• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.27-33
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• 2009

In this study, it was analysed physical characteristics, TS, moisture, C/N ratio, leaching test, and element analysis in landfill wastes of 10 years old without landfill pretreatment. The Organic material content was 7.2%~23.5% and soil was the main inorganic materials which it's rate was 54.1%~71.0%, in landfill wastes. The results of TS, VS, and moisture were represented 51.5%~68.1%, 23.6%~56.1%, 32.0%~48.4%, respectively. The analysis of hazardous materials did not indicate Hg, $Cr^{+6}$, CN, Organic Phosphorus, TCE and PCE, however the Pb of leaching materials showed 0.023~0.092 mg/L, which was the highest. As the result of the element analysis, C was 47.74%~56.72%, N was 4.09%~9.92%, the C/N ratio was 5.76~12.57 and the result of soils around landfill was the highest heavy material, Pb, 2.465 mg/kg~10.251 mg/kg. The objectives of this paper are to investigate states, stabilization of these closed landfills and to gain suitable data for post-closure care using some parameters through analysis of landfill environment.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.611-620
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• 2007

Statement of problem: Second-generation indirect composite resins have been improved flexural strength, compressive strength, hydrolytic degradation resistance, wear resistance compared to first-generation indirect composite resins, but there are still some problems as hydrolysis and low wear resistance. Some manufacturers claim that wear resistance of their materials has been improved, but little independent study has been published on wear properties of these materials and the properties specified in the advertising materials are largely derived from in-house or contracted testing. Purpose: This study was to evaluate the wear of indirect composite resins (SR Adore, Sinfony, Tescera ATL) and gold alloy against the human enamel. Material and method: Extracted human incisors and premolars were sectioned to $2{\times}2{\times}2mm$ cube and embedded in the clear resin and formed conical shaped antagonist to fit the jig of pin-on-disk tribometer. Total 20 antagonists were stored in distilled water. Five disk samples, 24mm in diameter and 1.5mm thick, were made for each of three groups of indirect composite resins and gold alloy group, and polished to #2,000 SiC paper on auto-polishing machine. Disk specimens were tested for wear against enamel antagonists. Wear test were conducted in distilled water using a pin-on-disk tribometer under condition (sliding speed 200rpm contact load 24N, sliding distance 160m). The wear of the enamel was determined by weighing the enamel antagonist before and after test, and the weight was converted to volumes by average density. The wear tracks were analyzed by scanning electron microscopy and surface profilometer to elucidate the wear mechanisms. Statistical analysis of the enamel wear volume, wear track depth and wear tract width of disk specimens were accomplished with one-way ANOVA and the means were compared for significant differences with Scheffe's test. Results: 1. The enamel wear was most in gold alloy, but there were no statistically significant differences among all the groups (P>.05). 2. In indirect composite resin groups, the group to make the most shallow depth of wear tract was Sinfony, followed by Tescera ATL, SR Adoro (P<.05). Gold alloy was shallower than Sinfony, but there was no statistically significant difference between Sinfony and gold alloy (P>.05). 3. The width of wear tract of SR Adore was larger than the other groups (P<.05), and there were no statistically significant differences among the other groups (P>.05). 4. SEM analysis revealed that Sinfony and gold alloy showed less wear scars after test, Tescera ATL showed more wear scars and SR Adore showed the most. Conclusion: Within the limits of this study, Sinfony and gold alloy showed the least wear rates and showed similar wear patterns.

• Journal of Adhesion and Interface
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• v.5 no.1
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• pp.3-11
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• 2004

In this work, the cure behaviors of the DGEBA/PMR-15 blends initiated by N-benzylpyrazinium hexafluoroantimonate (BPH) as a cationic latent catalyst were performed in DSC and DMA analyses. And, the thermal stabilities were carried out by TGA analysis and their mechanical interfacial properties of blends were measured in the context of critical stress intensity factor ($K_{IC}$). As a result, the curing activation energy ($E_a$) determined from Ozawa's equation in DSC and the relaxation activation energy ($E_r$) from DMA were increased with increasing PMA-15 content. Also, the thermal stabilities obtained from the integral procedural decomposition temperature (IPDT) and the glass transition temperature ($T_g$) were highly improved with increasing the PMR-15 content, which were probably due to the high heat resistance. And, the $K_{IC}$ showed a similar behavior with $E_a$, which was attributed to the improving of the interfacial adhesion or hydrogen bondings between intermolecular chains.

• 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.

• The Research Journal of the Costume Culture
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• v.7 no.5
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• pp.33-45
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• 1999

