의과대학/의학전문대학원 학생들의 학습에 대한 신념

박재현,Park, Jaehyun 연세대학교 의과대학 2012 의학교육논단 Vol.14 No.2

Learning in medical school is usually regarded as a very specialized type of learning compared to that of other academic disciplines. Medical students might have general beliefs about their own learning. Beliefs about learning have a critical effect on learning behavior. There are several factors that affect medical students' learning behavior: epistemological beliefs, learning styles, learning strategies, and learning beliefs. Several studies have addressed epistemological beliefs, learning styles, and learning strategies in medical education. There are, however, few studies that have reported on medical students' beliefs about learning. The purpose of this study was to determine what learning beliefs medical students have, what the causes of these beliefs are, and how medical educators teach students who have such beliefs. In this study, the five learning beliefs are assumed and we considered how these beliefs can affect students' learning behaviors. They include: 1) medical students are expected to learn a large amount of information in a short time. 2) memorization is more important than understanding to survive in medical schools. 3) learning is a competition and work is independent, rather than collaborative. 4) reading textbooks is a heavy burden in medical education. 5) the most effective teaching and learning method is the lecture. These learning beliefs might be the results of various hidden curricula, shared experiences of the former and the present students as a group, and personal experience. Some learning beliefs may negatively affect students' learning. In conclusion, the implications of medical students' learning beliefs are significant and indicate that students and educators can benefit from opportunities that make students' beliefs about learning more conscious.

NVDIMM의 동작 특성 분석 및 개선 방안 연구

박재현,이형규,Park, Jaehyun,Lee, Hyung Gyu 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.3

High performance non-volatile memory system can mitigate the gap between main memory and storage. However, no single memory devices fulfill the requirements. Non-volatile Dual In-line Memory Module (NVDIMM) consisted of DRAMs and NAND Flashes has been proposed to achieve the performance and non-volatility simultaneously. When power outage occurs, data in DRAM is backed up into NAND Flash using a small-size external energy storage such as a supercapacitor. Backup and restore operations of NVDIMM do not cooperate with the operating system in the NVDIMM standard, thus there is room to optimize its operation. This paper analysis the operation of NVDIMM and proposes a method to reduce backup and restore time. Particularly, data compression is introduced to reduce the amount of data that to be backed up and restored. The simulation results show that the proposed method reduces up to 72.6% of backup and restore time.

압축 기반 상변화 메모리 시스템에서 저장 위치를 고려한 하이브리드 SLC/MLC 관리 기법

박재현,이형규,Park, Jaehyun,Lee, Hyung Gyu 대한임베디드공학회 2016 대한임베디드공학회논문지 Vol.11 No.2

Density of Phase-Change Memory (PCM) devices has been doubled through the employment of multi-level cell (MLC) technology. However, this doubled-capacity comes in the expense of severe performance degradation, as compared to the conventional single-level cell (SLC) PCM. This negative effect on the performance of the MLC PCM detracts from the potential benefits of the MLC PCM. This paper introduces an efficient way of minimizing the performance degradation while maximizing the capacity benefits of the MLC PCM. To this end, we propose a location-aware hybrid management of SLC and MLC in compressed PCM main memory systems. Our trace-driven simulations using real application workloads demonstrate that the proposed technique enhances the performance and energy consumption by 45.1% and 46.5%, respectively, on the average, over the conventional technique that only uses a MLC PCM.

천연물 추출물이 대식세포 및 호염구 활성 억제에 미치는 영향

박재현,장지민,차상률,백효신,이주연,이유희,류세민,양세란,Park, Jaehyun,Jang, Jimin,Cha, Sang-Ryul,Baek, Hyosin,Lee, Jooyeon,Lee, You-Hui,Ryu, Semin,Yang, Se-Ran 한국식품위생안전성학회 2022 한국식품위생안전성학회지 Vol.37 No.3

Asthma is a chronic inflammatory disease characterized by recurring symptoms, airflow obstruction, and bronchial hyper-responsiveness. The onset of asthma for most patients begins early in life, and current asthma treatment with anti-inflammatory agents can have adverse effects, eventually leading to impaired quality of life. In the pathogenesis of asthma, macrophages and basophils play a vital role during progression. Macrophages not only induce inflammation by secreting inflammatory cytokines but also promote DNA damage and mucus production through nitric oxide (NO) production. Basophils enhance eosinophil recruitment and aggravate asthma through the FcεRIα receptor with high affinity for histamine and IgE. Therefore, in this study, we investigated whether the activation of macrophages and basophils is suppressed by the individual extracts of 28 natural products. RAW 264.7 cells (mouse macrophages) were treated with the natural products in LPS, and 4 natural product extracts resulted in decreased NO production. In β-hexosaminidase assay using RBL-2H3 cells (rat basophils), 19 natural product extracts decreased β-hexosaminidase production. In NO production and β-hexosaminidase assay using macrophages and basophils, 3 natural product extracts (Plantago asiatica, Centella asiatica, and Perilla frutescens var. japonica) significantly inhibited NO production and β-hexosaminidase release. Overall, we examined the inhibitory effects of 28 natural product extracts on macrophage and basophil activity, and the findings demonstrated the potential of natural product extracts for treating asthma and macrophage- and basophil-related diseases.

