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구동한계를 고려한 ON/OFF 형식 구동시스템의 구동위치 제어기법 설계
박정우(Jungwoo Park),박익수(Iksoo Park),박동창(Dongchang Park),황기영(Kiyoung Hwang) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12
구동한계를 가지는 ON/OFF 구동장치를 이용한 PWM(Pulse Width Modulation) 제어기법 설계 과정을 기술하였다. 구동기 시험데이터를 이용하여 고려되는 구동기의 구동 동역학을 모렐링 하였으며, 단순화된 ON/OFF 구동 제어 성능을 개선하기 위해 모델링을 통해 선형화 된 수식 기반의 PWM 제어기법을 설계하였다. 최종적으로 제어 시뮬레이션을 통해 설계 방법을 검증하고 성능 개선 정도를 평가하였다. This paper represents a design procedure for a control method by an ON/OFF actuator via PWM control scheme with actuation limit. In this paper, based on experimental data, the actuation dynamics modeling is accomplished and a PWM control law is designed based on the linear actuation dynamics equations from the modeling process, which can improve the control performance by simple ON/OFF actuation. Finally the design method is verified and the performance improvement is evaluated through control simulations.
A firm's post-adoption behavior: loyalty or switching costs?
Park, Jun-Gi,Park, Kijun,Lee, Jungwoo Emerald Group Publishing Limited 2014 INDUSTRIAL MANAGEMENT & DATA SYSTEMS - Vol.114 No.2
<B>Purpose</B> - This study aims to investigate the influences of loyalty and switching costs toward a firm's overall post-adoption behavior in using information system. <B>Design/methodology/approach</B> - A research model is developed around two constructs found in the literature - loyalty and switching costs - that are most critical in firms' decisions on continued use of the same IS service providing company. It is empirically tested using a survey of IT decision makers in total 102 companies in South Korea. Partial least squares method is used to assess the relationships specified in research model. <B>Findings</B> - The findings suggest that both loyalty and switching costs have positive influences on the continuous intention to use and the inattentiveness of alternatives. <B>Research limitations/implications</B> - Findings are based on a single point cross-sectional survey. To further investigate the continuance of specific IT service firms, triangulation will be necessary with longitudinal and qualitative data concerning the process of decision-making, including political and contractual situation. <B>Originality/value</B> - The study fills the research gap in studying post-adoption behavior at the firm level by empirically testing the duality of loyalty and switching costs.
Park, Jungwoo,Yoo, Ji Wang,Seo, Hee Won,Lee, Youngkwan,Suhr, Jonghwan,Moon, Hyungpil,Koo, Ja Choon,Choi, Hyouk Ryeol,Hunt, Robert,Kim, Kwang Jin,Kim, Soo Hyun,Nam, Jae-Do Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.3
<P>As a new class of thermally activated actuators based on polymeric fibers, we investigated polyethylene terephthalate (PET) yarns for the development of a twisted-coiled polymer fiber actuator (TCA). The PET yarn TCA exhibited the maximum linear actuation up to 8.9% by external heating at above the glass transition temperature, 160 °C–180 °C. The payload of the actuator was successfully correlated with the preload and training-load conditions by an empirical equation. Furthermore, the PET-based TCA was electrically driven by Joule heating after the PET surface was metallization with silver. For the fast and precise control of PET yarn TCA, electroless silver plating was conducted to form electrical conductive layers on the PET fiber surface. The silver plated PET-based TCA was tested by Joule heating and the tensile actuation was increased up to 12.1% (6 V) due to the enhanced surface hardness and slippage of PET fibers. Overall, silver plating of the polymeric yarn provided a fast actuation speed and enhanced actuation performance of the TCA actuator by Joule heating, providing a great potential for being used in artificial muscle for biomimetic machines including robots, industrial actuators and powered exoskeletons.</P>
Optimal Spot-Checking Ratio for Probabilistic Attacks in Remote Data Checking
PARK, Younsoo,CHOI, Jungwoo,KWON, Young-Bin,PARK, Jaehwa,PARK, Ho-Hyun 'Institute of Electronics, Information and Communi 2017 IEICE transactions on information and systems Vol.100e.d No.8
<P>Remote data checking (RDC) is a scheme that allows clients to efficiently check the integrity of data stored at an untrusted server using spot-checking. Efforts have been consistently devoted toward improving the efficiency of such RDC schemes because they involve some overhead. In this letter, it is assumed that a probabilistic attack model is adopted, in which an adversary corrupts exposed blocks in the network with a certain probability. An optimal spot-checking ratio that simultaneously guarantees the robustness of the scheme and minimizes the overhead is obtained.</P>
A Way-Filtering-Based Dynamic Logical–Associative Cache Architecture for Low-Energy Consumption
Park, Jungwoo,Lee, Jongmin,Kim, Soontae IEEE 2017 IEEE transactions on very large scale integration Vol.25 No.3
<P>Last-level caches (LLCs) help improve performance but suffer from energy overhead because of their large sizes. An effective solution to this problem is to selectively power down several cache ways, which, however, reduces cache associativity and performance and thus limits its effectiveness in reducing energy consumption. To overcome this limitation, we propose a new cache architecture that can logically increase cache associativity of way-powered-down LLCs. Our proposed scheme is designed to be dynamic in activating an appropriate number of cache ways in order to eliminate the need for static profiling to determine an energy-optimized cache configuration. The experimental results show that our proposed dynamic scheme reduces the energy consumption of LLCs by 34% and 40% on single-and dual-core systems, respectively, compared with the best performing conventional static cache configuration. The overall system energy consumption including CPU, L2 cache, and DRAM is reduced by 9.2% on quad-core systems.</P>
Optical Properties and Field Emission of ZnO Nanorods Grown on p-Type Porous Si
Park, Taehee,Park, Eunkyung,Ahn, Juwon,Lee, Jungwoo,Lee, Jongtaek,Lee, Sang-Hwa,Kim, Jae-Yong,Yi, Whikun Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.6
N-type ZnO nanorods were grown on p-type porous silicon using a chemical bath deposition (CBD) method (p-n diode). The structure and geometry of the device were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) while the optoelectronic properties were investigated by UV/Vis absorption spectrometry as well as photoluminescence and electroluminescence measurements. The field emission (FE) properties of the device were also measured and its turn-on field and current at 6 $V/{\mu}m$ were determined. In principle, the growth of ZnO nanorods on porous siicon for optoelectronic applications is possible.
Properties and applications of starch modifying enzymes for use in the baking industry
Park, Sung Hoon,Na, Yerim,Kim, Jungwoo,Kang, Shin Dal,Park, Kwan-Hwa 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.2
Enzyme technology has many potential applications in the baking industry because carbohydrate-active enzymes specifically react with carbohydrate components, such as starch, in complex food systems. Amylolytic enzymes are added to starch-based foods, such as baking products, to retain moisture more efficiently and to increase softness, freshness, and shelf life. The major reactions used to modify the structure of food starch include: (1) hydrolysis of ${\alpha}-1$, 4 or ${\alpha}-1$, 6 glycosidic linkages, (2) disproportionation by the transfer of glucan moieties, and (3) branching by formation of ${\alpha}-1$, 6 glycosidic linkage. The catalytic reaction of a single enzyme or a mixture of more than two enzymes has been applied, generating novel starches, with chemical changes in the starch structure, in which the changes of molecular mass, branch chain length distribution, and the ratio of amylose to amylopectin may occur. These developments of enzyme technology highlight the potential to create various structured-starches for the food and baking industry.