Fe-3.0Ni-0.7Cr-1.4Mn-X강의 고주기피로특성에 미치는 질화/DLC코팅의 영향

장재철(Jae Cheol Jang),김송희(Song-Hee Kim) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.6

Various surface treatments and thin film coating processes on the surface of injection die steel have been developed to extend the life. Most of previous studies were mainly focused on investigating the wear and static bonding behavior of thin films. In this study complex surface treatments of DLC coating combined with ion nitriding were applied to increase fatigue life and wear resistance. Ion nitriding, DLC coating, and DLC coating following nitriding on the surface of Fe-3.0Ni-0.7Cr-1.4Mn-X steel were investigated to uncover the beneficial effect which is applicable to injection die. The effect of various surface treatments and coating conditions on high cycle fatigue resistance was studied. Surface morphology change during fatigue tests were observed with AFM. Fatigue life of the die steel increased by 10 to 1,000 times at the various level of stress amplitudes in the condition of DLC coating following the ion nitriding for 3 hrs comparing with the only DLC coated condition.

안정한 DLC 코팅에 의한 블레이드 옆면 마찰계수 감소가 다이아몬드마이크로 블레이드의 절삭성능과 내구성에 미치는 영향

장재철 ( Jae Cheol Jang ),김송희 ( Song Hee Kim ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.9

A DLC coating was deposited onto diamond micro-blades with Cu/Sn bond metal doped with WS2 and MoS2 as a solid lubricant to enhance the cutting efficiency. In comparison with blades without the DLC coating, the blades with the DLC coating showed a decreased specific wear rate in a ball-on-disc wear test and less momentary energy consumption in a dicing test. This is ascribed to reduction of the lateral friction coefficient with the work piece. A qualitative analysis of the reduction of momentary energy consumption was carried out to evaluate the effect of DLC coating on dicing performance. Chipping sizes of the diced workpiece surfaces were reduced by the DLC coating, which is beneficial for accurate machining.

라만 분광법을 활용한 마모 중 DLC 코팅의 구조적 변화 조사

김송희,장재철,Kim, Song-Hee,Jang, Jae Cheol 한국표면공학회 2019 한국표면공학회지 Vol.52 No.1

The structural change of DLC coatings during long-term wear test and dicing test under the low loading condition was investigated. DLC coatings were applied for the precision injection molds of a modified SNCM steel for the extension of life and the micro-diamond blades for the high cutting efficiency and the increase in life. A ball-on-disc wear tests in the mold steel and a dicing tests in the micro-diamond blades were conducted to understand degradation of DLC coatings. The degradation of DLC coatings for the injection mold steel and the micro-diamond blades during the wear and dicing tests were studied with Raman Spectroscopy. Raman peaks were divided two bands(D band and G band) to study the degradation process of DLC structure. By the wear test, polished condition of wear marks were observed to be maintained until 10 hrs of wear test period is given, but small striation marks appeared in 20 hours wear test. It was observed that $I_D/I_G$ ratios changed as the degradation of DLC coatings is proceeded during the wear tests and the dicing tests. It is suggested that the change in $I_D/I_G$ value possibly reflected from the composition of $sp^2$ and $sp^3$ bondings in DLC layers relevant to the change in mechanical and physical property.

감마선 조사전 홍삼 추출물의 투여가 생쥐 간에서의 Superoxide dismutase의 활성과 지질 과산화에 미치는 영향

박영순,김동윤,장재철,김동조,전철,Park, Yeong-Sun,Kim, Dong-Yun,Jang, Jae-Cheol,Kim, Dong-Jo,Jeon, Cheol 대한방사선치료학회 1992 大韓放射線治療技術學會誌 Vol.5 No.1