기후변화에 따른 R-Factor 값을 고려한 토양 유실량 평가

박재현,김동주,김민규,장춘화,강현우,금동혁,임경재,Park, Jaehyun,Kim, Dongju,Kim, Minkyu,Jang, Chunhwa,Kang, Hyunwoo,Kum, Donghyuk,Lim, Kyoung 한국관개배수위원회 2014 한국관개배수논문집 Vol.21 No.1

This study evaluated the soil loss considering the R-Factor value following the climate change. To calculate the soil loss of the basin in Jaun-ri, Hongcheon-gun which is the study area, the future climate change scenario and convenience revision were used to build the past 30 years, future 30 years R-Factor and it was applied to USLE model. As a result, as the R-Factor value declined a little in the future, the soil loss was also reduced but it corresponds to the 'very high' according to the OECD soil loss grade so the solution to reduce the soil loss is necessary and it can be used for another study material.

PZT 파우더 첨가에 따른 티타늄 파우더/폴리머 콘크리트 복합재료의 진동 특성 및 압축 물성 분석

박재현,김석룡,김경수,김건,김석호,이범주,정안목,안종욱,김선주,이시맥,유형민,Park, Jaehyun,Kim, Seok-Ryong,Kim, Kyoung-Soo,Kim, Geon,Kim, Seok-Ho,Lee, Beom-Joo,Jeong, Anmok,An, Jonguk,Kim, Seon Ju,Lee, Si-Maek,Yoo, Hyeong-Min 한국복합재료학회 2022 Composites research Vol.35 No.3

In this study, Ti powder/Polymer concrete composites were processed by adding the PZT powder, one of the piezoelectric materials, to improve the vibration damping effect of Polymer concrete. Ti powder was added at a constant ratio in order to maximize the vibration damping effect using the piezoelectric effect. Three types of composite material specimens were prepared: a specimen without PZT powder, specimens with 2.5 wt% and 5 wt% of PZT powder. The vibration characteristics and compression properties were analyzed for all specimens. As a result, it was confirmed that as the addition ratio of PZT powder increased, the Inertance value at the resonant frequency decreased due to the piezoelectric effect when the vibration generated from Ti powder/polymer concrete was transmitted. Especially, the Inertance value was decreased by about 19.3% compared to the specimen without PZT at the resonant frequency. The change in acceleration with time also significantly decreased as PZT powder was added, confirming the effect of PZT addition. In addition, through the compression strength test, it was found that the degree of deterioration in compression properties due to the addition of PZT up to 5 wt% was insignificant, and it was confirmed that the powder was evenly dispersed in the composites through the cross-sectional analysis of the specimen.

화물열차 평균 입환 소요시간 분석

박재현(Jaehyun Park),권용장(Yongjang Kwon),김경태(Kyoungtae Kim),한광희(Kwanghee Han) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.5

열차가 정차역 또는 조차장에서 열차를 연결 또는 분리하는 작업 일체를 입환이라고 하는데, 화물열차는 입환으로 인해 중간역이 착발 또는 환적의 기능을 가능하게 하여 수송경로를 다양하게 구성할 수 있는 장점이 되지만, 한편으로는 철송의 속도를 크게 저하하는 요인이기도 하다. 입환에 소요되는 시간은 정차역의 조건, 작업 내용, 신호대기 여부에 따라 크게 좌우되므로 화물열차의 정확한 입환 소요시간을 예측하기는 어렵다. 본 연구는 개별 화차의 운행기록 자료를 토대로 입환으로 인한 시종점간 손실시간 분석을 통해, 입환에 소요되는 평균 시간을 분석하였다. 이 평균 입환 소요시간은 현재 정차역의 입환작업 효율성 평가 및 향후 화물열차 운행형태 개선, 화물역의 시설 개량 등 의사결정을 위한 거시적 효과분석의 대표값으로 적용될 수 있을 것으로 기대된다. Shunting is a process of assembling each train cars in a station or in a switchyard, in order to composite a trainset before being deployed into operation. Shunting particularly enables freight trains to load/unload freights in the intermediate stations, which provides flexibility of determining hauling routes in logistics. On the other hand, shunting works in the middle of service increase the overall travel time. The time required for shunting process varies with station condition such as track wiring, work schedule, train density and so forth. Thus it is difficult to predict the time lose by shunting. This study attempts to calculate the average shunting time by analyzing the operation record of individual freight cars by comparing total travel time of trains with or without shunting works. This average value found here expects to be used in assessment of efficiency for a freight station or helps decision making of an improvement plan for the railroad logistics.

