• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.1
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• pp.73-83
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• 1997

Most of the materials used in various industrial fields and also in our daily life are multi-component materials or composite materials, and it is well known that there are many cases where adhesion between the constituents within the bonded systems plays an important role. There are various types of performance evaluation tests for the bonded materials, among which tests for evaluating the bond performance under various conditions may be regarded as the most interesting ones for those engaged in work related to adhesion. I have studied on the mechanism of adhesion form the rheological standpoint with my colleagues, including some students from Korea, and I am very happy to be able to have a talk on some of our research works. In Japan, the so-called "adhesives" are usually classified into two categories;adhesives and pressure sensitive adhesives (PSA). Adhesives are the materials which solidify after bonding and are after used as the structural adhesives because the adhesive strength is comparatively strong. On the other hand, the pressure sensitive adhesives never solidify and are used as PSA tapes, labels or decals. About the adhesives, we have examined the dependence of adhesive strength(shear, tensile, peel) upon both temperature and rate of deformation, and found out some empirical rules which are applicable to most of the adhesive systems. We have also developed a simplified theory of adhesion, which is deseribed in terms of mechanical equivalent mode1 and a few failure criteria. Although some of the common rules can be accounted for according to this theory, it must be pointed out that a fracture mechanical approach ms inevitable especially in the region where the meehanical relaxation time of the adhesive is extremely large [W. W. Lim and H. Mizumachi]. About the pressure sensitive adhesives, we have studied on the PSA performance (peel, tack, holding power) as a function of both the viscoelastic properties and surface chemical properties of the materials, and found out some rules, and again we have developed a theory which deseribes the mechanism. And in addition, we have studied on the miscibility between linear polymers and oligomers, because PSA is generally manufactured by blending gums and tackifier resins. Many phase diagrams have been found and some of them have been analyzed on thermodynamic basis, and it became evident that the miscibility is a very important factor in PSA [H. J. Kin and H. Mizumachi]. In this presentation, I want to emphasize the fact that the adhesion performance is closely related to the structure/property of the adhesives.adhesives.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.196-203
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• 1993

Emulsions were prepared with the inversion emulsification method which adopted the agent-in-oil method-dissolving the mixed surfactants composed of the glycerin monostearate, polyoxyethylene(100) monostearate, and polyoxyethylene(20) sorbitan monostearate into mixtures of liquid paraffin and beeswax, and adding the aqueous solution of propylene glycol, gradually-and then their phases and viscosities behaviors in the emulsifying process were investigated. The fine and homogeneous o/w emulsions were formed in the HLB region (HLB 10.1~12.3), showing liquid crystalline phase and white gel phase in the emulsifying process. The phase inversion steps in the emulsifying process appeared as follows, i.e., oil continuous phase${\rightarrow}$liquid crystalline phase${\rightarrow}$white gel phase${\rightarrow}$o/w emulsion. Shear rate-shear stress curves of the prepared emulsions had the yield values which pointed out the existence of inner structure between emulsion particles, and the hysteresis loop which showed that the inner structure wasbroken irreversibly by the shear. The area of hystersis loop, an index of breakdown of inner structure, was increased with the decreasing of the HLB value of emulsifier, Shear time-shear stress curves showed the time dependence of plastic viscosity, and the relaxation time in time thinning behavior(${\lambda}$) indicated that the stability of emulsions prepared with the inversion emulsification method was decreased with the increasing of HLB values of emulsifier and was higher than that of emulsions prepared by homomixer.

• Journal of Food Hygiene and Safety
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• v.28 no.4
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• pp.367-375
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• 2013

Kalopanax pictus has pharmacologically anti-inflammatory and analgesic effect and is known to respond to treatment of backache, knee pain and etc. In this study, we investigated the effects on gastric lesions of Kalopanax pictus both from Korea (KPK) and China (KPC) compared with their related origin, Znthoxylum ailanthoide both from Korea (ZAK) and China (ZAC), and Korean Bombax malabaricum (BMK). In preliminary screening, KPK and KPC shown effective inhibition of HCI EtOH-induced gastritis in rats. To elucidate their protective effects on gastric lesions, we assessed inhibition of H. pylori colonization, 2,2-diphenyl-1-picrylhydrazyl(DPPH) radical scavenging activities, reducing power test, and inhibition of lipid peroxidation. KPK was the most effective from antioxidant assays. KPK also shown the inhibition of indomethacin-induced gastric ulcer in rats. Gastric secretion in rats, KPK reduced the secretion of gastric juice and total acidity and raised pH. Therefore, it is possible that KPK can be developed as health functional food and natural medicine. In addition, it can contribute to the standardization with objectivity and reliability for KPK through the criteria establishment of the precise origin of medicine, the prevention of indiscriminate distribution of imitation, and the rising rate of dependence on imports of medicinal herbs, and mixing prevention of low-quality goods.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.67-71
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• 2003

