• Journal of Food Hygiene and Safety
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• v.13 no.2
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• pp.171-187
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• 1998

Garlic occupies a special position among the many foods of vegetable origin because it is the sole food for Koreans during the their lives. And vitamin A has been ingested by forms of food or additives. Cadmium has been described as one of the most dangerous trace elements in the food and environment of man and livestocks. Since the de novo synthesis of stress proteins can be detected early after exposure to some agents, analysis of cadmium-induced changes in gene expression , ie. alterations in patterns of protein synthesis, may be useful to develop as biomarkers of exposure and damage for food hygiene. He acute and chronic combine effects of cadmium (Cd, CdCl2 20mg/kg), garlic oil(Dds: diallyl disulfide 50mg/kg, 3 times a week) and vitamin A(Ra: retinol acetate 50,000 IU/kg, 3 times a week) on Wistar male rats were evaluated concerning cadmium contents, tissues enzyme activity, HSP expression histopathological and electron microscopical examinations. The results of the study are as follows ; 1. Less cadmium was absorbed through the digestive tracts, but the ratio of contents in tissue were not changed by the simultaneous adminstration of diallyl disufide or retinol acetate. 2. ALT(alanine aminotransferase) , AST(aspartate aminotransferase), glucose, BUN (blood urea nitrogen), creatinine, the key indices of the clinical changes in hepatic and renal function were significantly hanged by the cadmium treatment after 1 week in liver, after 4 weeks in kidney. 3. Histopathological changes in cadmium treated rats were appeared at 8 weeks age treatment in kidneys. Homogenous eosinophilic material was accumulated in cortical and collecting tubular lumens at 16 weeks. Degenerated or necrotized tubular cells were observed in cortex and medulla. Degenerated seminiferous tubules and homogeneous eosinophilic material was seen in interstitial tissue of rat treated with cadmium for 16 weeks. Calcium deposits were seen in degenerated seminiferous tubules and the tubules showed severe calcification of rat treated with cadmium for 16 weeks. Electron microscope changes in kidney were observed in rats treated with CdCl2 20 mg/kg. Proximal convoluted tubule cells showed selling of cytoplasm and narrow lumen. Capillary endothelial cells showed cytoplasmic vacuoles and swelling. Degenerated epithelial cells were accumulated in tubular lumen of kidney. 4. Enhanced synthesis of 70 KDa relateve molecular mass proteins were detected in 2 hours after cadmium, exposure, with maximum activity occurring at 8~48 hours. Induction of HSP 70 was evident at proximal tubules and glomeruli in kidney. Testicular cells produced enough HSP to be detected normally. From the above results, it could be concluded that HSP70 induction by the cadmium treatment was a rapid reaction to indicated the exposure of xenobiotics, and retinol acetate reduced the cadmium induced nephrotoxicity.

• Analytical Science and Technology
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• v.6 no.1
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• pp.107-119
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• 1993

The purpose of this study is to investigated the elution behavior of platinoid metal acetylacetonates, which is the key to elucidate their retention mechanism and optimize their RPLC separation conditions. The retention data of four platinoid metal acetylacetonates have been measured on four different columns in methanol-water and acetonitrile-water systems. The retention of uncharged platinoid metal acetylacetonates is interpreted by solvophobic effect. The retention of platinoid metal acetylacetonates is also greatly influenced by the geometric structure of the complexes. The square planar chelates, $Pd(acac)_2$, $Pt(acac)_2$, are retained longer than the octahedral chelates, $Rh(acac)_3$, $Ir(acac)_3$. It is likely due to that square planar chelates show greater interaction with nonpolar stationary phase than octahedral chelates. The results of van't Hoff plots have shown that platinoid metal acetylacetonates is operated on the same retention mechanism in the temperature range of $25{\sim}45^{\circ}C$. The study of the retention mechanism by the enthalpy-entropy compensation phenomenon has indicated that the retention mechanism of octahedral chelates and square planar chelates do not vary with the composition change of methanol-water mobile phase, respectively. In acetonitrile-water mobile phase, however, the retention mechanism is observed to be more complicated. Optimum condition for the separation of four platinoid metal acetylacetonates is found to be 40% methanol, polymeric C18 column, and $45^{\circ}C$.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.4
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• pp.433-453
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• 1999

