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한지훈,전중환,김동주,장홍희,구자민,김영기,이스캇,김은정,이희천,이효종,연성찬,Han, Ji-hoon,Jeon, Jung-hwan,Kim, Dong-joo,Chang, Hong-hee,Koo, Ja-min,Kim, Young-ki,Lee, Scott-s,Kim, Eun-jung,Lee, Hee-chun,Lee, Hyo-jong,Yeon, Seong-chan 대한수의학회 2005 大韓獸醫學會誌 Vol.45 No.2
This study was carried out to find out how space allowance affect the social behavior of Korean native cattle (Bos taurus coreanae) steers. Twelve Korean native cattle (Bos taurus coreanae) steers were used as subjects, each of which was 30-month-old and observation period was from June to July 2003. Five (T1) and seven (T2) steers were allotted to two pens of $5m{\times}10m$ in a building with slate roof and open sides respectively. They were fed at 09:00 h and 16:00 h, twice a day. The behaviors of steers were recorded from 06:00 h to 17:00 h, using two color CCD cameras (Samsung SDC-411, Korea), one B/W CCD cameras (Samsung SBC-340, Korea), one multiplexer (Samsung SDM-081, Korea) and a time lapse VCR (Samsung SRV-30, Korea). The behaviors of each steer were recorded every 2 min using an instantaneous point sampling method. While the mean percentage of time budget in WA of T1 was lower than that of T2 (p<0.05), the mean percentage of time budget in SF of T1 was higher than that of T2 (p<0.05). When it gets hot, steers in T1 rested from 10:00 h to 14:00 h when it gets cool, showing 40~80% of LD rate while steers in T2 rested from 12:00 h, when it very hot to 17:00 h, showing 20~50% of LD rate, which is relatively low. Steers in T1 were fed from 06:00 h to 08:00 h when it was cool and from 16:00 h to 18:00 h, showing 20~45% of EA rate while steers in T2 were fed from 08:00 h to 14:00 h when it was hot, showing 25~50% of EA rate. In conclusion, it turned out that the number of steers affected their social behavior, and T1 was better environment than T2 in terms of welfare.
한지훈,사혜지 서울대학교 교육연구소 2022 Asia Pacific Education Review Vol.23 No.3
This study examines the current state of acceptance of online classes using the technology acceptance model. The background of the study is the turning point in Korean education in response to the COVID-19 pandemic and speculation about changes in the post-COVID educational environment. To measure the acceptance rate of online classes, a survey was conducted on a total of 313 university students taking online classes. The data were analyzed using structural equation modeling. The results of the study are as follows: First, the perceived ease of use of online classes showed a positive effect on perceived usefulness. Second, both the perceived ease of use and usefulness of online classes showed a positive effect on educational satisfaction. Third, both the perceived usefulness and satisfaction showed a positive effect on the acceptance intention of online education. However, the perceived ease of use did not have a positive effect on acceptance intention. These results suggest that satisfaction with online education can be further improved by developing online classes that are easy to use, focusing on the features that are frequently used by university students. In addition, universities should continuously provide training and advice to increase students’ perceived usefulness of online classes.
Improved Network Formation in Polyelectrolyte Complex Hydrogels via Suppression of Micellization
한지훈,김연수 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Physical hydrogels composed of oppositely charged polyelectrolytes have unique functions like sol-gel transition and self-healing. However, it is difficult to obtain both of high water content and excellent mechanical properties in the physical hydrogel. Generally, physical hydrogels can be easily obtained by using ABA triblock copolymers, where A blocks are charged blocks and B blocks are hydrophilic neutral blocks. At critical gelation concentration, ABA triblock copolymers construct a 3-dimensional polymer network through self-assembled micelles, especially flower-type micelles. In this case, the loop-shaped polymers do not contribute to connection of network at all, which lowers the efficiency of gel formation. Here, we propose new BABAB pentablock copolymers showing direct network formation rather than loop formation through suppression of micellization. The mechanism of the directly formed polymer network as well as the rheological properties of our hydrogels will be discussed.