Alginates were irradiated in an aqueous solution with $Co^{60}$ gamma rays in the dose ranges from 0 to 100 kGy, and investigated the relationship between the intrinsic viscosity $([{\eta}])$ and the molecular weight $(M_w)$ of alginates. The molecular weight of alginate was measured by gel permeation chromatography and the ranges from 1,894 to 135,174 Da were obtained. The molecular weight of alginate decreased markedly with increasing the degree of ${\gamma}-ray$ dose rate. The intrinsic viscosity of alginate solution after ${\gamma}-irradiation$ showed the ranges from 9.83 (g/g) to 602.69 (g/g), depending upon the ${\gamma}-irradiation$ dose. The molecular weight of alginate dependence of the intrinsic viscosity of the alginate solution would be expressed by Mark-Houwink equation. With a linearization of molecular weight and the intrinsic viscosity of the alginate solution, Mark-Houwink equation could be expressed with constant variables and the real data fitted to the equation of $[{\eta}]=2.2{\times}10^{-6}\;{M_w}^{1.656}\;(R^2=0.998)$.

• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.1-15
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• 2018

Passive microwave sea surface temperatures (SST) were validated in the Northwest Pacific using a total of 102,294 collocated matchup data between Global Precipitation Measurement (GPM) / GPM Microwave Sensor(GMI) data and oceanic in-situ temperature measurements from March 2014 to December 2016. A root-mean-square (RMS) error and a bias error of the GMI SST measurements were evaluated to $0.93^{\circ}C$ and $0.05^{\circ}C$, respectively. The SST differences between GMI and in-situ measurements were caused by various factors such as wind speed, columnar atmospheric water vapor, land contamination near coastline or islands. The GMI SSTs were found to be higher than the in-situ temperature measurements at low wind speed (<6 m/s) during the daytime. As the wind speed increased at night, SST errors showed positive bias. In addition, other factors, coming from atmospheric water vapor, sensitivity degradation at a low temperature range, and land contamination, also contributed to the errors. One of remarkable characteristics of the errors was their latitudinal dependence with large errors at high latitudes above $30^{\circ}N$. Seasonal characteristics revealed that the errors were most frequently observed in winter with a significant positive deviation. This implies that SST errors tend to be large under conditions of high wind speeds and low SSTs. Understanding of microwave SST errors in this study is anticipated to compensate less temporal capability of Infrared SSTs and to contribute to increase a satellite observation rate with time, especially in SST composite process.

• Journal of Korea Port Economic Association
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• v.35 no.4
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• pp.169-186
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• 2019

This study suggests a development direction by comparing the cargo throughput of the port of Yeosu-Gwangyang during 2007-2015 with that of domestic ports. It derived a concentration index (HHI) of cargo throughput in domestic ports by Yeosu-Gwangyang port docks, shipping companies, and abroad regions. The main results were as follows. First, in terms of total cargo handled, the port of Yeosu-Gwangyang was second only to the port of Busan, and the HHIs for the past nine years were relatively low. Second, the port of Yeosu-Gwangyang ranked first for total import and export cargo throughput, showing relatively stable HHIs from 2007 to 2015. Third, the HHIs of container handling performance by national shipping companies showed stable levels below 1,800. Fourth, there were no regions where cargo volume was noticeably concentrated in the port of Yeosu-Gwangyang, and it showed cargo throughput across various abroad regions. While changes in national shipping companies are expected after the Hanjin Shipping Crisis, there should be no serious concern regarding the dependence of the port of Yeosu-Gwangyang. It is expected to develop further by realizing the full use of all its facilities, diversifying the tenants in the Yeosu-Gwangyang area, and improving the demurrage rate.

