• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4039-4045
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• 2014

The crystallization behavior of irradiated polypropylene (PP) and the blend is an important parameter for polymer processing. Blends of PP/low density polyethylene (LDPE) with different LDPE contents were prepared by melt mixing in a twin screw extruder. The effect of the LDPE content on the irradiation effectiveness of the PP/LDPE blend with trimethylolpropane-trimetacrylate (TMPTMA) as a crosslinking co-agent was investigated in conjunction with the LDPE loading in the blend. The non-isothermal crystallization and crystal structure were measured by DSC, X-ray diffraction (XRD), and polarized optical microscopy (POM). A decrease in the melting temperature of PP was observed due to irradiation, which may be due to the PP chain scissioning effect of irradiation. The Ozawa component n represents a rod shaped, disc shaped and sphere-shaped geometry of the crystal if the value corresponds to 2, 3 and 4, respectively. Based on Ozawa analysis, the values of n were 3.8 and 2.3 for the pure PP and PP blends with 30 wt% LDPE, respectively. The fact that the crystal geometry of PP changed from spherical to disc and rod shaped was confirmed by Ozawa analysis and POM. The ${\beta}$ form XRD peak of the PP/LDPE blend at $16.1^{\circ}$ disappeared after irradiation due to the crosslinking reaction.

• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.105-111
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• 2008

A pelagic tuna longline research cruise in the eastern and central Pacific Ocean from September to October of 2006 was conducted to compare catch rates with the use of different hook type and bait combinations. Traditional tuna hooks (J 4) and three circle hook types (C15, C16, C18), along with five bait types (chub mackerel (CM), jack mackerel (JM), milkfish (MF), sardine (SD), and squid (SQ)) and hook number as a proxy for hook depth were evaluated for their effect on bigeye tuna catch rates (fish per 1,000 hooks) using Generalized Linear Models (GLMs). Results from 28 sets indicated significant differences in bigeye catch rates between individual longline sets and hook number. The GLM explained 33% of the deviance in bigeye catch rates with these two factors. An alternative model formulation included bait type which had a small effect (explaining 2.7% of the deviance) on catch rates. Hook type had a negligible and non-significant effect in the GLMs. These results indicate that all of the hooks and baits tested are equally effective at catching bigeye tuna and that hook number (depth) was the paramount operational factor in explaining bigeye tuna catch rates.

• Korean Journal of Legislative Studies
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• v.24 no.1
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• pp.203-239
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• 2018

Responsible government can be achieved when social cleavages are institutionalized via political competition and social interests are represented by responsible parties. This paper aims to investigate the factors that determine welfare expenditures in Korean local governments by analyzing partisanship and political competition factors simultaneously in the same model. This paper also argues that the relationship between the political factors and welfare expenditures in local governments is not linearly increasing as the previous studies claim. This paper examines the welfare expenditures in Korean municipality-level local governments in 2007, 2011, and 2015. The primary findings are: 1) the partisanship of the head of local government and the party distribution of local assembly members have meaningful effect on the welfare expenditures and the divided governments do not show significantly different effect on welfare expenditures from unified governments, which is contrary to the extant studies, 2) the partisan effects of the head and the local assembly vary according to the levels of municipalities (Gu, Gun, and city), mainly due to the difference in types of revenues and expenditures and 3) the relationship between seats shares of progressive parties in local assembly and the welfare expenditure is not linearly increasing one. The effect of seats shares of progressive parties dramatically begins to increase when the seats shares are in 40%-60%. With these findings, this paper highlights the conservative nature of head of local governments with Hannara party (or Saenuri Party), the conservative leaning of independent candidates, and the conservative orientation of local assemblies in the regions dominated by Democratic Party (and its equivalents).

