• 한국유체기계학회 논문집
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• 제7권1호
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• pp.30-35
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• 2004

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. HANARO flow simulation facility is being developed for the endurance test of reactivity control units for extended life time and the verification of structural integrity of those experimental equipments prior to loading in the HANARO. This facility is composed of three major parts; a half-core structure assembly, a flow circulation system and a support system. The flow circulation system is composed of a circulation pump, a core flow piping, a core bypass flow piping and instruments. The system is to be filled with de-mineralized water and the flow should be met the design requirements to simulate a similar flow characteristics in the core channel of the half-core structure assembly to the HANARO. This paper, therefore, presents an analytical analysis to study the flow behavior of the system. Computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with the standard $k-{\epsilon}$ turbulence model and for the verification of the structural piping integrity through the finite element method. According to the analysis results, it could be said that the design requirements and the structural piping integrity of the flow circulation system are satisfied.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.182-188
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• 2017

An arc eliminator allows a surge current bypass rapidly into the earth to facilitate the circuit breaking process and increase the stability of the load circuit. Thomson coil actuator (TCA) is a type of actuator that can function as an arc eliminator. The TCA has a simple structure and significantly rapid speed compared to the other types of actuators. In this paper, significant variables, which have a dominant effect on the performance of the TCA, are investigated in detail. Using these variables and an optimization algorithm, an optimal design strategy for the TCA is proposed in this research. The efficacy of the proposed optimal design strategy and the feasibility of the application of the designed TCA for a high power circuit breaker as the arc eliminators are validated through the experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.206-208
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• 2009

In this paper, a systematical controller design method for a twostage grid-connected photovoltaic power conditioning system is proposed. For a pre-stage boost converter to achieve the stable operation in the entire region of solar array, the digital resistive current mode controller is used. This algorithm is very simple to implement with a digital controller and there is no power stage parameter dependency in the controller design. For a post-stage single-phase full-bridge inverter, a PI controller with a feedforward compensation for the inner current control is employed. Furthermore, in case that the operating point of the solar array under varying environmental conditions is higher than the required voltage for the inverter current control, the bypass mode for the boost converter is possible for the more efficient operation. The proposed control scheme is validated through the experiment of the prototype two-stage power conditioning system hardware with a 200W solar array.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.976-978
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• 1998

In this paper, we designed basic concept and structure of bypassing device which promoted the activity of low voltage line-fuse, when it perceived the too small short-fault current to activate line-fuse which located at the between secondary of pole transformer and home immediately. And we study displacement of bypass contact and electromagnetic force caused by the short-fault current by the basic experiment to understand the basic characteristic of bypassing movements.

• 열처리공학회지
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• 제9권2호
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• pp.91-102
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• 1996

Microstructural control to produce multiphase structure has received much attention to improve the high temperature strength as well as low temperature ductility of intermetallics. Transmission electron microscopic investigation has been carried out concerning the effect of Cr-precipitation on the mechanical properties of B2-ordered NiAl containing 4 to 8 mol% of Cr. By aging at temperatures around 973 K after solution annealing, fine spherical precipitates took place homogeneously in the NiAl matrix and the alloys hardened appreciably. Selected area electron diffraction (SAED) patterns have not revealed any additional extra-spots during aging, because the Cr-particles show cube-cube orientation relationship and keep a perfect coherency with the ordered matrix lattice. Dislocations were confirmed to bypass the particles during deformation. Although the dispersion of Cr-particles increased the yield strength of NiAl at intermediate temperature, the strength decreased appreciably at higher temperatures.

• Molecules and Cells
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• 제26권3호
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• pp.308-313
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• 2008

In animals, microRNAs (miRNAs) and small interfering RNAs (siRNAs) repress expression of protein coding genes by assembling distinct RNA-induced silencing complexes (RISCs). It has previously been shown that passenger-strand cleavage is the predominant mechanism when siRNA duplexes are loaded into Argonaute2 (Ago2)-containing RISC, while an unwinding bypass mechanism is favored for miRNA duplexes with mismatches. Here I present experimental data indicating that some mammalian miRNAs are assembled into Ago2-containing RISC by cleaving their corresponding miRNA star strands. This phenomenon may depend on the secondary structure near the scissile phosphate of the miRNA duplex. In addition, I show that ATP is not required for star-strand cleavage in this process. Taken together, the data here provide insight into the miRNA-loading mechanisms in mammals.

