• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.270-274
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• 2012

The nucleophilic substitution reactions of 1,2-phenylene phosphorochloridate (1c) with X-pyridines are investigated kinetically in acetonitrile at $-25.0^{\circ}C$. The free energy correlations for substituent X variations in the nucleophiles exhibit biphasic concave upwards with a break point at X = 3-Ph. The pyridinolysis rate of 1c with a cyclic five-membered ring is $2.70{\times}10^5$ times faster than its acyclic counterpart (1a: phenyl ethyl chlorophosphate) because of great positive value of the entropy of activation of 1c (${\Delta}S^{\neq}$ = +26 eu) compared to negative value of 1a (${\Delta}S^{\neq}$= -24 eu) over considerably unfavorable enthalpy of activation of 1c (${\Delta}H^{\neq}=20.5kcal\;mol^{-1}$) compared to 1a (${\Delta}H^{\neq}=12.7kcal\;mol^{-1}$). Great enthalpy and positive entropy of activation are ascribed to sterically congested transition state (TS) and solvent structure breaking in the TS. A concerted mechanism involving a change of nucleophilic attacking direction from a frontside attack with the strongly basic pyridines to a backside attack with the weakly basic pyridines is proposed on the basis of greater selectivity parameters (${\rho}_X$ = -1.99 and ${\beta}_X$ = 0.41) with the strongly basic pyridines compared to those (${\rho}_X$ = -0.42 and ${\beta}_X$ = 0.07) with the weakly basic pyridines.

• Membrane Journal
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• v.21 no.4
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• pp.307-320
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• 2011

Polymeric gas separation membrane is the fastest growing field in membrane separation process. Polymeric gas separation membrane process is competitive compare to cryogenic process and pressure swing adsorption process. Aromatic polymer materials such as polysulfones, polypheneylene oxides, polycarbonates and polyimides have been used for gas separation. Recently, glassy polymer likes polyimide in aromatic polymers has been developed for achievement of high selectivity and permeability coefficients. The accurate understanding on a type and structure of polymer material is very important, because the factor that polymer material affect gas separation property. In the study, trend and the development direction on synthesis and permeation properties of polyimide is confirmed.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.99-110
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• 2013

Redox flow batteries are attractive energy-storage devices for renewable energy and peak-power energy control. Even though some prototypes are available already, many new materials are under development for new battery systems. In this reports, redox pairs and theirs properties are explained, by which one can understand issues with redox pairs, such as contaminations, cross-over, ionic selectivity, and solubility. Batteries that have the same redox pairs in both electrode compartments can be operated longer than those with different redox pairs due to the prevention form the cross-contamination. There are undivided redox flow batteries that have no membrane, which is another direction improving cycle life of the batteries.

• 한국노년학
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• v.37 no.1
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• pp.201-219
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• 2017

This study was performed to test the socioemotional selectivity theory (SST) with Korean adults. According to SST, perceiving their life as limited, people are motivated to enhance their mood by regulating their mood in such a way to maximize the positive emotions and weaken the negative ones. Being founded on the dialectical constructs which assume the positive and negative sides of emotional experience coexist, Korean adults were supposed to be less motivated to maximize positive emotions and weaken negative emotions. Thus the elderly koreans might regulate emotions not in the direction of maximizing the positive emotions and weakening the negative ones, but in the direction of not being highly aroused. 166 youth, middle-aged, and elderly were asked to rate the frequencies of 31 positive and negative emotions they had experienced during the last month. In addition, they were asked to judge whether they weaken / adapt / maximize their emotions after experiencing positive and negative events. The elderly experienced less positive emotions as well as negative emotions than youth. Youth experienced emotions of high arousal more often than those of low arousal, but the elderly experienced emotions of high arousal less often. The responses of weakening their negative emotions and their positive emotions were largest in the elderly group. On the other hand, the response of maximizing their positive emotions were largest in the youth group. These results show that the elderly maintains emotional stability by weakening both positive and negative emotions of high arousal.

• Journal of Software Assessment and Valuation
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• v.16 no.1
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• pp.55-63
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• 2020

Lasers for optical broadband communication systems should have excellent frequency selectivity and modal stability. DFB lasers have low lasing frequency shift during high speed current modulation. In this paper, when a refractive index grating and a gain grating are simultaneously present in a DFB laser having a wavelength of 1.55 ㎛, the dielectric film is coated so that reflection does not occur on the right mirror surface, so that ρ_r=0. For the first mode, which requires a minimum gain at the threshold, the beam distribution of the oscillation mode in the longitudinal direction and the radiated power ratio P_l/P_r were analyzed and compared for the cases of the phase of ρ_l=π and π/2. If the phase of ρ_l=π, in order to obtain a low threshold current and high frequency stability, κL should be greater than 8. In the case of the phase of ρ_l=π/2, for low threshold current, κL is necessary to be 1.0, where the oscillation frequency coincides with the lattice frequency. DFB lasers with an anti-reflection coated mirror have excellent mode selectivity than 1.55um DFB lasers with two mirror facets

• Journal of Families and Better Life
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• v.6 no.1
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• pp.167-187
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• 1988

