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글로벌 압력의 배경에서 미국의 표준교육 개혁 동향: 교육과정 표준화 징후
오정환 ( Junghwan Oh ),임태홍 ( Taehong Lim ),정구인 ( Kooin Jung ) 한국교육과정학회 2021 교육과정연구 Vol.39 No.1
This article describes how the United States (U.S.) responded the pressure of global educational governance that has derived from an increased emphasis on international comparisons of student performance since the 1980s and critically discusses the issue of curriculum standardization that emerged in the implementation of standards-based reform (SBR). Education policies intended to yield greater national consistency in curricula are a global trend with multiple countries centralizing curricula and assessments. In this global context, the U.S. introduced the concept of broadly described standards due to their distinctive national policy features, including sociocultural complexity, regional diversity, and polyphonic federalism. The school curriculum in the U.S., however, tends to be standardized as the federal role in education is expanded with the implementation of SBR. Total standardization of school curricula does not seem to be desirable in light of the system diversity, sociocultural disparities, and regional differences. It would prompt multiple ideological issues such as the resistance of local entities, the renewal of divisions and segregation among groups of pupils, and a hegemony of knowledge. Expansive discourses and cooperative efforts among multiple levels of authority are needed to reduce the potential movement to curriculum standardization and establish socioculturally and locally responsive standards learning contexts.
CCSS 개혁이 미국의 체육교과 교육과정에 미친 영향 : 교육과정 표준화 동향
오정환(Oh, Junghwan),박재호(Park, Jae-Ho),박석(Park, Sok) 한국체육과학회 2021 한국체육과학회지 Vol.30 No.3
This paper describes the development of Common Core State Standards (CCSS) that has emerged in the backdrop of global educational governance, examining how CCSS influenced the school-based physical education (PE) curriculum in the United States (US). Since the new millennium, states have adopted CCSS as part of standards-based reform with the aim of offering local entities both educational flexibility and consistency. After the implementation of CCSS, however, the school curriculum in the US tends to be standardized focusing on the CCSS system due to an increased influence of the federal government. In this national context, the profession of PE has made multifaceted efforts to address this nationwide reform movement by establishing national standards and summative teacher guidelines, grade-level outcomes, and assessment systems, thereby building a unified common foundation in the field. Such system-wide change, however, does not necessarily signal total standardization for PE curricula. Expansive discourses and debates among professionals in the field have exerted significant limits on curriculum standardization. This implies that although policies for K-12 PE have been assembled focusing on the CCSS movement, the implementation in local programs remains distinct in form and scope due to multiple unique features of each program.
오정환(Junghwan Oh) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
We investigate capability of Magneto-Motive Ultrasound (MMUS) to detect superparamagnetic iron oxide (SPIO) nanoparticles (core diameter~5㎚) taken up by liver macrophage cells. MMUS system was tested by combining a high strength magnetic field with ultrasound. Magnetic force acting on SPIO was varied by applying a sinusoidal current to a solenoid containing a conical iron core that substantially increased and focused the magnetic field strength (B<SUB>max</SUB>=2 Tesla). Results of our experiments indicate that ultrasound combined with magneto-motive excitation is a candidate imaging modality to identify magnetic nanoparticles for ultrasound molecular imaging.
안민우,오정환,강현욱,Ahn, Minwoo,Nguyen, Van Phuc,Oh, Junghwan,Kang, Hyun Wook 대한의용생체공학회 2014 의공학회지 Vol.35 No.3
The purpose of the study was to identify the effect of laser parameters on photocoagulation to maximize safety and efficacy during varicose vein treatment. CW and pulsed modes at 1470 nm were initially compared as a function of power on bovine liver tissue. In the pulsed mode, various parameters including repetition rate, duty cycle, and irradiation time were compared to evaluate tissue response during thermal treatment. The results demonstrated that CW and pulsed modes yielded almost similar coagulation development possibly due to shorter irradiation time of 5 sec. Regardless of laser mode, both repetition rate and duty cycle presented constant coagulation rate whereas longer irradiation time facilitated coagulation process.