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.5
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• pp.1-11
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• 2019

Financing plays an important role in the survival and growth of startups. This study investigates key factors that improve startup financing performance. To this end, we analyze the relationship between the proportion of intellectual property and the financing performance. In addition, this study also examine the impact of the founder's education level on the financing of startups, and the moderating effect of the founder's education level on the relationship between intellectual property proportion and financing. Based on the survey data of 331 startups, this study found that the proportion of intellectual property and the financing performance have an inverted U-shaped nonlinear relationship. While the founder's education level has a positive impact on the financing performance, it negatively moderate the relationship between the intellectual property proportion and the financing performance. Through these findings, this study suggests that it is necessary to maintain an adequate proportion of intellectual property in order to maximize startup financing performance. The higher education level of founder enhances the startup financing. Since the founder's education level weaken the effect of intellectual proporty's effect on startup financing, however, startups need to control the proportion of intellectual property to improving financing according to the founder's education level. Based on signal theory, this study proposes a new strategy of intellectual property to enhance startup financing performance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.293-308
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• 2012

The shear behavior at the particle/surface interface such as rock joint can determine the mechanical behavior of whole structure. Therefore, a fundamental understanding of the mechanisms governing its behavior and accurately estimation of the interface strength is essential. In this paper, PFC, a numerical analysis program of discrete element method was used to investigate the effects of the surface roughness on interface strength. The surface roughness was characterized by smooth, intermediate, and rough surface, respectively. In order to investigate the effects of particle shape and crushing on particle/surface interface behavior, one ball, clump, and cluster models were created and their results were compared. The shape of particle was characterized by circle, triangle, square, and rectangle, respectively. The results showed that as the surface roughness increases, interface strength and friction angle increase and the void ratio increases. The one ball model with smooth surface shows lower interface strength and friction angle than the clump model with irregular surface. In addition, a cluster model has less interface strength and friction angle than the clump model. The failure envelope of the cluster model shows non-linear characteristic. From these findings, it is verified that the surface roughness and particle shape effect on the particle/surface interface shear behavior.

• Journal of Korea Water Resources Association
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• v.48 no.12
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• pp.1023-1035
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• 2015

This study applies 3-D N-S solver based on PBM (Porous Body Model), LED-WASS-3D ver 2.0 to directly analyze non-linear interaction of seawater-freshwater-coastal aquifer in order to simulate the seawater infiltration into coastal aquifer. This numerical simulation is the first trial in Korea, as well as unusual and new numerical analysis abroad. Firstly, to validate the applied numerical model, the validity and effectiveness was verified for the numerical model by comparing and considering it with the result of laboratory experiment for seawater-freshwater interface in coastal aquifer. And then it simulated the seawater infiltration into coastal aquifer considering the changed levels of seawater and groundwater in order to analyze the distribution characteristics of flow field and seawater-freshwater interface of coastal aquifer as the level difference between seawater and groundwater and rate of seawater level (${\Delta}h/h$) increased. In addition, the characteristics of seawater infiltration were analyzed from the vertical salinity in the coastal aquifer by ${\Delta}h/h$, which cannot be obtained from existing non-diffusion numerical models. Finally, it analyzed the effect of ${\Delta}h/h$ on the seawater infiltration distance in coastal aquifer, which was indexed.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.156-162
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• 2007

The parallel beam SPECT system acquires projection data by using collimators in conjunction with photon detectors. The projection data of the parallel beam SPECT system is, however, blurred by the point response function of the collimator that is used to define the range of directions where photons can be detected. By increasing the number of parallel holes per unit area in collimator, one can reduce such blurring effect. This approach also, however, has the blurring problem if the distance between the object and the collimator becomes large. In this paper we consider correction methods for artifacts caused by non-circular orbit of parallel beam SPECT with many parallel holes per detector cell. To do so, we model the relationship between the object and its projection data as a linear system, and propose an iterative reconstruction method including artifacts correction. We compute the projector and the backprojector, which are required in iterative method, as a sum of convolutions with distance-dependent point response functions instead of matrix form, where those functions are analytically computed from a single function. By doing so, we dramatically reduce the computation time and memory required for the generation of the projector and the backprojector. We conducted several simulation studies to compare the performance of the proposed method with that of conventional Fourier method. The result shows that the proposed method outperforms Fourier methods objectively and subjectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.845-854
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• 2003