• Membrane Journal
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• v.12 no.2
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• pp.97-106
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• 2002

Small angle light scattering (SALS) and field emission scanning electron microscope (FE-SEM) have been used to investigate the light scattering patterns with time evolved during water vapor quenching (relative humidity of 53 (${\pm}3)%$ at $26^{\circ}C$ of polysulfone (PSf)/NMP/Alcohol and chlorinated poly(vinyl chloride) (CPVC)/THF/Alcohol, respective1y. Time dependence of the position of the light scattering maximum was observed at PSf dope solutions, confirming spinodal decomposition (SD), while CPVC dope solutions showed a decreased scattered light intensity with an increased q-value, indicating nucleation & growth (NG). For the each system, domain growth rate in the intermediate and late stage of phase separation decreased with increasing the number of carbon of alcohol used as additive (non-solvent). Also, in the early stage for SD, the scattering intensity with time was in accordance with Cahn's linear theory of spinodal decomposition, regardless of types of non-solvent additive. Also, the size scales obtained by SALS were mutually compared to domain sizes gained by FE-SEM measurement. These observations of scattering pattern were much clearly observed for the 20PSf/70NMP/10n-butanol (w/w%) and agreed with the theoretical predictions for scattering patterns of each stage like the early, the intermediate, and the late stage of SD type phase separation. As the scattering maximum was observed at the larger angles (larger q) in the order of n-butanol > n-propanol > methanol > no alcohol, the pore size of final morphology decreased.

• The Journal of Society for e-Business Studies
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• v.25 no.4
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• pp.77-109
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• 2020

In this paper, we build a gradient Boosting model to predict government SME R&D subsidy, select features of high importance, and measure the impact of each features to the predicted subsidy using PDP and SHAP value. Unlike previous empirical researches, we focus on the effect of the R&D subsidy distribution pattern to the incentive of the firms participating subsidy competition. We used the firm data constructed by KISTEP linking government R&D subsidy record with financial statements provided by NICE, and applied a Gradient Boosting model to predict R&D subsidy. We found that firms with higher R&D performance and larger R&D investment tend to have higher R&D subsidies, but firms with higher operation profit or total asset turnover rate tend to have lower R&D subsidies. Our results suggest that current government R&D subsidy distribution pattern provides incentive to improve R&D project performance, but not business performance.

• Journal of Digital Convergence
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• v.15 no.2
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• pp.27-33
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• 2017

The problem of social adaptation of North Korean defectors is becoming increasingly important, as its core significance shifted from welfare to the preparatory stage of United Korea. Hence, this research tries to comprehend the 'factors that enhance their social adaptation'. For this end, by theoretically considering, support resources centered around economic goals did indeed increase the employment rate, but the 'premature social adaptation' did not help them form their own social identity. This led the employment to become another form of social failure and difficulty in social adaptation. Furthermore, by going through interview, the importance of 'social dependence' is emphasized and it was shown that it was 'relationship' that affects both social adaptation and difficulty in social adaptation. Accordingly, this research suggests that it is vital to make a communicative environment in which South and North Korean citizens can freely communicate. This will not only lead to enhancement of social adaptation to South Korean society, unsolvable by economic independence, but it will also lead to more effective 'economic support' policies.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.217-223
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• 2010

We grew multi-stacked InAs/$In_{0.1}Ga_{0.9}As$ DWELL (dot-in-a-well) structure by metal organic chemical vapor deposition and investigated optical properties by photoluminescence and I-V characteristics by dark current measurement. When stacking InAs quantum dots (QDs) with same growth parameter, the size and density of QDs were changed, resulting in the bimodal emission peak. By decreasing the flow rate of TMIn, we achieved the uniform multi-stacked QD structure which had the single emission peak and high PL intensity. As the growth temperature of n-type GaAs top contact layer (TCL) is above $600^{\circ}C$, the PL intensity severely decreased and dark current level increased. At bias of 0.5 V, the activation energy for temperature dependence of dark current decreased from 106 meV to 48 meV with increasing the growth temperature of n-type GaAs TCL from 580 to $650^{\circ}C$. This suggest that the thermal escape of bounded electrons and non-radiative transition become dominant due to the thermal inter-diffusion at the interface between InAs QDs and $In_{0.1}Ga_{0.9}As$ well layer.