• Archives of Pharmacal Research
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• 제21권1호
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• pp.35-40
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• 1998

Human cytochrome P450 4F2 shows high regioselectivity in hydroxylation of stearic acid and leukotriene $ B_4.$ As a first step of its regulation study, human cytochrome P450 4F2 genomic DNA was isolated from liver of a person who was administered clofibrate for 10 years. From Southern hybridization, restriction enzyme digestion and sequencing experiments, isolated genomic DNA fragment was found to contain around 32 Kb DNA and more than 20 Kb of $5^I$ end regulatory region. Sequences of the structural gene region revealed exon 1 and exon 2. Further regulation studies would elucidate the feedback mechanisms of the oxidative degradation of fatty acids, inflammatory response and the clearance of leukotriene B4 in the liver. Furthermore, regulation study of this gene could explain the species difference in responses to peroxisome proliferator and help in the safety evaluation of peroxisome proliferating chemicals to human being.

• 미생물학회지
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• 제29권3호
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• pp.160-166
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• 1991

The regulatory mechanism of tubercidin biosynthesis in Streptomyces tubercidicus was studied. In a wild type strain, addition of adenine and histidine into the medium decreased the tubercidin production by 60-65% and 40%, respectively. The effects of adenine and histidine were alleviated by the addition of inosine monophosphate and 5-aminoimidazole-4-carboxamide ribotide. The production of tubercidin in S. tubercidicus K115 strain ($ade^{-}$ ) was nearly shut off by histidine. In contrast with K115 strain, adenine inhibited the tubercidin biosynthesis in S. tubercidicus K412 strain ($his^{-}$. In S. tubercidicus F667 strain ($ade^{-}$ , $his^{-}$ ), tubercidin production was increased by adenine and histidine. From the effects of adenine and histidine on tubercidin biosynthesis in S. tubercidicus wild type and mutant strains, it became known that feedback control by adenine and histidine of biosynthetic pathwat for purine ribonucleotide and histidine are involved in the regulation of tubercidin biosynthesis.

• Animal cells and systems
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• 제16권1호
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• pp.1-10
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• 2012

Most living organisms synchronize their physiological and behavioral activities with the daily changes in the environment using intrinsic time-keeping systems called circadian clocks. In mammals, the key molecular features of the internal clock are transcription- and translational-based negative feedback loops, in which clock-specific transcription factors activate the periodic expression of their own repressors, thereby generating the circadian rhythms. CLOCK and BMAL1, the basic helix-loop-helix (bHLH)/PAS transcription factors, constitute the positive limb of the molecular clock oscillator. Recent investigations have shown that various levels of posttranslational regulation work in concert with CLOCK/BMAL1 in mediating circadian and cellular stimuli to control and reset the circadian rhythmicity. Here we review how the CLOCK and BMAL1 activities are regulated by intracellular distribution, posttranslational modification, and the recruitment of various epigenetic regulators in response to circadian and cellular signaling pathways.

• Journal of Power Electronics
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• 제15권1호
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• pp.39-53
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• 2015

This paper presents the regulation of the output voltage and inductor currents in a Single Ended Primary Inductor Converter (SEPIC), operating in the continuous conduction mode (CCM) using a sliding mode controller. Owing to the time varying nature of the SEPIC converter, designing a feedback controller is a challenging task. In order to improve the dynamic performance of the SEPIC, a Sliding Mode Controller (SMC) is developed. The developed SMC is designed by using a state space average model. The performance of the developed controller with the SEPIC converter is validated at different working conditions through Matlab simulations. It is also compared with the performance while using a PI controller. The results show that the designed controller gives very good output voltage regulation under different operating conditions such as a varying input voltage, changes in the load and component variations. A 48V, 46W experimental setup for has been developed in an analog platform to validate the performance of the proposed SMC.

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.56-64
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• 2019

Recently, as the environmental regulation for earth moving equipment has been tightened, advanced systems using electronic control have been introduced for energy savings. An IMV(Independent Metering Valve), which consists of four 2-way valves, is one of the electro-hydraulic control systems that provides more flexible controllability and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully realize an IMV, a two-stage bi-directional flow control valve which can regulate the large amount of flow in both directions, should be developed in advance. A simple design that allows proportional flow control to apply the pilot pressure from the current-controlled solenoid to the spring loaded flow control spool and thus valve displacement, is proportional to the solenoid current. However, this open-loop type valve is vulnerable to flow force which directly affects the valve displacement. Force feedback servo of which the position loop is closed by the feedback spring which interconnects the solenoid valve and flow control spool, could compensate for the flow force. In this study, linearity for the solenoid current input and robustness against load pressure disturbance is investigated by linear analysis of the static nonlinear equations for the IMV proportional flow control valve with feedback spring. Gains of the linear system confirm the performance improvement with the feedback spring design.

• 한국안전학회지
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• 제18권4호
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• pp.130-135
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• 2003

This study is planned to investigate the compliance of small sized enterprises of under 5 employees directed by Industrial Safety and Health Act. Occupational safety regulation can be required for employer and employee to comply because that all members of workplace should be involved to protect worker's health. When all members of workplace comply with safety regulation, effectiveness of regulation will be realized as expectation. The study subject is composed of three groups as 501 employers, 501 employees of small sized enterprises of under 5 employees and 107 safety inspectors sampled by stratified random sampling for comparison. Data for analysis is collected from each sample using interview with structured questionnaires. Compliance is measured by 5 point scale composed by 8 sub items such as general perception, understanding, clearness, necessity, relevancy, implementation, penalty, and general compliance of the regulation. Among sub items of employer's compliance, the level of perception of regulation, necessity of regulation, relevancy of penalty are differentiated among three groups. The level of all 8 items of employee's compliance also differentiated among three groups. These results show that strategies for ensuring the same level of compliance among three groups will be needed through education, training and evaluation of regulation and feedback.