In this paper, the characteristics of compensation for WDM channel signal distortion due to both chromatic dispersion and Ken effect in 1,000 km 200 Gbps(5${\times}$40 Gbps) WDM systems was investigated. The WDM system has a path-averaged intensity approximation(PAIA) mid-span spectral inversion(MSSI) as a compensation method. This system has a highly nonlinear dispersion shifted fiber(HNL-DSF) optical phase conjugator(OPC) in the mid-way of transmission line. In order to evaluate the degree of compensation, 1 dB eye opening penalty(EOP), bit error rate(BER) characteristics and power penalty of 10$\^$-9/ BER are used. It is confirmed that HNL-DSF is an useful nonlinear medium in OPC fur wideband WDM system with PAIA MSSI and that the optimal compensation for WDM channel distortion is achieved by the selection of pump light power of OPC, which equalize the conjugated light power into the second half fiber section with the input WDM signal light power depending on total transmission length, dispersion coefficient of fiber, OPC pump light wavelength, conversion efficiency of WDM channel in OPC.

• Journal of agricultural medicine and community health
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• v.23 no.2
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• pp.287-293
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• 1998

Although serum gamma-glutamyl transferase(GGT) has been widely used as a marker of alcoholic hepatic dysfunction, little is known as to behavioral correlates in the normal population. To examine the association between serum GGT activity and some behavioral factors in male rural population, data un health examination in a rural population (248 males aged 40 years and older) was analyzed Multiple linear regression and analysis of convariance were used to control the effect of confounding factors. Adjusted average differences in the level of serum GGT according to body mass index(BMI: $kg/m^2$) and alcohol intake(ml/day) were statistically significant(p=0.051 0<0.001 respectively). Serum GGT activity for BMII$\geq$25 was significantly higher than for BMI<25 in non-drinkers(p=0.007), but not significantly different in drinkers(p=0.892). Alcohol intake was significantly associated with elevated serum GGT activity for both BMI$\geq$25 and BMI<25(p<0.001, p=0.002 respectively). These findings suggest that alcohol drinking, obesity in non-drinkers are important factors associated with serum GGT in male rural population.

• Korean Journal of Clinical Pharmacy
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• v.29 no.2
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• pp.89-100
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• 2019

Background: Invasive aspergillosis (IA) is associated with high morbidity and mortality, particularly among immunocompromised patients, such as lung transplant recipients. Voriconazole, the first-line therapy for IA, shows a non-linear pharmacokinetic profile and has a narrow therapeutic range. Careful and appropriate administration is necessary, primarily because it is used for critically ill patients; however, the clinical usefulness of therapeutic drug monitoring (TDM) has not been sufficiently verified. Therefore, in this study, we validated the safety and efficacy of voriconazole TDM in lung transplant recipients receiving only voriconazole for IA treatment. Methods: The electronic medical records of lung transplant recipients (${\geq}19$ years of age) administered only voriconazole for > 7 days for treatment of IA from June 1, 2013 to May 31, 2018 were analyzed retrospectively. Results: Among the 54 patients, 27 each were allocated to TDM and non-TDM groups, respectively. There were no significant differences in patient characteristics between the two groups except for ICU-hospitalization status. Of the TDM group patients, 81.5% needed adjustment of voriconazole dosage because the levels were out of target range. Comparison of two groups showed that treatment response was higher throughout treatment and switching rates of second-line agents were significantly lower in the TDM group, but it was insufficient to confirm safety improvements through voriconazole TDM. Conclusions: Considering that the treatment response tended to be higher and the rates of switching to second-line antifungal agents were lower in the TDM group, voriconazole TDM may increase the therapeutic effect on IA in lung transplant patients.