• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.21-35
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• 1997

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-20Pd-20Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electic furace and centrifugal casting machine in Ar atmoshpere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age-hardening characteristics of the small Au-containing Ag-pPd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, emergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, I. e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the Llo type face centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affedted by the Cu concentration. In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase(L1o type) and an Agrich ${\alpha}2$ phase occurred and a discontiunous precipitation occurred at the grain boundary. Form the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}\to{\alpha}+{\alpha}2+PdCu\to{\alpha}1+{\alpha}2+PdCu$ at Pd/Cu = 1 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Journal of Environmental Policy
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• v.8 no.4
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• pp.125-147
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• 2009

The Basic Environmental Policy Act (BEPA) (Law No. 4257 effective 1. August 1990) sets forth the basic policies and administrative framework for environmental preservation, leaving more detailed regulations, and emission controls to separate laws targeting air, water, and solid waste, etc. The BEPA Article 31 adopts an unprecedented strict liability standard for damages as an absolute liability. The BEPA Article 31 provides for liability as follows. If a company is alleged to have caused damage through pollution of the environment, it will be liable for damages unless it can show that the pollution did not cause damages, or that it did not actually cause pollution. If the company did cause pollution, and if the pollution is the cause for the damages in question, the company will be liable irrespective of whether it was negligent or otherwise at fault. If there are two or more companies involved in the pollution, but it is unclear which company caused the damages, all of the companies will be jointly and severally liable for the damages. In this paper, the author attempts to uncover the problems of BEPA Article 31 and then seeks desirable amendments by comparing it to the German Environmental Liability Act. First, it will be necessary to provide definitions of 'companies etc.'. Second, it will be necessary to enumerate the kinds of company facilities. Third, it will be necessary to provide exclusionary clauses on material damages. Fourth, it will be necessary to show 'presumption of cause and effect'. Fifth, it will be necessary to provide a clause on 'right to information'. Sixth, it will be necessary to provide a clause for force majeure. Seventh, it will be necessary to take measures to secure abundant liability for damages which can be caused by the owner of the facility, the potential polluter. Finally, it is appropriate that Korea now legislate an Environmental Liability Act akin to the German Environmental Liability Act.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.137-147
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• 2001

Acidic primer is the bonding agent which combines the conditioning and priming agent into the single solution and was originally developed for the dentin bonding system. It is less harmful to the tooth structure and more convenient to manipulate than the traditional etching procedure. The Purpose of this study is to evaluate the shear bond strength of various bonding materials when the enamel is treated with acidic primer for the bracket bonding procedure. Fifty recently extracted human premolars were randomly separated into five groups -Group I using Clearfil Liner Bond 2 adhesive system to the enamel treated with acidic primer, Group II using Transbond XT adhesive system to the enamel treated with acidic primer, Group III using panavia 21 adhesive system to the enamel treated with acidic primer, Group IV using Fuji-Ortho LC adhesive system to the enamel treated with acidic primer, Group V using Transbond XT adhesive system to the enamel treated with 37$\%$ phosphoric acid. The shear bond strength was measured with Instron universal testing machine after storing in $37^{\circ}C$ water bath for 48 hours. After debonding, the teeth and brackets were examined under scanning electron microscope (SEM) and assessed with the adhesive remnant index (ARI). The results were as follows : 1. There were no significant differences in shear bond strength between group III ($8.69{\pm}2.72MPa$), group IV (9.7 ± 3.16 MPa), and group V ($10.48{\pm}2.60MPa$) (p>0.05). 2. The shear bond strength of group III and group IV was significantly higher than that of group I ($1.09{\pm}0.53MPa$), and Group II ($2.70{\pm}1.46MPa$) (p<0.05). 3. The ARI of group IV ($2.1{\pm}1.1$) and group V ($2.9{\pm}0.3$) was significantly higher than that of group I ($0.2{\pm}0.4$), group II ($0.3{\pm}0.9$) and group III ($0.2{\pm}0.4$) (p<0.05). 4. There were no significant difference between the ARI of group IV and group V (p>0.05). This result suggests that the combination of acidic primer and some bonding adhesive can provide sufficient shear bond strength for clinical orthodontics.

• Journal of Oral Medicine and Pain
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• v.30 no.2
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• pp.269-276
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• 2005