한지훈,Eui-Kyung Jang,기미란,손려강,Seok Kim,Youngson Choe,백승필,정성욱 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.112 No.-
This paper reports the hydrothermal synthesis and characterization of poly(acrylic acid)-calcium phosphatepassivated TiO2 nanoparticles (TiO2@PAA-CaP NPs). The efficient loading and release of doxorubicin(DOX) from the TiO2@PAA-CaP NPs was observed at pH = 7.4 and 5.2, respectively. The loading andencapsulation amount of DOX in TiO2@PAA-CaP NPs was approximately fifteen and eight times as largeas that of unfunctionalized TiO2 NPs, respectively, suggesting the PAA-CaP passivation layer enhanced theinteraction between DOX and TiO2@PAA-CaP NPs. The DOX-loaded TiO2@PAA-CaP (TiO2@PAA-CaP(DOX))NPs exhibited much faster cumulative DOX release at acidic pH = 5.2 than at neutral pH = 7.4 because ofthe pH-responsive dissolution properties of the PAA-CaP passivation layer. TiO2@PAA-CaP(DOX) NPsshowed higher cytotoxicity towards MCF-7 tumor cells than free DOX. Confocal fluorescence microscopyand flow cytometry confirmed the enhanced cellular uptake of TiO2@PAA-CaP(DOX) NPs followed by theintracellular release of DOX. Overall, TiO2@PAA-CaP(DOX) NPs demonstrated significantly higher totalcytotoxicity towards MCF-7 tumor cells under UV-A irradiation, which was attributed to a synergisticeffect between efficient DOX delivery and enhanced photoinduced reactive oxygen species (ROS) generation. This study provides a facile means of synthesizing TiO2-based multifunctional nanocarriers withpH-responsive drug delivery and ROS generation essential for high efficacy therapeutic applications incancer treatments.
형상 변화에 효율적 대응을 위한 전이학습 기반 물리 정보 신경망의 하이퍼 파라미터에 따른 성능 분석
한지훈,최의진,홍선기 대한전기학회 2023 전기학회논문지 Vol.72 No.10
One of the most time-consuming parts of designing an electrical device is optimizing the geometry. Optimization involves fine-tuning dimensions such as slot widths and airgap lengths from a base geometry to meet user needs. FEA(Finite Element Analysis) is typically used to verify this performance. However, conventional FEA requires a separate analysis if the analysis geometry is varied even slightly. This causes a very long time consumption, and a transfer learning-based PINN(Physics-Informed Neural Network) is proposed to solve this problem. Since PINNs are at the basic level worldwide, their performance is analyzed according to hyper-parameters such as model parameters (e.g. weights or biases), preprocessing methods, activation functions, and the number of training data to increase their performance. Based on the analyzed hyper-parameters, the performance of the transfer learning-based PINN is verified under the condition of varying the airgap length of the E-I core.
Process design and environmental analysis for catalytic production of gamma-valerolactone from Kenaf
한지훈,Myungsuk Son,강동성 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-
Previous studies have suggested to report the effectiveness in an economically viable insight of generationof gamma-valerolactone (GVL) from non-food biomass resources, but the environmental performancehas less been conducted. When a new biorefinery process is presented for production of GVLfrom non-food biomass resources, environmental performances including carbon dioxide emission willbe improved compared to the conventional production approaches. This study designs the moreenvironmentally-friendly GVL process and expands to a LCA framework for the use of non-food biomassderived GVL as a product and solvent. To examine Kenaf utilization as a non-food biomass on GVL prodcution,this study focuses on process design and life cycle assessment (LCA) to indentify the global warmingpotentials (GWP) and fossil resource scarcity (FRS) of GVL production. The GWP and FRS results ofKenaf-based GVL were estimated to 1.326 kg CO2 eq. and 0.513 kg oil eq. of pure GVL. The LCA hasbeen conducted in consideration of Kenaf growth farmland and biorefinery construction site located inJeollabuk-do in South Korea.