• International Journal of Advanced Culture Technology
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• 제9권1호
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• pp.162-167
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• 2021

The aim of this paper is to analyze the development of effective online Problem-Based Learning (PBL) and Project-Based Learning (PjBL). The collaborative PBL/PjBL become one of the hot issues with the rapid growth of online learning in the era of COVID-19. Educators try to get innovative to continue instruction without sacrificing student engagement, thus adopting an instructional model of PBL/PjBL. The PBL process involves clarifying terms, defining complex problems, brainstorming, structuring and hypothesis while PjBL includes project-planning, implementation, communicating the results of a project in a presentation and evaluations with immediate individually tailored feedback within a predetermined period. Despite the differences between online and offline learning, the benefits of learning online or offline are practically the same if enough bidirectional interactions between instructors and students are possible. We argue that online qualifications are just the same as those of offline ones in PBL/PjBL models, therefore, the standards of online/offline learning are identical since education is a two-way communication.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.286-292
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• 1993

The classical way to improve the control performance is studied on the aspects of gun/turret deive systens. Two ways are discussed comparadively ; electrical case and electro-hydraulic case. System parameters are analytically studied in terms of resonance frequencies, and damping and gear train ratio effects are checked in relation to resonance frequency increase. Benefit of the feedback is discussed to increase the damping of the natural frequency lending to bandwidth increase.

• 상하수도학회지
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• 제26권3호
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• pp.383-397
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• 2012

In this study, a System Dynamics (SD) simulation model for the efficient operations of an industrial water supply system was developed by investigating the feedback loop mechanisms involved in the operations of the system. The system was modeled so that as demand is determined the water supply quantity of intake pumping stations and dams are allocated. The main feedback loop showed that many variables such as the combinations of pump operation, unit electric power(kWh/$m^3$), unit electric power costs(won/$m^3$), water level of water way tunnel, suction pressure and discharge of pumping station, and tank and service reservoir water level had causal effects and produced results depending on their causal relationship. The configurations of the model included an intake pumping station model, water way tunnel model, pumping station model (including the tank and service reservoir water level control model), and unit electric power model. The model was verified using the data from the case study industrial water supply system that consisted of a water treatment plant, two pumping stations and four dams with an annual energy costs of 5 billion won. It was shown that the electric power costs could have been saved 7~26% during the past six years if the operations had been based on the findings of this study.

• 전자공학회논문지SC
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• 제37권1호
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• pp.30-39
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• 2000

비선형 시스템의 선형화 문제는 좌표변환만에 의한 것과 좌표변환과 상태 궤환에 의한 것 등 크게 두 가지로 나눌 수 있다. 본 논문에서는 다 입력 이산 비선형 시스템에 대하여 이 두 가지 문제에 대한 필요충분 조건을 얻는다. 또한, 선형화하는 좌표변환과 궤환을 구하는 방법을 증명과정에서 제시한다.

• 시스템엔지니어링학술지
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• 제19권2호
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• pp.46-58
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• 2023

Deterministic safety analysis is a crucial part of safety assessment, particularly when it comes to demonstrating the safety of nuclear power plant designs. The traditional approach to deterministic safety analysis models is to model the nuclear core using point kinetics. However, this simplified approach does not fully reflect the real core behavior with proper moderator and fuel reactivity feedbacks during the transient. The use of Multi-Physics approach allows more precise simulation reflecting the inherent three-dimensionality (3D) of the problem by representing the detailed 3D core, with instantaneous updates of feedback mechanisms due to changes of important reactivity parameters like fuel temperature coefficient (FTC) and moderator temperature coefficient (MTC). This paper addresses a CEA ejection accident at hot full power (HFP), in which the underlying strong and un-symmetric feedback between thermal-hydraulics and reactor kinetics exist. For this purpose, a multi-physics analysis tool has been selected with the nodal kinetics code, 3DKIN, implicitly coupled to the thermal-hydraulic code, RELAP5, for real-time communication and data exchange. This coupled approach enables high fidelity three-dimensional simulation and is therefore especially relevant to reactivity initiated accident (RIA) scenarios and power distribution anomalies with strong feedback mechanisms and/or un-symmetrical characteristics as in the CEA ejection accident. The Systems Engineering approach is employed to provide guidance in developing the work in a systematic and efficient fashion.

• 한국재료학회지
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• 제13권8호
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• pp.485-490
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• 2003

We have developed a new way of the constant growth technique to maintain a grating height of originally-etched V-groove of submicron gratings up to 1.5 $\mu\textrm{m}$ thickness by a low pressure metalorganic chemical vapor deposition. The constant growth technique is well performed on two kinds of submicron gratings that made by holography and electron (e)-beam lithography GaAs buffer layer grown on thermally deformed submicron gratings has an important role in recovering the deformed grating profile from sinusoidal to V-shaped by reducing mass transport effects. The thermal deformation effect on submicron gratings made by e-beam lithography is less than that on submicron gratings made by holography. The constant growth technique is an important step to realize complex optoelectronic devices such as one-step grown distributed feedback lasers and two-dimensional photonic crystals.

