile data and visitors pattern data also showed that ‘Recreational Forests’ and different combination of‘Camping related search words’ were strongly correlated. In this case, one or two months delayed visitors pattern data were resulted in better and stronger correlation than data of the same month. These search words can be used as variables in the forecasting volume of recreational forest visitors and residents.

식물 내건성 평가를 통한 제지 슬러지의 옥상녹화 이용 가능성 연구

최재혁(Jaehyuck Choi),박봉주(Bong-Ju Park) 한국펄프·종이공학회 2016 펄프.종이기술 Vol.48 No.6

The purpose of this study was to find out the possibility of paper mill sludge application for green roof by assessing drought tolerance of Hosta longipes with five different mixing ratio of paper mill sludge and horticultural substrate (9:1, 7:3, 5:5, 3:7 and 1:9). From August 11th to September 29th, number of leaves, plant height, leaf size, chlorophyll content, volumetric water content, evapotranspiration, and relative water content (RWC) were measured. As results, 9:1 was reached 0% of volumetric water content earliest and withered earliest on 35th day of unirrigated experiment, and 7:3 was withered on 42th day. All other mixing ratios were withered on 43th day or later. As for chlorophyll content, all mixing ratios steadily decreased and showed similar patterns. Number of leaves and leaf size were very stable for 21 days and then rapidly decreased. Soil moisture reduction patterns were almost same and evapotranspiration reduction was directly proportional to ratio of horticultural substrate. In conclusion, 50% or less of paper mill sludge application does not significantly affect drought tolerance of H. longipes so that paper mill sludge can be used as substrate for green roof.

인공강우기를 이용한 바이오 숯의 그린루프 재료 적합성 연구

최재혁(Jaehyuck Choi),신수정(Soo-Jeong Shin),김병로(Byung-Ro Kim) 한국펄프·종이공학회 2016 펄프.종이技術 Vol.48 No.6

A rainfall simulator is developed to evaluate the adequacy of biochar (Korean traditional charcoals) as a content of green roof substrate. Three different sets of rainfall intensity and rainfall duration (10 minute test with 240 rainfall intensity, 1 hour test with 70 rainfall intensity, 1 day test with 29.8 rainfall intensity) are applied to collect data such as moisture content, amount of adsorbed water, and amount of evaporation. All charcoals quickly absorb rainwater and keep absorbing in a different way. Mechanical charcoal (MC) and traditional black charcoal (TBC) 3 have better absorbing abilities than other charcoals. All charcoals evaporate all the moisture within 3 to 7 days. MC adsorbs 146.3% of water in a one day test and evaporates for 7 days. MC is also the lightest. Even though results of test show various degrees, MC is the best charcoal as green roof content and other five charcoals also have valuable abilities as well.

나노셀룰로오스 혼합토에서의 쑥부쟁이 생육 반응

최재혁(Jaehyuck Choi),박봉주(Bong-Ju Park) 한국펄프·종이공학회 2021 펄프.종이기술 Vol.53 No.4

건조스트레스에 따른 옥상녹화 식물의 생리적 반응

박성식,최재혁,박봉주,Park, Seong-Sik,Choi, Jaehyuck,Park, Bong-Ju 한국조경학회 2017 韓國造景學會誌 Vol.45 No.2