There are a lot of elements affecting the success of implant prosthesis. The quality of surgical procedure is considered as one of the key factors. To avoid the excess heat generation is an important element of successful osseointegration and it can be achieved by using a gentle surgical technique with a sharp instrument in bone drilling. This study was performed to measure and analyze comparatively the heat transmitted to sur-rounding bone at a distance of 0.5mm from the periphery of the drill hole in each drilling stage. The results were as follows. In standard system, the temperature of surrounding bone tissue ranged from $29.2^{\circ}C\;to\;48.3^{\circ}C$ with irrigation and from $34.6^{\circ}C\;to\;84.3^{\circ}C$ without irrigation. And in wide system, the temperature of surrounding bone tissue ranged from $29.5^{\circ}C\;to\;52.5^{\circ}C$ with irrigation and from $34.8^{\circ}C\;to\;87.8^{\circ}C$ without irrigation. And the temperature ranges exceeded the threshold without irrigation, while showing less than the threshold by the cooling effect of irrigation. In comparing standard system with wide system, although there was no significant difference, ${\phi}4.3mm$ pilot and ${\phi}4.3mm$ twist drill of wide system showed high value and wide system showed slightly high elevation of temperature in all depth in fixture installation. In the finite element analysis, the calculated value by the Fourier's cooling law were applied to the bone drilling surface. And through analysis using different irrigation temperatures at $28^{\circ}C,\;15^{\circ}C\;and\;5^{\circ}C$, and according to the time. The result was that the cooling water at least below $15^{\circ}C$ was required to maintain the temperature of surrounding bone less than threshold in bone drilling, the cooling water below $5^{\circ}C$ was required to gain more sufficient cooling effect, and cooling over 5 seconds was needed after bone drilling for sufficient effect.

• Journal of The Korean Association For Science Education
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• v.38 no.5
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• pp.721-738
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• 2018

Nature of Science(NOS) has been a well-organized focus of science education and one of the key elements in defining and cultivating scientific literacy for more than a century. In recent years, a specific description of NOS, which is often known as 'the consensus view of NOS', has become very influential and has gained ready acceptance as an arrangement for both curriculum building and research into understanding of NOS by students and teachers in many countries around the world. This study has two purposes; one is to review some debates and criticism on the consensus view of NOS which consists of a list of sentences to describe nature of refined and general science, which have been heated up for the last few years by many prominent science education researchers, and the other is to consider alternative perspectives on NOS for the purpose of a new direction of NOS education. As a result of an investigation into such views as 'Teaching about NOS', 'Critical NOS', 'Critical Thinking-NOS', 'Whole Science', 'Features of Science' and 'Reconceptualized Family Resemblance Approach to NOS', some implications which focus on the generality and plurality of content knowledge of NOS based on current philosophy of science and sociology of scientific knowledge are suggested for the improvement of teaching and learning NOS.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.65-65
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• 2012

