• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1719-1721
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• 2012

We have investigated the $H_2$ adsorption structures and binding energies of the metal (M)-doped (M = Li, Na, K, Mg, and Al) silicon complexes, $M-Si_{19}H_{11}$ and $M-Si_{24}H_{12}$, using density functional calculations. Alkali metals are preferred as doping elements because the Mg-Si and Al-$H_2$ interactions are weak. The maximum numbers of $H_2$ molecules that can be adsorbed are four and five for M=Li and K, respectively. We propose that the K-decorated silicon material might be an effective hydrogen storage material with high hydrogen capacity and high reversibility.

• Transactions on Electrical and Electronic Materials
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• 제8권4호
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• pp.157-160
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• 2007

Lithium-sulphur batteries were fabricated in a dry room, and their electrochemical properties were analyzed by scanning electron microscopy (SEM), cyclic voltammetry (CV), and charge-discharge tests. SEM results showed that sulphur and nanocarbon powders were mixed homogeneously, and sulphur powders were enwrapped by a large amount of carbon powders. The charge-discharge test results demonstrated that the lithium-sulphur battery displayed excellent reversibility and cycling performance, which supplied a discharge capacity of $788.1mAh\;g^{-1}$ at the first cycle and $796.4mAh\;g^{-1}$ after 71 cycles at room temperature, respectively.

• 한국게임학회 논문지
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• 제13권2호
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• pp.5-16
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• 2013

본고는 디지털 게임을 플레이할 때 발생하는 시간의 여러 층위와 그 구조적 특성을 통해 모순적으로 보이는 게임 플레이의 시간성이 서로 결합하는 양상과 그 결과로 만들어내는 리듬을 규명하는 것을 목적으로 한다. 디지털 게임 플레이는 첫째, 연대기적으로 흐르는 불가역적 시간의 지배 속에서 언제든 시간을 정지시키고 변화시킬 수 있는 가역성을 동시에 추구한다. 둘째, 이런 이중적인 시간 체계가 공존할 수 있는 이유는 게임의 시간에 플레이어가 개입하기 때문이다. 마지막으로 이렇게 복잡해 보이는 다층적 시간 체계는 이미 진행되었던 게임 플레이를 다시 한 번 반복하는 식의 리플레이라는 특수한 게임 플레이 활동을 통해 리듬을 만들어낸다.

• 대한수학회보
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• 제56권5호
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• pp.1257-1272
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• 2019

This article concerns the structure of idempotents in reversible and pseudo-reversible rings in relation with various sorts of ring extensions. It is known that a ring R is reversible if and only if $ab{\in}I(R)$ for $a,b{\in}R$ implies ab = ba; and a ring R shall be said to be pseudoreversible if $0{\neq}ab{\in}I(R)$ for $a,b{\in}R$ implies ab = ba, where I(R) is the set of all idempotents in R. Pseudo-reversible is seated between reversible and quasi-reversible. It is proved that the reversibility, pseudoreversibility, and quasi-reversibility are equivalent in Dorroh extensions and direct products. Dorroh extensions are also used to construct several sorts of rings which are necessary in the process.

• 대한수학회보
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• 제48권3호
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• pp.611-616
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• 2011

The reflexiveness and reversibility were introduced by Mason and Cohn respectively. The structures of minimal reversible rings and minimal reflexive rings are completely determined. The term minimal means having smallest cardinality.

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 2009년도 제17차 학술대회
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• pp.223-223
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• 2009

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 2009년도 제17차 학술대회
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• pp.76-76
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• 2009

• 폴리머
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• 제39권3호
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• pp.359-364
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• 2015

A self-oscillating interpenetrating polymer network (IPN) poly(acrylic acid)/poly(ethylene glycol) (PAA/PEG) hydrogel was prepared by using radical polymerization with a two-step method. The IPN hydrogel was characterized by FTIR spectroscopy and morphological analysis. The results indicated that the chains of PEG and PAA twined to form porous structure which is beneficial to water molecules entering inside of the hydrogel. In addition, the pH-responsive behavior, salt sensitivity, swelling/de-swelling oscillatory behaviors and self-oscillation in a closed pH oscillator were also studied. The results showed that the prepared hydrogel exhibited pH-sensitivity, good swelling/de-swelling reversibility and excellent salt sensitivity. The self-oscillating behavior of swelling/de-swelling for the prepared hydrogel was caused by pH alteration coupled with the external media. This study may create a new possibility as biomaterial including new self-walking actuators and other related devices.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제24권3호
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• pp.709-730
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• 2010

본 연구에서 함수를 어려워하는 원인이 함수의 가역성에 기인하는지 살펴보고자 가역적 사고가 요구되는 무리함수의 개념과 가역성을 분석하였다. 함수와 관련하여 저학년에서 형성된 개념이 불균형 상태로 고착화되어 있다. 하위권 학생들의 시각화, 기호 이해, 특히 가역적 사고 능력이 부족하여 오류 현상을 보이고 있다. 저학년부터 생활 주변의 가역적인 사고를 요하는 내용을 다루지만, 학생들은 가역성이 내포된 함수 내용을 어려운 대상으로만 간주하고 인지 구조의 조절 과정을 의도적으로 회피하거나, 인출하여도 연결성이 부족하고 부정확한 개념으로 응답하고, 특히 가역성이 내포된 문제에 대하여 반응율과 정답율이 낮으며 다양한 오류 현상이 나타났다.

• Toxicological Research
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• 제30권3호
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• pp.179-184
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• 2014

Xenobiotics causing a variety of toxicity in biological systems could be classified as two types, inorganic and organic chemicals. It is estimated that the organic xenobiotics are responsible for approximately 80~90% of chemical-induced toxicity in human population. In the class for toxicology, we have encountered some difficulties in explaining the mechanisms of toxicity caused especially by organic chemicals. Here, a simple flowchart was introduced for explaining the mechanism of toxicity caused by organic xenobiotics, as the central dogma of molecular biology. This flowchart, referred to as a central dogma, was described based on a view of various aspects as follows: direct-acting chemicals vs. indirect-acting chemicals, cytochrome P450-dependent vs. cytochrome P450-independent biotransformation, reactive intermediates, reactivation, toxicokinetics vs. toxicodynamics, and reversibility vs. irreversibility. Thus, the primary objective of this flowchart is to help better understanding of the organic xenobiotics-induced toxic mechanisms, providing a major pathway for toxicity occurring in biological systems.