강현욱,오정환,Kang, Hyun Wook,Oh, Junghwan 한국광학회 2012 한국광학회지 Vol.23 No.3
In this paper, two wavelengths mainly used for laser prostatectomy have been quantitatively compared: 532 and 980 nm. Two lasers at 40 W were employed to ablate bovine liver in vitro. Ablation performance was evaluated in light of number of sweeps, ablation volume, and coagulative necrosis. 532 nm yielded up to four times higher ablation efficiency than 980 nm. Regardless of wavelength, ablation rate per sweep decreased with the number of sweeps. 532 nm generated relatively deeper ablation craters along with thinner coagulation whereas 980 nm created superficial tissue ablation with up to 2 mm thick coagulative necrosis. Due to higher light absorption and effective thermal confinement, 532 nm induced more efficient tissue ablation with a smaller coagulative necrotic zone. The current study demonstrated that 532 nm could be a more ideal wavelength for laser prostatectomy, and the future in vivo investigations will confirm these findings. 본 논문에서는 전립선 비대증 환자 치료 시 조직 제거에 사용되는 두 파장들을 비교 연구하였다. 가시광선 영역인 532 nm는 혈액 속의 헤모글로빈에 의한 흡수율이 높은 반면, 근적외선 영역인 980 nm는 물에 의한 빛의 흡수율이 높다. 동물의 간 조직을 각각의 레이저를 이용하여 40 W 출력에서 제거하였으며, 조직 제거율을 제거 횟수, 제거 부피, 열손상 정도를 통해 검사하였다. 532 nm의 경우 높은 레이저 흡수율로 인해 조직 제거율이 980 nm 보다 4배까지 증가하였으며, 열손상은 상대적으로 약 30%까지 낮게 나타났다. 파장에 관계없이 제거 횟수가 높을수록 단위 횟수당 제거율이 낮아졌으며, 이는 레이저 빛이 거리에 따라 발산함과 동시에 제거된 조직의 입자들이 먼지 방해 현상을 일으킴으로써 효율의 저하를 일으켰음을 짐작할 수 있었다. 보다 효율적인 열적 제한 상태와 높은 흡수율로 인해 가시광선 영역의 532 nm가 근적외선 980 nm 보다 전립선 치료에 있어서 더욱 효율적인 파장임을 알 수 있었으며, 이러한 발견을 전임상 및 임상을 통해 확인할 계획이다.
광간섭 단층 촬영 장치와 광음향 현미경의 결합을 통한 동시 이미지 획득 연구
김세희,이창호,한승훈,강현욱,오정환,김지현,김철홍,Kim, Sehui,Lee, Changho,Han, Seonghoon,Kang, Hyun Wook,Oh, Junghwan,Kim, Jeehyun,Kim, Chulhong 대한의용생체공학회 2013 의공학회지 Vol.34 No.2
In this study, we developed an integrated optical coherence tomography - photoacoustic microscopy (OCT-PAM) system to simultaneously provide optical absorption and scattering information. Two different laser sources, such as a pulsed laser for PAM and a superluminescent diode for OCT, were employed to implement the integrated OCT-PAM system. The performance of the OCT-PAM system was measured by imaging carbon fibers. We then imaged black and white hairs to demonstrate the simultaneous OCT-PAM imaging capabilities. As a result, OCT can produce 3-D images of both black and white hairs, whereas PAM is only able to image the black hair due to strong optical absorption of black hair.
광음향 영상화를 위한 PMN-PZT 바늘형 수중청음기 제작
하강렬,김무준,강현욱,오정환,Ha, Kanglyeol,Kim, Moojoon,Kang, Hyun Wook,Oh, Junghwan 한국음향학회 2016 韓國音響學會誌 Vol.35 No.3
수 MHz의 초음파를 이용하는 저주파 광음향 영상장치에 적용하는 것을 목적으로 압전단결정 PMN-PZT를 사용한 바늘형 수중청음기를 설계 제작하고, 그 특성을 수신감도가 알려져 있는 상용 PVDF(Polyvinylidene Fluoride) 수중청음기와 비교하여 평가하였다. 설계한 수중청음기의 임펄스응답을 KLM 모델에 의해 시뮬레이션한 결과, $50{\Omega}$의 종단 임피던스에 걸리는 최대 전압을 기준으로 한 수신감도는 -261.6 dB re $1V/{\mu}Pa$이며, 2 ~ 12 MHz 대역에서 5 dB 이내의 비교적 평탄한 특성을 가지는 것으로 예측되었다. 제작한 수중청음기의 수신감도를 순음 펄스를 사용하여 측정한 결과, 측정 가능한 2 ~ 8 MHz 대역에서 상용의 수중청음기에 비해 평균 10.9 dB 높게 나타났으며, 그 값은 $-255.8{\pm}2.8$ dB re $1V/{\mu}Pa$이었다. 나아가, 제작한 수중청음기를 기계주사형 광음향 영상장치에 적용하여 머리카락에 대한 영상을 획득하였는바, 수신된 광음향 신호가 상용의 것보다 크고, 영상 또한 우수함을 알았다. For application to several MHz photoacoustic imaging systems, a needle hydrophone was designed and fabricated by using PMN-PZT piezoelectric single crystal, and its characteristics were evaluated through comparison with a commercial PVDF(Polybinylidene Fluoride) hydrophone of which receiving sensitivity is known. The simulation using the KLM model results show that the peak receiving impulse response for $50{\Omega}$ terminating impedance of the fabricated hydrophone is -261.6 dB re $1V/{\mu}Pa$ and the frequency response is relatively flat over 2 ~ 12 MHz with fluctuation less than 5 dB. The measurement results using tone burst signals also show that it has higher (ave. 10.9 dB) sensitivity than the commercial hydrophone in 2 ~ 8 MHz, and the receiving sensitivity of $-255.8{\pm}2.8$ dB re $1V/{\mu}Pa$ was measured for the fabricated hydrophone. In addition, it is known that the photoacoustic signals and the image of a hair obtained by a mechanical scanned photoacoustic imaging system with the fabricated hydrophone were bigger and better than those obtained with the commercial hydrophone.