This in vitro study evaluated the influence of a flowable composite resin on the tensile bond strength of resin to enamel and dentin treated with Er:YAG laser and diamond bur. 96 Buccal enamel and mid-coronal dentin were laser-irradiated using an Er:YAG laser and treated with diamond bur. Each groups(48) were divided two small groups depends on acid-etching procedure. Light-cure flowable resin(Metafil Flo) and self-cure resin(Clearfil FII New Bond) were used in this study. After surface etching with 37% phosphoric acid and the application of an adhesive system, specimens were prepared with a hybrid composite resin. After 24hours storage in distilled water at 37$^{\circ}C$, all samples were submitted to the tensile bond strength evaluation, using a universal testing machine(Z020, Zwick, Germany). The obtained results were as follows: 1. TBS of acid-etching group were higher than those of non-etching group in both enamel and dentin treated with Er:YAG laser and diamond bur. Laser 'conditioning' was clearly less effective than acid-etching. Moreover, acid etching lased enamel and dentin significantly improved the microTBS of M-Flo. 2. In enamel, TBS of laser-irradiated group were lower than those of bur-prepared group. However, in flowable resin subgroup, there were not differed those between two groups in dentin. 3. In laser-treated group, TBS of flowable composite resin were higher than those of self-curing resin in dentin, however, there was no difference in enamel. From this study, we can conclude that the self- and light-cure composite resin bonded significantly less effective to lased than to bur-cut enamel and dentin, and that acid-etch procedure remains mandatory even after laser ablation. We suggest that Er:YAG laser was useful for preparing dentin cavity with flowable resin filling.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.11
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• pp.1571-1579
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• 2009

Antioxidant activities of ethanol and water extracts from Orostachys japonicus leaf, stem, and root were determined by rancimat method, DPPH radical scavenging effect, chelating effect, and reducing power analysis. The highest total phenolic compound (TPC) as 14.6 mg/g of dry sample and the strongest antioxidant activity in rancimat method (value of AI 1.98), DPPH radical scavenging effect (96% in 4 mg/mL), and reducing power (1.50 in 4 mg/mL) were observed in ethanol extracts from Orostachys japonicus leaf. Heat and pH stabilities on antioxidant activity of Orostachys japonicus leaf extract were studied through TPC and DPPH radical scavenging effect. As a result, the extracts from Orostachys japonicus leaf showed high stability. These results suggest that extracts from Orostachys japonicus leaf can be potentially used as proper natural antioxidant in the food industry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.11
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• pp.1535-1542
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• 2009

To find the new use of Korean ginseng and mushroom, crude polysaccharides were prepared from submerged cultures of Hericium erinaceum in the medium supplemented with Korean ginseng extracts. When we fractionated crude polysaccharides (HE-GE-CP-1, 3, and 5) from hot-water extracts of submerged cultures of H. erinaceum with ginseng extracts (1%, 3%, and 5% addition of total medium), the yields of HE-GE-CP-1, 3, and 5 were identified at 5.7, 5.1, and 4.8%, respectively. Among crude polysaccharide fractions, HE-GE-CP-5 was significantly higher (1.89-fold of the saline control) than those of HE-GE-CP-1 (1.64-fold) or HE-GE-CP-3 (1.76-fold) on mitogenic activity of splenocytes. HE-GE-CP-5 also had the more potent bone marrow cell proliferation (1.83-fold) rather than HE-CP or HE-GE-CP-1 or HE-GE-CP-3 (1.59- or 1.44- or 1.69-fold, respectively), and anti-metastatic activity as anti-cancer effect showed the highest prophylactic value (72.4% inhibition of tumor control) in 5% supplementation of ginseng extract. However, the lysosomal phosphatase of macrophage was significantly stimulated after HE-GE-CP-3 treatment (2.03-fold). In addition, the immunostimulating and anti-metastatic crude polysaccharide, HE-GE-CP-5, contained mainly neutral sugars (63.2%) with considerable amounts of uronic acid (19.3%) and a small amount of proteins (8.8%). HE-GE-CP-5 can stimulate immune system to inhibit tumor metastasis, and its anti-tumor metastasis may be associated with macrophages, splenocytes and Peyer's patch cells activation.

• Journal of Korean Society of Forest Science
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• v.109 no.3
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• pp.259-270
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• 2020

Extreme weather events, such as heat and drought, have occurred frequently over the past two decades. This has led to continuous reports of cases of forest damage due to physiological stress, not pest damage. In 2014, pine trees were collectively damaged in the forest genetic resources reserve of Sogwang-ri, Uljin, South Korea. An investigation was launched to determine the causes of the dieback, so that a forest management plan could be prepared to deal with the current dieback, and to prevent future damage. This study aimedto 1) understand the topographic and structural characteristics of the area which experienced pine tree dieback, 2) identify the main causes of the dieback, and 3) predict future risk areas through the use of machine-learning techniques. A model for identifying risk areas was developed using 14 explanatory variables, including location, elevation, slope, and age class. When three machine-learning techniques-Decision Tree, Random Forest (RF), and Support Vector Machine (SVM) were applied to the model, RF and SVM showed higher predictability scores, with accuracies over 93%. Our analysis of the variable set showed that the topographical areas most vulnerable to pine dieback were those with high altitudes, high daily solar radiation, and limited water availability. We also found that, when it came to forest stand characteristics, pine trees with high vertical stand densities (5-15 m high) and higher age classes experienced a higher risk of dieback. The RF and SVM models predicted that 9.5% or 115 ha of the Geumgang Pine Forest are at high risk for pine dieback. Our study suggests the need for further investigation into the vulnerable areas of the Geumgang Pine Forest, and also for climate change adaptive forest management steps to protect those areas which remain undamaged.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.1
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• pp.47-54
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• 2014