본 연구는 저관리 경량형 옥상녹화를 위해 맥문동, 울릉국화, 비비추, 돌나물, 잔디의 내건성을 평가하였다. 옥상녹화 식물의 내건성 평가를 위해 용적수분함량, 엽과 토양의 수분포텐셜, 엽록소 a와 b함량, 엽록소형광, 광합성율, 기공전도도, 증산속도, 항산화물질을 측정하였다. 옥상녹화 식물의 내건성 측정결과, 무관수 일수가 경과하면서 용적수분함량 부족에 따라 식물은 점차 고사하는 경향을 보였다. 울릉국화가 가장 먼저 고사하였으며, 그 다음으로 잔디, 비비추, 맥문동 순이었으며, 돌나물은 고사하지 않았다. 비비추, 맥문동, 돌나물은 3주 이상 생존하여 내건성이 높은 식물로 판단되었다. 엽록소 a와 b는 두 가지 유형이 나타났는데, 초기부터 중기까지 일정한 함량을 유지 후, 급격히 감소하는 I유형에는 비비추, 잔디와 초기에는 낮은 함량을 보이다가 중기 때 급격히 증가 후, 감소하는 II유형에는 울릉국화, 맥문동, 돌나물로 구분되었다. 용적수분함량과 증발산량은 모든 식물 종에서 지속적으로 감소하였으며, 엽록소형광 측정결과, 내건성이 상대적으로 높은 돌나물이 가장 늦게 감소하였고, 잔디와 돌나물은 급격한 감소가 나타난 후 고사하였다. 광합성, 기공전도도, 증산속도는 초기에 높은 활성도가 나타났으나, 용적수분함량의 감소로 인하여 식물체가 기공을 닫아 낮아지는 경향을 보였다. 항산화물질 측정결과, 건조스트레스가 증가하면 항산화물질의 양 또한 증가하나, 높은 스트레스가 유지되면 이러한 화합물이 지속적으로 소비되므로, 항산화물질의 증감은 내건성 평가 지표로 사용할 수 있을 것으로 판단된다. This study evaluated the drought tolerance of Liriope platyphylla F.T.Wang & T.Tang, Dendranthema zawadskii var. lucidum (Nakai) J.H.Park, Hosta longipes (Franch. & Sav.) Matsum., Sedum sarmentosum Bunge and Zoysia japonica Steud. for an extensive green roof. In order to assess drought tolerance of green roof plants, several criteria were measured such as volumetric water content, leaf and soil moisture potential, chlorophyll a and b, chlorophyll fluorescence, photosynthesis, stomatal conductance, transpiration rate and antioxidants. The results of the drought tolerance measurement of green roof plants focused on the gradually withering of plants from lack of volumetric water content. D. zawadskii was the first to show an initial wilting point, followed by Z. japonica, H. longipes and L. platyphylla in order while S. sarmentosum showed no withering. It was concluded that H. longipes, L. platyphylla and S. sarmentosum were highly drought tolerant plants able to survive over three weeks. Furthermore, chlorophyll a and b were divided into two types: Type I, which kept regular content from the beginning to the middle of the period and suddenly declined, like H. longipes and Z. japonica; and Type II, which showed low content at the beginning, sharply increased at the middle stage and decreased, like D. zawadskii, L. platyphylla and S. sarmentosum. Volumetric water content and the amount of evapotranspiration consistently declined in all plant species. The analysis of chlorophyll fluorescence results that S. sarmentosum, which had relatively high drought tolerance, was the last to decline, while Z. japonica and S. sarmentosum withered after rapid reduction. At first, photosynthesis, stomatal conductance and transpiration rate showed high activity, but they lowered as the plant body closed stomata owing to the decrease in volumetric water content. Measuring antioxidants showed that when drought stress increased, the amount of antioxidants grew as well. However, when high moisture stress was maintained, this compound was continuously consumed. Therefore, the variation of antioxidants was considered possible for use as one of the indicators of drought tolerance evaluation.

천연가황고무의 열경화에 따른 경도 및 물성치, 피로수명 변화

강희진(Heejin Kang),최재혁(Jaehyuck Choi),강한보(Hanbo Kang),정현용(Hyunyong Jeong),이태수(Taesoo Lee) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_3

Naturnl vulcanized rubber is one of the mostly used materials in industry because of its hyper-elasticity and large deformability. However, the material properties of rubber slowly change and rubber become brittle as time goes on. So, it is imponant to predict the mechanical behavior and futigue life of aged rubber material. Thus, in this paper rubber specimens were heat-aged to accelerate the aging process, and hardness of rubber (IRHD) was proposed to use to indicate the amount of the aging process. In addition, the mechanical properties and futigue life of heat-aged specimens were obtained. Then, the material properties and futigue life of heat aged vulcanized rubber specimens were obtained and represented as a function of IRHD.

유동공진을 위한 가진기 설계 및 평가

남윤수(Yoonsu Nam),최재혁(Jaehyuck Choi) Korean Society for Precision Engineering 2001 한국정밀공학회지 Vol.18 No.6