• Journal of Mechanical Science and Technology
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• v.15 no.8
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• pp.1181-1187
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• 2001

The radiation driven response function (R$\_$q/) for AP and HMX propellant was obtained and compared with experimental results by using a simple $\alpha$$\beta$γ flame model rather than with detailed chemistry. For an AP propellant, the profile of heat release was assumed by the experimental data. The calculated R$\_$q/ shows a frequency shift of the peak amplitude to the higher frequency and a decrease in the maximum amplitude as radiation increases. In addition, it was found the increase in the total flux could enhance the mean burning rate γ$\_$b/ while the phase differences between the radiation and resulting conduction could consequently reduce the fluctuating amplitude Δγ$\_$b/. Fortunately, this is the qualitative duplication of the behavior recently observed in the experiments of RDX propellants. For HMX, the response function R$\_$q/ has been calculated and showed a quite good agreement with the experimental data. Even though the fairly good agreement of R$\_$q/ with experimental ones, the unsteady behavior of HMX was not reproduced as the radiation input increased. This is due to lack of the material properties of HMX or the physical understanding of HMX burning at high pressure.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.1
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• pp.12-19
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• 2020

Objective: The appropriate function of the hypothalamic-pituitary-gonadal axis is essential for maintaining proper reproductive function. In female mammals, the hypothalamic-pituitary-gonadal axis regulates reproductive changes that take place in the estrus cycle and are necessary for successful reproduction. This study was conducted to investigate the effect of thymectomy on the estrus cycle in neonatally thymectomized guinea pigs. Methods: In this study, 12 female guinea pigs, six thymectomized and six sham-operated, were studied. The effects of neonatal thymectomy at 5-7 days of age on parameters of the reproductive axis were examined in female guinea pigs. Gonadotropin and 17β-estradiol levels were assessed at regular intervals (days 0, 3, 6, 9, 12, and 15) of the estrus cycle, and the time of vaginal opening in the thymectomized and shamoperated guinea pigs was determined. Results: Significant reductions in gonadotropins and 17β-estradiol levels during estrus cycle were found in neonatally thymectomized female guinea pigs compared to sham-operated guinea pigs. Conclusion: The results of this study underscore the importance of the thymus in the neonatal period for normal female reproductive function.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.240-247
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• 2009

The results of performance analysis by adopting the channel scenarios characterized as Weibull fading for an multicarrierdirect sequence-coded division multiple access (MC-DS-CDMA) system are proposed in this investigation. On the other hand, an approximate simple expression with the criterion of bit error rate (BER) versus signal-to-noise ratio (SNR) method is derived for an MC-DS-CDMA system combining with maximal ratio combining (MRC) diversity based on the moment generating function (MGF) formula of Weibull statistics, and it associates with an alternative expression of Gaussian Q-function. Besides, the other point of view on the BER performance evaluation of an MC-DS-CDMA system is not only the assumption of both single-user and multi-user cases applied, but the phenomena of partial band interference (PBI) is also included. Moreover, in order to validate the accuracy in the derived formulas, some of the system parameters, such as Weibull fading parameter (${\beta}$), user number (K), spreading chip number (N), branch number (L), and the PBI (JSR) values, etc., are compared with each other in the numerical results. To the best of author's knowledge, it is a brand new idea which proposes the evaluation of the system performance for an MC-DS-CDMA system over the point of view with Weibull fading channel.

• Journal of Power Electronics
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• v.18 no.1
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• pp.1-10
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• 2018

Recently, the nine-switch inverter has been proposed as a dual output inverter. To date, studies on the control strategies for NSIs have been mostly combined with their application. However, in this paper, a mathematical model and control strategy for nine-switch inverters has been proposed in view of the topology. A switching function model and equivalent circuit model of a nine-switch inverter have been built in ${\alpha}{\beta}$ coordinates. Then, a novel current observer with an improved integrator is proposed based on the switching function model, and a direct power control strategy is proposed. No current sensors are used in the proposed strategy, and only two voltage sensors are employed. The performance of the proposed control method is verified by simulation and experimental results.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.14 no.3
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• pp.371-381
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• 2007

Purpose: This study was done to investigate the relationship of family function, self-esteem, life satisfaction, and general characteristics to loneliness in community dwelling Korean elders and identify factors affecting loneliness. Method: With a cross-sectional causal-relationship design and a convenience sample, 205 elders residing in three districts of the city of Seoul, S. Korea were recruited. Participants were assessed using the Family APGAR Score, Self-Esteem Scale, Life-Satisfaction Scale, and Revised UCLA Loneliness Scale. Results: The mean score for degree of loneliness (Mean=39.61, SD=10.09) was just below the mean for the scale (Possible range 20-80). Loneliness had significant negative correlations with family function (r= -.400, p<.001), self-esteem (r= -.399, p<.001), and life satisfaction (r= -.644, p<.001). Other general characteristics that had significant or nearly significant relationships with loneliness were perceived current financial and health status, whether doing any exercise or physical activities, degree of close relationship with family members, and length of living in current residence. Among variables, life satisfaction (Standardized ${\beta}\;=\;-.589$, p<.001) and length of living in current residence (Standardized ${\beta}\;=\;-.136$, p<.05) significantly predicted degree of loneliness. Conclusion: Findings of this study allow a comprehensive understanding of loneliness and related factors among community dwelling elders in Korea. However, further studies with a larger random sample from various living environments are necessary.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3248-3252
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• 2012