• 한국환경과학회지
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• 제26권10호
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• pp.1167-1180
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• 2017

Numerical Weather Prediction (NWP) models such as the Weather Research and Forecasting (WRF) model are essential for forecasting one-day-ahead solar irradiance. In order to evaluate the performance of the WRF in forecasting solar irradiance over the Korean Peninsula, we compared WRF prediction data from 2008 to 2010 corresponding to weather observation data (OBS) from the Korean Meteorological Administration (KMA). The WRF model showed poor performance at polluted regions such as Seoul and Suwon where the relative Root Mean Square Error (rRMSE) is over 30%. Predictions by the WRF model alone had a large amount of potential error because of the lack of actual aerosol radiative feedbacks. For the purpose of reducing this error induced by atmospheric particles, i.e., aerosols, the WRF model was coupled with the Community Multiscale Air Quality (CMAQ) model. The coupled system makes it possible to estimate the radiative feedbacks of aerosols on the solar irradiance. As a result, the solar irradiance estimated by the coupled system showed a strong dependence on both the aerosol spatial distributions and the associated optical properties. In the NF (No Feedback) case, which refers to the WRF-only stimulated system without aerosol feedbacks, the GHI was overestimated by $50-200W\;m^{-2}$ compared with OBS derived values at each site. In the YF (Yes Feedback) case, in contrast, which refers to the WRF-CMAQ two-way coupled system, the rRMSE was significantly improved by 3.1-3.7% at Suwon and Seoul where the Particulate Matter (PM) concentrations, specifically, those related to the $PM_{10}$ size fraction, were over $100{\mu}g\;m^{-3}$. Thus, the coupled system showed promise for acquiring more accurate solar irradiance forecasts.

• 한국정보통신학회논문지
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• 제8권2호
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• pp.295-303
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• 2004

본 논문은 양방향 트래픽에서 비동기 전송모드 네트워크의 동적인 TCP 연결을 분석하고 트래픽 패턴을 프로토콜 상에서 네트워크 경로를 통해 개선됨을 연구한다. RTP(Round Trip Delay time)가 결정한 피드백루프의 시간 한계를 초과하는 정보의 형태로 조정하는 LTS 제어 모듈과 TCP를 연계시키는 방법에서 정보를 개연적인 특성을 갖고 여러 시간대에 걸처 분산하는 기존 윈도우를 기반으로 시연하기 때문이다. 이를 효과적으로 활용할 수 있는 방법으로 개선하며 TCP의 성능에서 자기 유사성 트래픽의 물리적 모델링에 기반한 시뮬레이션을 벤치마크 환경을 통해 수행한다. 본 논문은 양방향 네트워크에서 자기 유사성 트래픽 조건으로 스텍의 전송 프로토콜 변화의 영향을 파악 및 평가하는 방법론을 활용하고 과중한 조건에 자기유사성에 의해 경로 트래픽 혼잡제어 개선을 나타낸다.

• 한국전문물리치료학회지
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• 제23권3호
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• pp.48-56
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• 2016

Background: Recently, there has been an emphasis on the use of interventions with biofeedback information for the maintenance or correction of posture. Objects: This study assessed the change of trunk posture and trunk muscle activation when people exhibiting postural kyphosis performed visual display terminal work with or without a contact feedback device (CFD). Methods: Eighteen right-handed individuals were recruited. Thoracic angle and right thoracic erector spinae (TES) muscle amplitude were analyzed. There were two sessions in these experiments. The control session involved 16 minutes of typing without a CFD, and the CFD session involved 16 minutes of typing with a CFD. The visual analog scale score was analyzed with a paired t-test, and the kinematic and electromyography data were analyzed through two-way repeated analysis of variance. Results: The paired t-tests revealed that subjects had significantly less pain after the CFD sessions than after the control sessions (p<.05). Significant main effects by session and by time were observed in the thoracic kyphosis angle (p<.05). There was a significant session${\times}$time interaction for TES amplitude (p<.05), along with significant main effects by session and by time (p<.05). Conclusion: The CFD caused people with postural kyphosis to straighten and to activate their TES continuously, even though they were habituated to bend their bodies forward. Therefore, the CFD was a beneficial treatment tool.

• 문화기술의 융합
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• 제6권4호
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• pp.677-684
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• 2020

본 연구는 대구 Y대학교에 재학 중인 20대 대학생 15명을 무작위로 선발하였다. 실험 군은 총 3군으로 실험 전 각 실험 대상자들의 균형능력을 측정한 후, 시각되먹임을 이용한 균형운동으로 닌텐도 Wii(Nintendo -RVL-001(KOR)를 사용한 집단, 시각과 토구를 이용한 균형운동 집단, 시각을 차단하고 토구를 이용한 균형운동 집단 등 각 집단 5명을 훈련시킨 후 MFT와 EMG를 이용하여 측정하였다. MFT측정 결과 시각되먹임을 이용한 균형 훈련과 시각되먹임과 체성감각을 병행한 균형 훈련과의 상관관계에서는 유의한 결과를 나타내었고, 시각되먹임과 체성감각을 병행한 균형훈련과 체성감각만을 이용한 균형 훈련에서도 유의한 결과를 나타내었다(p<.05). EMG 측정 결과 시각되먹임을 이용한 훈련과 시각되먹임과 체성감각을 병행한 균형훈련과의 상관관계는 유의한 결과를 나타냈고(p<.05), 시각되먹임을 이용한 훈련과 체성감각만을 이용한 균형훈련, 그리고 체성감각만을 이용한 균형훈련과 시각되먹임을 병행한 체성감각훈련 사이에서는 유의한 결과가 나타나지 않았다. 본 실험에서는 시각되먹임만을 이용한 균형훈련보다 체성감각훈련을 병행하는 것이 더욱 효과적이었다. 따라서 균형능력이 감소된 환자들의 균형감각능력증진에 체성감각훈련이 좌우차이와 좌우빈도를 맞추는데 효과적이고 시각되먹임은 동적 균형 증진에 효과적이므로 이 두 훈련을 병행하는 것이 가장 효과적일 것이라고 생각된다.