• Journal of Korea Game Society
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• v.13 no.2
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• pp.5-16
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• 2013

The purpose of this study is how to occur the temporality in Digital Gameplay. There is two types of time in Gameplay. One is Irreversibility time that goes passed through a game world like a chronology order. Another is Reversibility time that returns and renews the time. The time's duality is caused by player's intervene and experience. And the polychronic temporality in gameplay makes the rhythm as replay and eternal cyclic time.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.91-97
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• 1997

In the course of magnetic study on several perovskite-type oxides, A2Fe(Ⅲ)BO6 (A = Ca, Sr, Ba and B = Sb, Bi), we have observed a strong irreversibility in their dc-magnetizations. When the structural data and the Mossbauer spectra are considered, such an irreversibility is to be associated with some competitions between the nearest-neighbors (nn) and the next-nearest-neighbors (nnn) in their magnetic sublattices. Particularly, the Mossbauer spectra indicate that Sr2FeBiO6 of cubic perovskite-structure is apparently well ordered crystalline compound. Nontheless this antiferromagnet shows a magnetic property which resembles that of a spin-glass. The strong history dependence is observed below 91 K and the irreversible magnetic behavior is also observed from the measurement of hysteresis loops at 10 K after zero-field-cooled (zfc) and field-cooled (fc) processes. Considering the nn and the nnn superexchanges of almost same order in ordered perovskite, it is proposed that there exists a competition and cancellation of antiferromagnetic and ferromagnetic superexchange between the nearest-neighbors and the next-nearest-neighbors, thus introducing a certain degree of frustration.

• Proceedings of the Microbiological Society of Korea Conference
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• 1998.04a
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• pp.41.1-41.1
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• 1998

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.285-296
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• 2005

In order to reduce the compression power and to use the overall energy contained in LNG effectively, a combined cycle is devised and simulated. The combined cycle is composed of two cycles; one is an open cycle of liquid/solid carbon dioxide production cycle utilizing LNG cold energy in $CO_2$ condenser and the other is a closed cycle gas turbine which supplies power to the $CO_2$ cycle, utilizes LNG cold energy for lowering the compressor inlet temperature, and uses the heating value of LNG at the burner. The power consumed for the $CO_2$ cycle is investigated in terms of a production ratio of solid $CO_2$. The present study shows that much reduction in both $CO_2$ compression power (only $35\%$ of power used in conventional dry ice production cycle) and $CO_2$ condenser pressure could be achieved by utilizing LNG cold energy and that high cycle efficiency ($55.3\%$ at maximum power condition) in the gas turbine could be accomplished with the adoption of compressor inlet cooling and regenerator. Exergy analysis shows that irreversibility in the combined cycle increases linearly as a production ratio of solid $CO_2$ increases and most of the irreversibility occurs in the condenser and the heat exchanger for compressor inlet cooling. Hence, incoming LNG cold energy to the above components should be used more effectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.484-496
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• 1996

This paper presents an anlaysis on the thermodynamic performance of ice storage system. The primary interest in this work is the exergetic efficiency of the system. The ice storage system considered here is the capsule type system with the waste plastic bottle being used as a capsule. To examine the characteristics of irreversibility production and exergetic efficiency in detail the ice storage system to be analyzed has been separated from the refrigerator in this analysis. The analysis is based on the lumped model with 3 uniform temperatures. The results indicate that 3 dimensionless parameters can describe the exergetic efficiency of the system, from which the characteristics of irreversibilities and the ranges of these parameters to ensure the reasonable performance of the system can be found. Experiments also have been performed to demonstrate the feasibility of such a system. This analysis only shows the performance of ice storage side, with the refrigeration side excluded. However, the results can be interpreted as a total performance if the refrigerator coupled with the ice storage system operatres reversibly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.362-362
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• 2009

$MgB_2$ bulk samples were sintered at different ambient. In this work, high purity Ar gas was added with oxygen and hydrogen gas, which can be regarded as impurity in a sense, as a possible dopant in the $MgB_2$. It was found that oxygen in the sintering ambient leads to a decrease in the critical current density $J_c$ at self field and lower fields. However, we can obtained higher $J_c$ at higher fields. It was also noted that $MgB_2$ samples sintered with 5% hydrogen in Ar revealed the increased $J_c$ at all fields compared to those processed in pure Ar ambient. From the XRD and FESEM analysis, the impurity gas in Ar can refine the $MgB_2$ grain size and result in increased grain. boundary, which can act as a strong flux pinning sites in $MgB_2$ samples. Also discussed are the effects of sintering ambient on irreversibility field, $H_{irr}$ and the upper critical field, $H_{C2}$.

• Environmental and Resource Economics Review
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• v.20 no.3
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• pp.459-487
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• 2011

A/R CDM project has properties such as irreversibility and uncertainty that Real Option Analysis can be applied to its modelling. This study tries to model A/R CDM using Real Option under CER price uncertainty, and conducts empirical test with the Posco A/R CDM Project case. For precise comparison and decision-making, l-CER's expected present value is calculated from the Spot CER price. As a result, the critical value of the project is lower than the expected l-CER price, which means that the decision to invest made by the project owner is profitable. We can also find out that the level and the range of the discount rate, where is applied to, affect the result; the critical value of the project and the decision-making.

• Progress in Superconductivity
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• v.9 no.2
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• pp.183-187
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• 2008

We have studied superconducting properties of $Mg_{1-x}Al_xB_2$ single crystals from reversible magnetization measurements. It was found that the upper critical fields $H_{c2}$ were decreased for both H // c and H // ab as Al is substituted for Mg. As a result, the large anisotropy of $H_{c2}$ observed in pure $MgB_2$, which is considered as one of the characteristics of two-gap superconductor, was decreased with Al doping. On the other hand, the irreversibility fields $H_{irr}$ were increased for x = 0.1 and were significantly decreased for x = 0.2. In contrary to the anisotropy of $H_{c2}$, the anisotropy of $H_{irr}$ was increased as Al concentration increases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.550-560
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• 2000

In order to minimize compression power and analyze the cause of exergy loss for a dry ice production cycle with 3-stage compression, the variation of compression power was investigated and the exergy analysis was peformed for the cycle. In this cycle, $CO_2$, is used both as a refrigerant and as a raw material for dry ice. The behavior of compression power and irreversibility in the cycle were examined as a function of intermediate pressure. From this result, the conditions for the minimum compression power were obtained in terms of the first stage or the third stage pressure. In addition, the irreversibilities for the cycle were investigated with respect to the efficiency of compressor. Result shows that the optimum pressure is not consistent with the conventional pressure obtained from the equal-pressure-ratio assumption. This is mainly due to the change in mass flow rate of the intermediate stage compressor by the flash gas evaporation from the flash drums. Most important is that the present exergy analysis enabled us to find bad performance components for the cycle and informed us of methods to improve the cycle performance.

• Toxicological Research
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• v.30 no.3
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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.