Vibrio extracellular metalloprotease (vEP), secreted from Vibrio vulnificus, shows various proteolytic function such as prothrombin activation and fibrinolytic activities. Premature form of vEP has an N-terminal (nPP) and a C-terminal (C-ter100) region. The nPP and C-ter100 regions are autocleaved for the matured metalloprotease activity. It has been proposed that two regions play a key role in regulating enzymatic activity of vEP. Especially, C-ter100 has a regulatory function on proteolytic activity of vEP. C-ter100 domain has been cloned into the E. coli expression vectors, pET32a and pGEX 4T-1 with TEV protease cleavage site and purified using gel-filtration chromatography followed by affinity chromatography. To understand how C-ter100 modulates proteolytic activity of vEP, structural studies were performed by heteronuclar multi-dimensional NMR spectroscopy. Backbone $^1H$, $^{15}N$ and $^{13}C$ resonances were assigned by data from standard triple resonance and HCCH-TOCSY experiments. The secondary structures of vEP C-ter100 were determined by TALOS+ and CSI software based on hydrogen/deuterium exchange. NMR data show that C-ter100 of vEP forms a ${\beta}$-barrel structure consisting of eight ${\beta}$-strands.

• Geotechnical Engineering
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• v.4 no.3
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• pp.5-18
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• 1988

This study aims at scrutinizing the relationships among the frequency distribution of voids the relative density and the shear strength for the three types of different granular materials. The main results summarized are as follows: (1) The frequency distribution of void ratio of glass beads can be approximated by the negative exponential distribution proposed by Shahinpoor (1981), while as the particle shape changes from spherical to angular the frequency of the denser voids decreases and the distributions are well presented by the beta distribution. (2) For all materials, the standard deviation of void ratio increases with decreasing both the relative density of the material and sphericity of particle. (3) It was found that shear strength of the material was a function of not only the mean void ratio and its standard deviation, but also of the shape of the probability density function of the distribution of void ratio. The more the frequency distribution of void inclines towards the denser voids, the higher the shear strength of the material and vice versa.

• The Journal of Pediatrics of Korean Medicine
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• v.21 no.2
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• pp.1-12
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• 2007

Objectives : Allergic children have known to have multiple behavior problems. Among them, attentional ability disorder is one of the most common problems. This study is to examine relationship between learning ability and allergic rhinitis by analyzing EEG status of children. Methods : We analyzed cognitive functions of two different children groups; 21 children with allergic rhinitis and 19 normal children with CANS 3000(Central & Autonomic Nervous System, LAXTHA Inc., Korea), cognitive functions assessment program by EEG. Results : 1. According to mean active EEG rhythm of Theta, Alpha, SMR, M-beta, there were no significant difference between allergic rhinitis and the normal group. 2. According to mean active EEG rhythm of right H-beta, Gamma wave allergic rhinitis group's value was significantly higher than that of the normal group. 3. According to mean cognitive strength, response, concentration, left / right brain activity and learning ability score, there were no significant difference between allergic rhinitis and the normal group. 4. According to mean workload score, allergic rhinitis group's value was significantly higher than that of the normal group. Conclusions : It is likely that allergic rhinitis group, which showed relatively high frequency EEG rhythm, is more fragile to stress and less active on mental processing. Along side with physical examination, psychological assessment should also be conjugated on treating children with allergic rhinitis.

• Journal of the Korean Chemical Society
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• v.31 no.3
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• pp.207-214
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• 1987

Rates of solvblysis of benzyl chloride in ethanol-water mixtures have been measured at 30 and $40^{\circ}C$ under various pressures up 1.6 kbar. The plots of 1n k as a function of pressure are fitted to a second order function in p, and values of ${\Delta}V^{\neq}$and ${\Delta}{\beta}^{\neq}$ are obtained from the results. Also the values of various pseudo thermodynamic quantities were evaluated from the rate constants. The relationships of the 1n k to $Q_w$ or 1n $C_w$ indicate that the reaction proceeds through $S_N1$ mechanism. A comparison between the present and the previous results gives that the increasing order of ${\mid}{{\Delta}V_0}^{\neq}{\mid}$ and n-values are $p-Cl>p-H>p-CH_3$ and $p-CH_3>p-H.p-Cl$, respectively. From these results, it is believed substituent such as the $p-CH_3$group favors the $S_N1(1)$ character, while the p-Cl group leads to the $S_N1(2)$ character.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4397-4402
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• 2011

The NF-${\kappa}B$ system of transcription factors plays a crucial role in inflammatory diseases, making it an important drug target. We combined quantitative structure activity relationships for predicting the activity of new compounds and quantitative dynamic models for the NF-${\kappa}B$ network with intracellular concentration models. GFA-MLR QSAR analysis was employed to determine the optimal QSAR equation. To validate the predictability of the $IKK{\beta}$ QSAR model for an external set of inhibitors, a set of ordinary differential equations and mass action kinetics were used for modeling the NF-${\kappa}B$ dynamic system. The reaction parameters were obtained from previously reported research. In the IKKb QSAR model, good cross-validated $q^2$ (0.782) and conventional $r^2$ (0.808) values demonstrated the correlation between the descriptors and each of their activities and reliably predicted the $IKK{\beta}$ activities. Using a developed simulation model of the NF-${\kappa}B$ signaling pathway, we demonstrated differences in $I{\kappa}B$ mRNA expression between normal and different inhibitory states. When the inhibition efficiency increased, inhibitor 1 (PS-1145) led to long-term oscillations. The combined computational modeling and NF-${\kappa}B$ dynamic simulations can be used to understand the inhibition mechanisms and thereby result in the design of mechanism-based inhibitors.