3D 프린터 마이크로채널 제작 및 액상 물의 압력강하 특성에 관한 연구

박재현(Jaehyun Park),박희성(Heesung Park) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.1

마이크로채널은 단위체적당 표면적비가 높기 때문에 컴퓨터 마이크로 프로세서 냉각, 정밀 화학분석 및 바이오 분야로의 응용이 다양하게 적용 될 수 있어 많은 연구가 진행 중이다. 본 연구에서는 3D 프린터를 이용하여 사각 마이크로채널을 제작하였고, 실험에서 마이크로채널을 통과하는 액상 물은 탈이온수를 사용하여 유량변화에 대한 압력강하를 측정하였다. 마이크로채널의 크기는 161 μm에서 664 μm로 변화시켜 제작하였으며, 유동의 레이놀즈 수는 16<Re <1000의 범위에서 압력변화를 측정하였다. 마이크로채널의 단면을 절단한 후 전자현미경으로 관찰한 결과 형상이 직사각형의 형태에 매우 근접한 것을 볼 수 있었다. 또한 유체유동의 특성은 전통적인 유체역학의 이론과의 차이를 나타내었으나 최근의 마이크로채널 유동과 연관된 연구와는 유사하게 측정되었다. 본 연구결과 3D프린터를 이용한 사각 마이크로채널의 제작과 이를 유동특성 실험에 적용 가능하다. The validity of friction factor theory, based upon conventional-sized passages for microchannel flows, is an active area of research. The high surface to volume ratio of a microchannel offers many advantages over macroscale devices and processes. This study focused on the laminar flow (16<Re<1000) within rectangular microchannel. The hydraulic diameter was from 161μm to 664μm for single-phase liquid flow. A controllable syringe pump was used to provide flow while a differential pressure transducer was used to record the pressure drop. These results demonstrated that a 3D printer can drastically simplify custom microchannel fabrication and still support complex features, which are typically only accessible with advanced fabrication techniques.

서울 청계천 선형공원의 유니버설디자인 특성 연구

박재현(Park, Jaehyun),이연숙(Lee, Yeunsook) 한국생태환경건축학회 2016 한국생태환경건축학회 학술발표대회 논문집 Vol.16 No.1

수입 팜기름과 카놀라기름의 국내에서의 산업적 탈색과 탈취에 따른 산화관련 특성과 벤조피렌 함량

박재현(Jaehyun Park ),최은옥(Eunok Choe) 한국식품과학회 2017 한국식품과학회지 Vol.49 No.6

수입 팜기름과 수입 후 탈산한 카놀라기름은 110에서 80분동안 산성백토(1%)를 이용한 탈색과 250oC, 3 torr에서 3시간 동안의 탈취공정을 거치면서 토코페롤 함량이 감소하였음에도 불구하고 산값과 산화물값의 감소와 함께 산화 관련 특성은 개선되었으며, 탈취보다는 탈색공정에 의한 개선 효과가 높았다. 탈취공정은 기름의 비정상 향미화합물을 대부분 제거하였으며, 고온에서의 탈색과 탈취공정에도 불구하고 위해 화합물인 벤조피렌 함량에 유의한 증가를 보이지 않았다. 따라서 본 결과는 국내 정제 공정에서 수입 팜기름과 카놀라기름의 품질 개선에 탈취보다는 탈색이 큰 영향을 나타냄을 제시하였다. Effects of bleaching and deodorization on the quality of imported palm and canola oils were evaluated. Imported palm oil and deacidified canola oil were bleached with acid clay, followed by deodorization. Oxidation-related quality was evaluated by determining fatty acid composition by GC, acid and peroxide values, induction period by Rancimat, and offflavor compounds by GC-MS. Tocopherols and benzo(a)pyrene were analyzed by HPLC. Acid and peroxide values were decreased by bleaching and deodorization, and tocopherol content was decreased to 60-70% (p<0.05). Aldehydes were major off-flavor compound class of imported oils, most of which were removed after deodorization. No significant change was observed in benzo(a)pyrene content (~0.4 μg/kg) of both oils by bleaching and deodorization (p>0.05). The oxidationrelated quality of palm and canola oils was more improved after industrial bleaching than by deodorization. These results suggest that a careful control of bleaching during domestic refining can improve the quality of palm and canola oils.