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사과의 산지도매가격과 소매가격 간 동태적 인과성 및 비대칭적 가격 조정 연구
김기환 ( Gihwan Kim ),서병선 ( Byeongseon Seo ) 한국농업경제학회 2017 農業經濟硏究 Vol.58 No.1
The purpose of this study is to explore the dynamic properties of causality and asymmetric price transmission in the distributional channel of the apple market in Korea. Using the wholesale and retail price series of the apple market, we obtain the following results. First, the price transmission mechanism reveals the causal relationship channeling from the wholesale price to the retail price. Second, we find an asymmetric price transmission from the analysis using the threshold partial adjustment model. The retail price responds strongly when the wholesale price increases. On the other hand, the retail price shows sluggish adjustment when the wholesale price decreases. This study has shown a significant improvement of forecasting accuracy as the threshold partial adjustment model allows for asymmetric price transmission.
Lactobiocin의 피부 염증 및 여드름 저해효과에 관한 연구
김광수 ( Kwangsoo Kim ),오세종 ( Sejong Oh ),김기환 ( Gihwan Kim ),홍진천 ( Jinchon Hong ),이승화 ( Seunghwa Lee ) 대한화장품학회 2002 대한화장품학회지 Vol.28 No.1
The purpose of this study was to evaluate bacteriocin activity against human flora. Lactobiocin, a bacteriocin produced by Lactococcus sp. HY 449, inhibited the growth of Starphylococcus epidermidis, Starphylococcus aureus, Streptoccoccus pyogenes and Propionibacterium acnes. When crude bacteriocin was added to indicator cells during logarithmic growth, the optical density(O.D 650nm) of cells without bacteriocin increase after 5h of incubation. Whereas in the presence of bacteriocin, the O.D of cell suspensions decreased. The similar patterns were observed for absorbance readings at 280 nm and 260 nm. The release of cellular components when cell were treated with Lactobiocin suggests some degree of membrane damage or cell lysis. Scanning electron microscopy of cells following treatments with Lactobiocin in PBS buffer revealed disruptures of cell morphology. These results indicate that bacteriocin appears to cause cell lysis of tested strains. In cytotoxicity on human fibroblast, LD50/ of Lactobiocin was ca. 50 mg/ml and no change was observed cell proliferation at the same concentration. Any irritation and allergic reaction did not observed when evaluated by human patch test for Lactobiocin.
코로나 19 상황에서 안전한 실내체육시설 출입을 위한 카카오톡채널기반 입출입 관리 시스템 개발
김기현(KIHYUN, KIM),김기환(GIHWAN, KIM) 한국HCI학회 2023 한국HCI학회 학술대회 Vol.2023 No.2
우리사회는 코로나 19 팬더믹 이후로 비대면 사회로의 전환이 이루어지고 있다. 이 과정에서 실내체육시설은 방역조치차원에서 임시폐쇄 되었으며 생활체육인의 감소의 원인이 되었다. 이를 해결하고자 안전한 실내체육활동을 위해 VR 시스템 활용, QR 코드를 이용한 출입 관리 등 다양한 연구가 진행되고 있다. 본 연구에서는 본 연구에서는 안전한 실내 체육시설 출입을 위하여 사전 스크리닝 실시, QR 코드 입출입관리, 사전 방문 예약 기능을 통해 코로나 19 와 같은 팬더믹 상황에서 보다 안전하게 출입을 할 수 있도록 카카오톡 채널을 기반으로 한 입출입 관리 시스템을 개발하고자 한다.
RLD 기반 타이어 연계 쿼터 서스펜션 모듈 특성에 관한 연구
김현일(Hyunil Kim),유덕현(Duckhyun Yu),진병옥(Byungok Jin),김기환(Gihwan Kim),이태희(Taehee Lee) 한국자동차공학회 2018 한국자동차공학회 부문종합 학술대회 Vol.2018 No.6
The development process of a modern car suspension system consider the target value of the suspension parts characteristics according to purpose of vehicle development. It apply to the design by referring to the benchmark data of the competition vehicle segment and the existing development DB(database). However, it is difficult to predict the actual characteristics of the suspension, so it is necessary to tuning the characteristics of the suspension parts and the specifications of the tires through vehicle tests. A variety of test methods are used for quantitative evaluation, because suspension test is almost subjective test. In this Study, we produce a road test condition by reproducing displacement and load based on RLD measured by vehicle test, and propose a characteristic test method of Tire Coupled Quarter Suspension Module.
F1 서킷 실차시험 데이터 기반 가진 재현 시험을 통한 감쇠력 특성 분석
김현일(Hyunil Kim),진병옥(Byungok Jin),김기환(Gihwan Kim),나재원(Jaewon Nah),이혜민(Hyemin Lee),이태희(Taehee Lee) 한국자동차공학회 2017 한국자동차공학회 부문종합 학술대회 Vol.2017 No.5
In this study, we developed a damper test method of damper test rig which can reproduce actual vehicle driving test based on vehicle driving data in Korea International Circuit(KIC). Damper displacement data of the test vehicle were measured by potentiometer. The damper test method was developed by adjusting the gain value of the damper test rig to coincide the actual measured damper displacement data of the vehicle with the damper displacement data in the damper test rig. Finally, we analyzed the results before and after the damper test developed in this study to compare damping characteristics.