• 식물조직배양학회지
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• 제24권5호
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• pp.273-277
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• 1997

Rhizoctonia solani 추출물(elicitor)을 Hyoscyamus muticus 모상근배양에 처리하였을 때 sesquiterpene cyclase (SC)가 유도됨과 동시에 sesquiterpene화합물이 합성되어 배양액속에 축적하는 것으로 나타났다. 24시간 배양기간 동안 배양액으로부터 sesquiterpene을 추출ㆍ분리하여 배양할 경우, 추출ㆍ분리하지 않은 모상근배양보다 거의 두배의 함량이 생성되었다. Cyclase monoclonal antibody을 이용하여 immunoblot을 시도한 결과, 추출한 모상근배양과 추출하지 많은 모상근배양에서의 SC 절대량은 동일한 것으로 나타났으며, 효소활성도 현저한 차이가 없는 것으로 측정되었다. 이러한 결과는 terpenoid pathway에서 sesquiterpene 생합성이 이용가능한 기질의 량에 의해 조절되는 것으로 사료되며, feedback 조절은 sesquiterpene cyclase 효소에 앞서 일어나는 것으로 추정된다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권1호
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• pp.10-15
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• 2003

This paper presents the digital computer performance evaluations of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover such as the wind turbine using the nodal admittance approach steady-state frequency domain analysis with the experimental results. The three-phase SEIG setup is implemented for small-scale rural renewable energy utilizations. The experimental performance results give a good agreement with those ones obtained from the digital computer simulation. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by a variable speed prime mover employing the static VAR compensator (SVC) circuit composed of the thyristor phase controlled reactor (TCR) and the thyristor switched capacitor(TSC) is designed and considered herein for the wind-turbine driven the power conditioner. To validate the effectiveness of the SVC-based voltage regulator of the terminal voltage of the three-phase SEIG, an inductive load parameter disturbances in stand-alone are applied and characterized in this paper. In the stand-alone power utilization system, the terminal voltage response and thyristor triggering angle response of the TCR are plotted graphically. The simulation and the experimental results prove the effectiveness and validity of the proposed SVC which is controlled by the Pl controller in terms of fast response and high performances of the three-phase SEIG driven directly by the rural renewable energy utilization like a variable-speed prime mover.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권1호
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• pp.1-9
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• 2003

This paper deals with the nodal admittance approach steady-state frequency domain analysis of the three-phase self-excited induction generator (SEIG) driven by the variable speed prime mover as the wind turbine. The steady-state performance analysis of this power conditioner designed for the renewable energy is based on the principle of equating the input mechanical power of the three-phase SEIG to the output mechanical power of the variable speed prime mover mentioned above. Us-ing the approximate frequency domain based equivalent circuit of the three-phase SEIG. The main features of the present algorithm of the steady-state performance analysis of the three-phase SEIG treated here are that the variable speed prime mover characteristics are included in the approximate equivalent circuit of the three-phase SEIG under the condition of the speed changes of the prime mover without complex computations processes. Furthermore, a feedback closed-loop voltage regulation of the three-phase SEIG as a power conditioner which is driven by variable speed prime movers such as the wind turbine(WT) employing the static VAR compensator(SVC) circuit composed of the thyristor phase controlled reactor(TCR) and the thyristor switched capacitor(TSC) controlled by the PI controller is designed and considered for wind-turbine driving power conditioner.

• 한국과학교육학회지
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• 제40권3호
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• pp.271-289
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• 2020

이 연구는 과정중심평가에서 나타나는 교사 피드백 유형의 사례를 제시하는 데 그 목적이 있다. 과정중심평가의 실행을 위하여 과정을 시각화한 협력적 모델링-논의 활동을 실시하였고, B고등학교 교사 4명과 학생 353명이 연구에 참여하였다. 자료의 분석은 논의 수업을 촬영한 영상, 협력적 모델링-논의 활동지 및 교사의 인터뷰 내용을 대상으로 실시하였다. 피드백의 유형화는 과학적 개념에 대한 피드백과 논의 과정에 대한 피드백의 범주를 바탕으로 하였으며, 각 피드백의 유형에 해당하는 사례는 교사 4명을 중심으로 추출하여 수업의 맥락과 함께 구체적으로 제시하였다. 연구 결과, 과학적 개념에 대한 피드백 중 개념 준거 제시형, 사고 촉진형 피드백이 학생의 자기 점검을 유도하였으며, 논의 과정에 대한 피드백 중 맥락 강조형 피드백, 과정 준거 제시형 피드백, 롤모델형 피드백, 그리고 인식 탐색형 피드백이 학생의 자기 점검을 유도하였다. 연구 결과를 토대로 과정중심 평가를 성공적으로 실시하기 위한 피드백의 특성과 과정중심평가에서의 교사의 역할을 도출하였다. 이 연구의 결과는 과정중심평가에서의 교사 피드백에 대한 이해를 기반으로 과정중심평가를 실천하기 위한 구체적인 지침을 제공해 줄 것으로 기대된다.