The aim of this study is to evaluate the effects of green tea polyphenol (GTP) on anticancer treatment with cisplatin (CP), using both an in vitro cell culture model and an in vivo mouse model of established breast tumor. Mouse breast cancer cells (EMT6) were treated with or without GTP and CP followed by determination of the cell viability using an MTT assay. The relative cell viability of CP treated EMT6 cells was 96% at a 20 ${\mu}g/mL$ concentration of cisplatin; however, in combination with GTP (50 ${\mu}g/mL$), the cell viability decreased to 20% at the same concentration of CP (20 ${\mu}g/mL$). For the in vivo study, EMT6 cells were inoculated into Balb/c mice for the establishment of a tumor-bearing mice model. The tumor-bearing mice were treated with CP (5 mg/kg. i.p.) with or without dietary GTP (0.2% drinking water). Tumor growth was monitored by a measurement of tumor size using a digital caliper, and nephrotoxicity was determined by enzymatic and histological examinations. The levels of p53 and caspase-3 in tumor tissues were examined by a Western blot. In tumor-bearing mice treated with GTP plus CP, the increment of tumor volume showed a significant reduction, compared with CP or GTP alone. The levels of p53 and cleaved caspase-3 (caspase-3/p17) in tumor tissues of tumor-bearing mice were increased by CP and GTP compared to CP alone. In CP treated tumor-bearing mice, ${\gamma}$-glutamyltranspeptidase (GGT) and alkaline phosphatase (AP) activities were decreased, and marked tubular necrosis and dilatation were observed in the kidney. CP-induced enzymatic and histopathological changes in the kidney of tumor-bearing mice were reduced by combinations of GTP with CP. The results of these experiments demonstrated that dietary GTP has a potentiating effect on CP anti-tumor activity and a protective effect against CP-induced renal dysfunction. Therefore, GTP may be used as a modulator in anticancer treatment with CP.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1197-1206
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• 2014

This study compared and analyzed the physiochemical and quality characteristics of young radish kimchi made with YR-FNC or YR-GC cultivated by organic farming as well as kimchi made with young radish cultivated by chemical composting/general farming (YR-Control). YR-Control showed higher contents of water and crude protein than YR-FNC and YR-GC kimchi but lower contents of crude ash, dietary fiber, and vitamin C. YR-FNC and YR-GC kimchi also showed higher contents of P and Cu than YR-Control but lower contents of N, K, Ca, Mg, Fe, and Zn. YR-Control fermentation progressed faster than that of YR-FNC or YR-GC after 24 days, and YR-Control more rapidly reached an appropriate pH. On the other hand, YR-FNC and YR-GC kimchi fermentation progressed slow and did not reach a pH level below 5.3. For period of fermentation, YR-Control and YR-FNC kimchi showed no significant difference in reducing sugar content, whereas that of YR-GC kimchi decreased significantly after 24 days of fermentation (P<0.002). YR-FNC and YR-GC kimchi showed 1.5~3 times higher total polyphenol and flavonoid contents than YR-Control at the beginning of fermentation, whereas YR-Control and YR-FNC kimchi showed a significant increase in total polyphenol and flavonoid contents during the fermentation period. By day 7 of fermentation, YR-FNC kimchi showed higher contents of lactic acid bacteria and total microbes than YR-Control. In the sensory evaluation, YR-FNC and YR-GC kimchi showed higher preference values than YR-Control. Therefore, kimchi made from young radish cultivated by organic farming has a longer freshness period than control kimchi and is characterized by excellent sensory quality, increased physiological contents, and improved beneficial health effects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1270-1277
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• 2014

This study investigated the quality characteristics of instant rice noodles manufactured with broken rice flour as an application of rice-processed products. We examined the physicochemical characteristics of common rice flour (CRF), broken rice flour (BRF), and CRF mixed with BRF (CBRF). Futhermore, instant rice noodles were manufactured with these three types of rice flour, and their quality and sensory characteristics were also investigated. Damaged starch content and water-binding capacity of rice flour were highest in BRF. Particle size of rice flour was significantly different among the three types. RVA pasting viscosities of BRF and CBRF were higher than that of CRF. Volume after cooking of instant rice noodles increased in rice noodles made with broken rice flour (BRN). Turbidity and cooking loss of BRN were higher than those of common rice noodles (CON). For texture properties, CON displayed the highest hardness, adhesiveness, and chewiness. In the sensory evaluation, springiness and overall acceptability values of CON were significantly higher than those of other rice noodle types (BRN and CBRN). In conclusion, BRN showed increased cooking loss and turbidity with reduced texture and overall acceptability values. The results of this study suggest that added amount of CRF may significantly increase the overall quality of instant rice noodles prepared with BRF.