The purpose of this study is to explore whether wives communicate differently over the family life cycle(FLC), and whether their communication contents and frequencies are differently over the FLC. Marital communication scales are composed of six subfactors such as The selectivity of channel (SC), Channel direction (CD), communication style(CS), Comprehension of nonverbal communication (CNC), Communication contents and frequencies(CCF) and Olson's marital communication (LCQ). The number of the subjects are 582, who are living in Pusan in 1987 and they divided into six stages family life cycle; The newly married (FLC 1). The family with preschoolers(FLC 2), The family with schoolages (FLC3), The family with teenages(FLC4)， The family with launching children(FLC 5) and The postparenthood (FLC 6). This study is surveyed by Frequencies and Mean score from six subfactors and tested by chi-square test and ANOVA. the results are as follows; 1) There are a few significant differences in CS and CNC by FLC. The wives from FLC 1 and FLC 2 use the most open communication style and them form FLC5 use the most closed style. There are revealed that comprehension of nonverbal communication is the highest of FLC2, but on FLC 1 it is the lowest. 2) There are significant difference in CCF. Children, Wive's life, Husband's life, Affection and sex and Empathy show significant differences over the over the FLC. Regardless of FLC, there are conclueded that Children, Wive's and husband's life and economy management are the most frequence communicative contents. These results suggest that there needs to be further investigation on Olson's marital communication scale for comparing another country with ours and on the training and programs for couple's skillful communication ability.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.174-174
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• 2014

Memristor devices are one of the most promising candidate approaches to next-generation memory technologies. Memristive switching phenomena usually rely on repeated electrical resistive switching between non-volatile resistance states in an active material under the application of an electrical stimulus, such as a voltage or current. Recent reports have explored the use of variety of external operating parameters, such as the modulation of an applied magnetic field, temperature, or illumination conditions to activate changes in the memristive switching behaviors. Among these possible choices of signal controlling factors of memristor, photon is particularly attractive because photonic signals are not only easier to reach directly over long distances than electrical signal, but they also efficiently manage the interactions between logic devices without any signal interference. Furthermore, due to the inherent wave characteristics of photons, the facile manipulation of the light ray enables incident light angle controlled memristive switching. So that, in the tautological sense, device orienting position with regard to a photon source determines the occurrence of memristive switching as well. To demonstrate this position controlled memory device functionality, we have fabricated a metal-semiconductor-metal memristive switching nanodevice using ZnO nanorods. Superhydrophobicity employed in this memristor gives rise to illumination direction selectivity as an extra controlling parameter which is important feature in emerging. When light irradiates from a point source in water to the surface treated device, refraction of light ray takes place at the water/air interface because of the optical density differences in two media (water/air). When incident light travels through a higher refractive index medium (water; n=1.33) to lower one (air; n=1), a total reflection occurs for incidence angles over the critical value. Thus, when we watch the submerged NW arrays at the view angles over the critical angle, a mirror-like surface is observed due to the presence of air pocket layer. From this processes, the reversible switching characteristics were verified by modulating the light incident angle between the resistor and memristor.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.117-123
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• 1992

$Pt-SnO_{2-x}$ thin film sensing devices has been fabricated by thermal oxidation of stacked Pt-Sn thin film on the heater. The thickness of Sn thin film deposited by thermal evaporation was $4000{\AA}$ and the thickness of Pt deposited by D. C. sputtering on Sn thin film was $14{\sim}71{\AA}$ range. The XRD analysis show that the $Pt-SnO_{2-x}$ thin films are formed by grains with a diameter of about $200{\AA}$ randomly connected and the crystalline phase of the thin films are preferentally oriented in the (110) direction. $Pt-SnO_{2-x}$ thin film device (Pt thickness : $43{\AA}$) to 6000 ppm CO shows the sensitivity of 80% and high selectivity to CO. And the operating temperature and the thermal oxidation temperature of $Pt-SnO_{2-x}$ thin film device with high sensitivity to CO were $200^{\circ}C$ and $500^{\circ}C$, respectively.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.445-450
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• 1997

An ammonia gas sensor with high sensitivity using thick-film technology were fabricated and examined. The material for sensing the ammonia gas was the mixture of oxide semiconductor, $FeO_{x}-WO_{3}-SnO_{2}$. The sensor exhibits resistance increase upon exposure to low concentration of ammonia gas. The resistance of the sensor is decreased, on the other hand, for exposure to reducing gases such as ethyl alcohol, methane, propane and carbon monoxide. A novel method for detecting ammonia gas quite selectively utilizing a sensor array consisting of an ammonia gas sensor and a compensation element were proposed and developed. The compensation element is a Pt-doped $WO_{3}-SnO_{2}$ gas sensor which shows opposite direction of resistance change in comparison with that of the ammonia gas sensor upon exposure to ammonia gas. Excellent selectivity has been achieved using the sensor array having two sensing elements.

• Korean Journal of Social Welfare Studies
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• v.42 no.2
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• pp.97-122
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• 2011

After global economic crisis, most countries increased the welfare expenditure as a part of stimulus package. As a However welfare expenditure was decreased radically as the crisis was transmitted into the financial crisis. Which turning point is the welfare state going through now? Although the need for the welfare and the role of the state to take responsibility of public welfare has increased because of poverty and polarization, responses of the state against the crisis had focused on the aid to the financial industry and cutting taxes and showed limitations in coordination. Financial limitation of welfare expenditure, political individualism, the change of class politics and the mixture of the welfare institutions and financial institutions make have a pessimistic prospect of the retrenchment to the minimalist welfare state. As neoliberal state is continued cash benefits mainly for the middle class is being decreased. As a result, the direction the welfare states pursue is prospected to win over the poor by strengthening selectivity in welfare provision rather than class coordination.