생쥐에 5.5mg의 홍삼추출물을 투여한 후 6.5Gy의 감마선을 전신 조사하여 생쥐 간에서의 항산화 효소들(Superoxide dismutase, Catalase, Peroxidase)의 활성도와 지질 과산화 수준의 변화를 측정 비교하여 이들의 상호 관련성과 인삼이 방사선 장해에 미치는 영향을 검토하였다. 방사선 조사로 인하여 SOD, Catalase 그리고 Peroxidase의 활성은 계속적으로 감소하였으나 홍삼추출물 투여군은 방사선 조사 후 21일에 생리적 식염수 투여군보다 Cu, Zn-SOD($40.7\%$), Mn SOD($26.9\%$), Catalase($20.0\%$) 그리고 Peroxidase($20.1\%$)의 활성이 증가되었으며, 또한 방사선 조사로 인하여 상승되는 지질 과산화의 함량이 억제되었다($70.5\%$). 이러한 결과는 인삼 성분이 방사선 조사로 인하여 생성이 촉진된 free radicals를 제거시킴으로서 지질 과산화물의 생성을 억제시켰거나 방사선에 의하여 손상된 기관들의 회복능력을 강화시킨 결과로 보이며 이는 인삼이 방사선 장해에 대하여 회복 또는 방호효과도 있음을 보여 주는 것이라 생각된다. Radioprotective effects of a red ginseng extracts on antioxidant enzymes(Superoxide dismutase, catalase and peroxidase) activities relationship to lipid peroxidation were studied in the cytosol fraction of mice liver. The experiments were carried out on Irradiated (5.5 Gy, $^{\60}Co$) and non-irradiated ICR mice after treatment of red ginseng extracts (5.5mg/mouse ; ip), In wholebody irradiated mice, irradiation caused a decrease in the activity of all these enzymes(on Day 21) The activities of SOD, Catalase and Peroxidase of red ginseng extracts treated mice were enhanced by $35.4\%,\;20.2\%$ and $20.1\%$, compared with non-treated mice. The red ginseng extracts led to inhibited increase of malondialdehyde product by ionizing radiation. The enhanced activity of enzymes that removed free radicals generated by radiation and thereby indicate that ginseng probably plays on important role in radioprotective effect.

청소년들의 스포츠활동 참여와 자아존중감 및 인터넷게임 중독성향의 관계

조영호(Cho Yeong-Ho),장재철(Jang Jae-Cheol) 한국체육과학회 2010 한국체육과학회지 Vol.19 No.1

In this study, hypothesis were established based on the results of previous studies, data of 454 youth's participants in sports were used for actual analysis, and hypothesis test was performed through analysis on the measurement of model fit as well as covariance of path coefficient in order to clarify relation among youth's participation grade in sports, self-esteem, and propensity to internet game addiction. The Findings of this study are as follows. Fist, there is positive relationship between youth's participation grade in sports and positive self-esteem. Second, there is negative relationship between youth's participation grade in sports and negative self-esteem. Third, there is negative relationship between Youth's positive self-esteem and propensity to internet game addiction. Fourth, there is positive relationship between youth's negative self-esteem and propensity to internet game addiction. Fifth, there is negative relationship between youth's participation grade in sports and propensity to internet game addiction.

사료 내 섬유소의 첨가가 자돈의 성장 성적에 미치는 영향

구성민,이에스더,이수협,장재철,Seong Min Koo,Esther Lee,Su Hyup Lee,Jae Cheol Jang 국립한국농수산대학교 교육개발센터 2024 현장농업연구지 = Journal of practical agricultural resear Vol.25 No.4