Copper zinc tin sulfide ($Cu_2ZnSnS_4$, CZTS) is a very promising material as a low cost absorber alternative to other chalcopyrite-type semiconductors based on Ga or In because of the abundant and economical elements. In addition, CZTS has a band-gap energy of 1.4~1.5eV and large absorption coefficient over ${\sim}10^4cm^{-1}$, which is similar to those of $Cu(In,Ga)Se_2$(CIGS) regarded as one of the most successful absorber materials for high efficient solar cell. Most previous works on the fabrication of CZTS thin films were based on the vacuum deposition such as thermal evaporation and RF magnetron sputtering. Although the vacuum deposition has been widely adopted, it is quite expensive and complicated. In this regard, the solution processes such as sol-gel method, nanocrystal dispersion and hybrid slurry method have been developed for easy and cost-effective fabrication of CZTS film. Among these methods, the hybrid slurry method is favorable to make high crystalline and dense absorber layer. However, this method has the demerit using the toxic and explosive hydrazine solvent, which has severe limitation for common use. With these considerations, it is highly desirable to develop a robust, easily scalable and relatively safe solution-based process for the fabrication of a high quality CZTS absorber layer. Here, we demonstrate the fabrication of a high quality CZTS absorber layer with a thickness of 1.5~2.0 ${\mu}m$ and micrometer-scaled grains using two different non-vacuum approaches. The first solution-processing approach includes air-stable non-toxic solvent-based inks in which the commercially available precursor nanoparticles are dispersed in ethanol. Our readily achievable air-stable precursor ink, without the involvement of complex particle synthesis, high toxic solvents, or organic additives, facilitates a convenient method to fabricate a high quality CZTS absorber layer with uniform surface composition and across the film depth when annealed at $530^{\circ}C$. The conversion efficiency and fill factor for the non-toxic ink based solar cells are 5.14% and 52.8%, respectively. The other method is based on the nanocrystal dispersions that are a key ingredient in the deposition of thermally annealed absorber layers. We report a facile synthetic method to produce phase-pure CZTS nanocrystals capped with less toxic and more easily removable ligands. The resulting CZTS nanoparticle dispersion enables us to fabricate uniform, crack-free absorber layer onto Mo-coated soda-lime glass at $500^{\circ}C$, which exhibits a robust and reproducible photovoltaic response. Our simple and less-toxic approach for the fabrication of CZTS layer, reported here, will be the first step in realizing the low-cost solution-processed CZTS solar cell with high efficiency.

• Journal of Life Science
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• v.24 no.3
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• pp.323-328
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• 2014

MicroRNAs comprise a family of small noncoding RNAs that modulate physiological processes, including adipogenesis. MicroRNA-17 (miR-17) promotes adipocyte differentiation and enhances lipid accumulation. The transcriptional regulation of miR-17 during adipogenesis remains unknown. In this study, we investigated whether miR-17 is a target of peroxisome proliferator-activated receptor ${\gamma}$ ($PPAR{\gamma}$), which is a key regulator of adipogenesis. The levels of miR-17 and the expression of $PPAR{\gamma}$ increased after the induction of adipocyte differentiation. Three putative peroxisome proliferator response elements (PPREs) were identified in the miR-17 promoter region. Using chromatin immunoprecipitation and luciferase reporter assays, we observed the interaction of $PPAR{\gamma}$ with the miR-17 promoter. Mutagenesis experiments showed that the -677/-655 region of the miR-17 promoter could function as a PPRE site. These results suggest that $PPAR{\gamma}$ is essential for transcriptional activation of the miR-17 gene, thereby contributing to understanding the molecular mechanism of adipogenesis in adipocytes.

• Journal of the Korea Safety Management & Science
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• v.10 no.4
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• pp.297-307
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• 2008

At the spots of enterprises experiencing rapid environmental changes, necessity for ceaseless managemental innovation is raised. We can't deny that management quality is also a part of such managemental innovation. Introduction of management quality by an organization is different from introduction of other individual innovative techniques. Management quality is not one time project but complete historical change program to be pursued continuously. Furthermore, it must be understood as a strategic 'Quality Journey' looking for far future of an organization. Malcolm Baldrige Model has been increasingly used in Korea as a global standard for management quality. The model, however, has shown a number of limitations in application due to nonsystematic elements in the implementation process. The deployment process of the model should be detailed through a real world case study. In this research, we proposed a quality evaluation standard model which is suitable for the Korean public enterprise based on the Malcolm Baldrige Non-profit Criteria, and examined the model. A 7-Point Likert Scale was used based on the seven categories within the 2007 Malcolm Baldrige Non-profit Criteria: Leadership, Strategic Planning, Customer and Market Focus, Management Analysis and Knowledge Management, Workforce Focus, Process Management, and Results. Furthermore, we analysed the validity and causal relationship among the factors within the model. Through the above case study, following common factors for successful Malcolm Baldrige Model have been derived. The following is a summary of the results of this study. First, for Malcolm Baldrige Model management, needs powerful support Leadership. Second, for Malcolm Baldrige Model management, needs systematic Strategic Planning. Third, for Malcolm Baldrige Model management, needs the continuous Customer and Market Focus. Fourth, for Malcolm Baldrige Model management, needs systematic Measurement Analysis and Knowledge Management. Five, for Malcolm Baldrige Model management, needs systematic Workforce Focus. Six, for Malcolm Baldrige Model management, needs systematic Process Management. The finding are surely necessary factors to arrange the human resource management for upgraded management quality, those factors help to explain why all enterprises consider human resource as the strategic view.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.31-37
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• 2014