• ETRI Journal
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• 제43권3호
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• pp.549-560
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• 2021

Cyberattacks are often difficult to identify with traditional signature-based detection, because attackers continually find ways to bypass the detection methods. Therefore, researchers have introduced artificial intelligence (AI) technology for cybersecurity analysis to detect malicious PowerShell scripts. In this paper, we propose a feature optimization technique for AI-based approaches to enhance the accuracy of malicious PowerShell script detection. We statically analyze the PowerShell script and preprocess it with a method based on the tokens and abstract syntax tree (AST) for feature selection. Here, tokens and AST represent the vocabulary and structure of the PowerShell script, respectively. Performance evaluations with optimized features yield detection rates of 98% in both machine learning (ML) and deep learning (DL) experiments. Among them, the ML model with the 3-gram of selected five tokens and the DL model with experiments based on the AST 3-gram deliver the best performance.

• 미국학
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• 제43권2호
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• pp.83-110
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• 2020

This paper examines the meaning and significance of the rebirths narrated in Sylvia Plath's "Lady Lazarus." While the previous readings of the poem have regarded the speaker's rebirth as a single event, this paper aims to understand its plurality and the underlying problem of language and sound by listening to the poet's own reading of the poem. I argue first that the sound structure of the poem can be characterized by the poet's unique employment of vowel sounds. Drawing upon Plath's another poem entitled "Morning Song" and Julia Kristeva's concept of the chora, I contend that the poet's vowels signal her desire for regression to the pre-Oedipal space where sound and body are in direct contact without the interference of language. It is my conclusion that the rebirths in "Lady Lazarus" dramatize the poet's ongoing struggle to bypass the symbolic language in order to make her body heard.

• 한국정보통신학회논문지
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• 제23권6호
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• pp.719-725
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• 2019

본 연구에서는 2.4-GHz CMOS 전력 증폭기의 저 출력 전력 영역에서의 전력 변환 효율을 개선시키기 위한 이중모드 증폭기 구조를 제안하였다. 이를 위하여 출력 정합 회로 및 발룬의 역할을 하는 출력부 변압기의 1차 측을 두 개로 나누고, 그 중 하나는 전력 증폭단의 출력부와, 나머지 하나는 구동 증폭단의 출력부와 연결 되도록 구성하였다. 이를 통하여, 전력 증폭기가 고 출력 전력 영역에서 동작 할 경우, 일반적인 전력 증폭기 동작과 동일하게 동작 하며, 반대로 전력 증폭기가 저출력 전력 영역에서 동작 할 경우, 전력 증폭단은 작동을 하지 않으며, 구동 증폭단의 출력이 전력 증폭기의 최종 출력부로 전달 되도록 구성하였다. 이 경우, 저출력 전력 영역에서는 전력 증폭단에서의 dc 전력소모가 원천적으로 차단되기 때문에 저출력 전력 영역에서의 전력 변환 효율을 개선시킬 수 있다. 제안하는 구조는 180-nm RFCMOS 공정을 통해 설계된 2.4-GHz 전력 증폭기의 측정을 통하여 그 효용성을 검증하였다.

• 대한전자공학회논문지SD
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• 제42권5호
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• pp.15-22
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• 2005

본 논문에서는 생명체의 구조를 모방하여, 디지털시스템에서 자가검출과 자가치유가 가능한 구조를 제안한다. 자가치유시스템은 인공 셀의 2차 배열과 여분의 인공 셀로 구성된다. 인공 셀은 멀티플렉서를 기본으로 한 로직블록(logic block)과 로직블록을 제어하기 위한 게놈블록(genome block)으로 구성된다. 인공 셀은 자가검출이 가능하도록 DCVSL (differential cascode voltage switch logic)구조로 설계된다. 만약 인공 셀에서 고장이 발생하면, 자가 검출되고 고장 난 인공 셀이 속한 열은 bypass기능만을 가지고 치유를 위해, 여분 셀과 이웃 셀을 이용하여 시스템을 재구성한다. 하이닉스 $0.35{\mu}m$공정을 이용해 $1.14{\times}0.99mm^2$의 코어면적을 가지는 2비트 업다운카운터를 제작하였고 회로시뮬레이션과 칩 테스트를 통해 검증하였다.