본 실험은 자돈 사료 내 섬유소 공급원 및 첨가 수준의 차이가 이유자돈의 성장 능력에 미치는 영향을 평가하고자 수행되었다. 섬유소 공급원으로 sugar beet pulp와 oat hull을 각 2%, 8% 첨가 수준을 달리하여 자돈에 급이하였으며, 처리구는 사료 내 항생제를 0.1% 첨가한 PC 처리구의 성장 성적에 비해 낮았으나, 항생제를 첨가하지 않은 NC 처리구에 비해 높게 나타났다. 또한 sugar beet pulp 8%를 급이 한 처리구는 PC 처리구와 유사한 성장 성적을 보였으며, 이는 섬유소 공급이 이유 후 자돈의 장내 환경에 긍정적 영향을 미친 것으로 사료된다. This study was undertaken to evaluate the effect of feeding with fiber diets on growth performance in weaned piglets. A total of 240 pigs with an averge weight of 8.69±0.45 kg at 28±2 days of age were allocated into a randomized complete block design (RCBD) with a total of 6 treatments and 5 replications per treatment in the pig barn. The experimental treatments were as follows: 1) Negative control (NC: Basal diet), 2) Positive control (PC: Basal diet+antibiotic), 3) SBP2 (Basal diet+2% sugar beet pulp addition), 4) SBP8 (Basal diet+8%diet+8% sugar beet pulp addition), 5) OH2 (Basal diet+2% sugar beet pulp), and 6) OH8 (Basal diet+8% oat hull addition). The pigs were fed phase I diets for 2 weeks and phase II diets for 3 weeks, with the average daily gain (ADG) and average daily feed intake (ADFI) measured on days 14 and 35. During 2 week the growth performance of the PC treatment, with 0.1% antibiotic addition, showed a significant increase (P<0.05). In 0~5 weeks, the growth performance in the PC treatment was the highest. Treatments with dietary fiber additions exhibited lower daily gains compared to the PC treatment but were higher than the NC treatment. SBP8, with 8% sugar beet pulp addition, showed growth performance comparable to the PC treatment (P<0.05). Additionally, the 8% fiber addition level demonstrated significantly higher daily gains compared to the 2% addition level (P<0.05). The addition of fiber to pig diets resulted in lower growth performance compared to treatments with antibiotic additions. However, the pigs fed SBP8 showed growth performance equivalent to those in the PC treatment, suggesting the potential of sugar beet pulp as a substitute for antibiotics in pig feed. The growth attributed to sugar beet pulp addition in the feed is speculated to occur while the immature gut of the pigs is developing and due to the positive influence of sugar beet pulp's fiber source on the gut environment.

홈 네트워크 기술개발 동향 및 산업화 전략

장동현(Dong-Hyun Jang),장재철(Jae-Cheol Jang),현종웅(Jong-Woong Hyun),김태근(Tae-Geun Kim) 한국정보과학회 2005 정보과학회지 Vol.23 No.2

원격탐사 기술 기반 위험·유해물질(HNS) 모니터링 기초 연구

박경애(Kyung-Ae Park),박재진(Jae-Jin Park),장재철(Jae-Cheol Jang),이문진(Moonjin Lee),김태성(Tae-Sung Kim) 한국해양환경·에너지학회 2018 한국해양환경공학회 학술대회논문집 Vol.2018 No.5

GK2A AMI를 이용한 한반도 식생건강지수 산출

이수진 ( Soo-jin Lee ),조재일 ( Jaeil Cho ),류재현 ( Jae-hyun Ryu ),김나리 ( Nari Kim ),김광진 ( Kwangjin Kim ),손은하 ( Eunha Sohn ),박기홍 ( Ki-hong Park ),장재철 ( Jae-cheol Jang ),이양원 ( Yangwon Lee ) 대한원격탐사학회 2022 大韓遠隔探査學會誌 Vol.38 No.2