In situ investigations and laboratory tests using elastic wave have become popular in geotechnical and geoenvironmental engineering. Propagation velocity of elastic wave is the key index to evaluate the ground characteristics. To evaluate this, various methods were used in both time domain and frequency domain. In time domain, the travel time can be found from the two points that have the same phase such as peaks or first rises. Cross-correlation can also be used in time domain by evaluating the time shift amount that makes the product of signals of input and received waveforms maximum. In frequency domain, wave propagation velocity can be evaluated by computing the phase differences between the source and received waves. In this study, wave propagation velocity evaluated by the methods listed above were compared. Bender element tests were conducted on the specimens cut from the undisturbed hand-cut block samples obtained from Block 37 excavation site in Chicago, IL, US. The evaluation methods in time domain provides relatively wide range of wave propagation velocities due to the noise in signals and the sampling frequency of data logger. Frequency domain approach provides relatively accurate wave propagation velocities and is irrelevant to the sampling frequency of data logger.

• Strategy21
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• s.46
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• pp.123-157
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• 2020

This research focuses on one important type of non-traditional threat, maritime piracy, and tries to supplement previous research from the perspective of military power, especially naval power. When considering the elements of military power, naval power is a core independent variable to explain piracy incidents. Indeed, naval power can play a key role in solving piracy problems, since naval power is the only legitimate force to respond to piracy in the sea. It is natural that well equipped and trained naval power in the sea increases the probability of capturing pirates, which leads to increasing the costs of piracy and decreasing its occurrences. In addition, since naval combatant ships have more impressive weapons than those of pirate boats, just the presence of naval combatant ships could serve to deter piracy incidents in the sea. The main purpose of this research is finding the effectiveness of large multinational naval efforts to deter piracy incidents in Africa. With this research purpose, I analyze 771 piracy incidents that occurred in African states from 2009 to 2014. Furthermore, I include all 33 coastal states in Africa regardless of the experiences of piracy incidents in order to avoid selection bias, which is very common in quantitative-based piracy incidents research. The dependent variable of this research is frequency of maritime piracy incidents for a country-year and the independent variable is the number of multi-national naval warships that operate near Somalia. With this analysis, I find the large number of multi-state naval combatant ships are negatively related to piracy incidents. In other words, as a main means to counteract piracy incidents, multi-state naval combatant ships are conducive to reduce piracy incidents near Somalia, since it increases costs (being captured) of conducting piracy.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.26-36
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• 2014

The needs of active phased arrays antenna system is getting more increased for IMT-Advanced system efficiency. The active phased array structure consists of lots of small transceivers and radiation elements to increase system efficiency. The minimized module of high efficiency transceiver is key for system implementation. The power amplifier of transmitter decides efficiency of base-station. In this paper, we design and implement minimized module of high efficiency transceiver for IMT-Advanced active phased array system. The temperature compensation circuit of transceiver reduces gain error and the analog pre-distorter of linearizer reduces implemented size. For minimal size and high efficiency, the implented power amplifier consist of GaN MMIC Doherty structure. The size of implemented module is $40mm{\times}90mm{\times}50mm$ and output power is 47.65 dBm at LTE band 7. The efficiency of power amplifier is 40.7% efficiency and ACLR compensation of linearizer is above 12dB at operating power level, 37dBm. The noise figure of transceiver is under 1.28 dB and amplitude error and phase error on 6 bit control is 0.38 dB and 2.77 degree respectively.