지구온난화는 기후변화를 야기하며 전지구적으로 이상기상 현상을 유발하고 있다. 우리나라에서도 폭염, 가뭄과 같은 이상기상 현상이 증가하고 있는 상황이다. 이상기상 감시를 위하여 지표면온도(Land Surface Temperature, LST), 온도상태지수(Temperature Condition Index, TCI), 식생활력지수(Normalized Difference Vegetation Index, NDVI), 식생상태지수(Vegetation Condition Index, VCI), 식생건강지수(Vegetation Health Index, VHI) 등의 위성자료가 활용되고 있다. TCI와 VCI를 이용하여 계산되는 VHI는 온도, 강수와 같은 기상 요인에 의한 식생 스트레스를 나타내며, 기후변화 상황에서 가뭄 평가에 주로 활용되고 있다. TCI, VCI는 날짜 및 장소에 따른 LST, NDVI의 과거 평년치를 참조해서 산출되기 때문에, 아직 2년여의 자료밖에 없는 천리안위성 2A호(GK2A) AMI (Advanced Meteorological Imager) 자료로부터 TCI, VCI, VHI를 산출하는 것은 현재로서는 쉽지 않은 일이다. 본 연구에서는 대안적인 방법으로 VIIRS (Visible Infrared Imaging Radiometer Suite) 센서의 LST, NDVI를 이용하여 GK2A의 VHI 산출 가능성을 모색하였다. GK2A와 VIIRS의 LST, NDVI는 상당히 높은 상관성을 보이기 때문에, GK2A에 존재하지 않는 과거 평년치를 VIIRS 자료로 대체하는 방식을 택하였다. 8일 간격으로 GK2A 격자에 해당하는 LST, NDVI의 최소·최대값 조견표를 구축하여 TCI, VCI, VHI를 산출하였고, 최근 우리나라 이상기상 현상에 대한 해석을 수행하였다. GK2A VHI는 2020년 3월과 6월의 폭염, 4월과 7월의 저온, 8월의 폭우 등으로 인한 식생 스트레스의 변화를 잘 표현하는 것으로 나타났지만, 미국 해양대기청(National Oceanic and Atmospheric Administration, NOAA)의 VHI 산출물은 그렇지 않았다. 본 연구에서 제시한 GK2A VHI는 향후 LST, NDVI의 과거 평년치에 대한 통계적으로 엄밀한 보완을 거친다면 폭염, 가뭄으로 인한 식생 스트레스 감시에 활용될 수 있을 것으로 사료된다. Global warming causes climate change and increases extreme weather events worldwide, and the occurrence of heatwaves and droughts is also increasing in Korea. For the monitoring of extreme weather, various satellite data such as LST (Land Surface Temperature), TCI (Temperature Condition Index), NDVI (Normalized Difference Vegetation Index), VCI (Vegetation Condition Index), and VHI (Vegetation Health Index) have been used. VHI, the combination of TCI and VCI, represents the vegetation stress affected by meteorological factors like precipitation and temperature and is frequently used to assess droughts under climate change. TCI and VCI require historical reference values for the LST and NDVI for each date and location. So, it is complicated to produce the VHI from the recent satellite GK2A (Geostationary Korea Multi-Purpose Satellite-2A). This study examined the retrieval of VHI using GK2A AMI (Advanced Meteorological Imager) by referencing the historical data from VIIRS (Visible Infrared Imaging Radiometer Suite) NDVI and LST as a proxy data. We found a close relationship between GK2A and VIIRS data needed for the retrieval of VHI. We produced the TCI, VCI, and VHI for GK2A during 2020-2021 at intervals of 8 days and carried out the interpretations of recent extreme weather events in Korea. GK2A VHI could express the changes in vegetation stress in 2020 due to various extreme weather events such as heatwaves (in March and June) and low temperatures (in April and July), and heavy rainfall (in August), while NOAA (National Oceanic and Atmospheric Administration) VHI could not well represent such characteristics. The GK2A VHI presented in this study can be utilized to monitor the vegetation stress due to heatwaves and droughts if the historical reference values of LST and NDVI can be adjusted in a more statistically significant way in the future work.

위성자료와 기상모델자료를 이용한 AI 토양수분 격자자료 생산

이수진 ( Soo-jin Lee ),손은하 ( Eunha Sohn ),박기홍 ( Ki-hong Park ),장재철 ( Jae-cheol Jang ),이양원 ( Yangwon Lee ) 한국물환경학회 2022 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2022 No.-