Examine the dress which the Emperor actually wore in Gun-ryung 42nd year of Ching dynasty, comparison of 《Cheong-hoi-jeon-do》 with the Emperors year-round dress in Gun-ryung the 41st year was made and summarize the result as follows. It was used almost similar to the code of 《Cheong-hoi-jeon-do》. Though the materials and colors were more diverse than those of the previous year, it seems that actual use of material was plain under the influence of mourning. All the materials for summer hat were rattans. And velvet was the material for the patrol hat, but actually used before they change to summer material after fur use was over according to the season, which can be said as more reasonable use than the code. Materials of coat were more diverse than the precious year and also they put on ko-hemp cloth which was not found in the previous year. This can be understood that they expressed their guilt-consciousness to the dead as dress material by wearing ko-hemp cloth during the summer after periiod of mourning was over. And they put on the ko-hemp, the Emperors ordinary dress, much longer time than the previous year and this seems to be coherent to the meaning of wearing ko-hemp cloth. They followed the Emperor\`s Jo-bok1 one for the Kae-bok which were not systematized and Jae-dae used Jo-dae2 as the Emperor\`s Jae-bok in 42nd year. This was the same as the Jae-bok code of the previous year. Jo-ju did not follow the code of 《Cheong-hoi-jeon-do》, but made a wide variety. For the belt, the same as 41st year, it marked the gem decoration style on the Jae-bok belt as a square type and mourning dress by using the round type. The Emperors dress in 41nd year showed one side of the patrol clothes by the patrol of San-dong. On the contrary, it was also the chance to see one side of funeral garments in 42nd year. In Gun-ryung 42nd year, the Emperor put on the funeral garments for hundred days. Accordingly even in parts, we can see that the Emperor wore two kinds of dress for hundred days, that is, color dress and white dress and white dress. While on duty, in other words, everyday dress was only blue color and also the same color for the belt and shoes. But didn\`t put on Jo-ju. When they were in mourning, they wore white dress and belt as a funeral garments, which were called Hyo-bok, Hyo-bok.

• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.65-77
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• 2011

Purpose: The purposes of this study were to provide information about safe actions during the practice of dental technology, promote belief in safe actions among the students of dental technology, and reinforce their knowledge about how to act safety. Methods: Open questions were asked to 120 sophomores majoring dental technology to understand the target group's belief about safe actions. Following the instructions by Ajzen & Fishbein, the collected data were grouped according to similar beliefs. Those beliefs of the highest frequency were given a priority and got to represent the belief level of the target group. Even with belief changes, however, they would not be able to practice safe actions if they had no knowledge about how to do safe actions. For desirable behavioral changes among the students, the students were then asked to discuss the current state of safety accidents and issues focusing on the materials and processes used in the practice and give presentations regarding the subjects to identify risk factors. Then the identified risk factors were used to devise the program contents so that the students could practice safe actions through accurate behavioral approaches and belief changes by educating them about how to act safely by the practice processes and the involved materials and devices. Results: Not only do the students of Dept. of Dental Technicians have difficulties with the complex practice processes while practicing to make dental prosthesis, but they are exposed to the risk of accidents as they're poor at dealing with the materials and devices. Although there is a definite need for accident prevention education programs before practice, the reality is that the school doesn't the schoosuch education. Based on the judgment that an education program designed to reinforce belief for behavioral changes would generate effgrams results, an education program was developed by applying the Theory of Planned Behavior(TPB). Along with their beliefs, the current state of accidents n. Basepractice, demand for safety education, and practice level of safe actions were used to device the contents of accident prevention education and to develop an accident prevention education program for dental technology. Conclusion: The study presents an accident prevention education program developed to reinforce dental technology students' beliefs and knowledge and to help them do safe actions during practice.

• Journal of Periodontal and Implant Science
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• v.26 no.2
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• pp.334-349
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• 1996

Regeneration of the periodontal tissue destroyed by periodontal disease is one of the final goals of periodontal therapy. In the past few years, periodontists have used various alloplastic grafting materials in an attempt to regenerate bone lost from periodontal disease. These materials have used widely because they have shown to be nontoxic, biologically compatible with surrounding host tissue and chemically similar to bone. The purpose of this study was to investigate the effect of Porous Resorbable Calcium Carbonate and Porous Replamineform Hydroxyapatite on the regeneration of the alveolar bone and the healing of roots transplanted into the periodontally diseased extraction sockets of dogs. The experimental chronic periodontitis was induced by elastic ligatures on the 2nd and 3rd mandibular premolars of 2 adult dogs for 8weeks after surgically creating periodontal defect. The extracted root were split in half along the long-axis, and the extend of plaque exposure was marked on the root surfaces with burs. The roots were inserted in extraction sockets with Porous Resorbable Calcium Carbonate(PRCC) in left side and with Porous Replaminefrom Hydroxyapatite(PRH) in right side. The flaps were sutured to cover the sockets completely. The animals were sacrificed after 12 weeks of healing, and the specimens were examined histologically. The results were as follows: 1. No inflammatory reactions were observed in either groups. 2. Hoot resorption was observed in both groups while the general outline of the roots were maintained. 3. PRCC was almost completely resorbed and replaced with new bone, while R.H.A. was not resorbed & remained encased in newly-formed C-T and alveolar bone. 4. PRH was encapsulated with alveolar bone which has been deposited from apical & lateral area of the sockets, while the coronal portion of the sockets were filled with C-T. 5. In both groups, the resorbed portions of the roots were replaced with new bone. These results suggest that either PRCC or PRH may not interfere with bone formation or healing in extraction sockets, and in some degree, retard the root resorption. Because the roots maintained in anatomy, we think that graft materials prevent the root resorption.

• Journal of East-West Nursing Research
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• v.2 no.1
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• pp.37-53
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• 1997

The purpose is to inspect the personal medicines in Cheju island that are used traditionally and to get their characteristics. The subjectives are 39 Cheju people, men 10, women 29, who were horned, grown up in Cheju and agreed with this study. The ranges of age are 10 persons(m : 1, w: 9) over 40 less 50 years old, 14(m : 7, w : 7) over 50 less 60, 5(m : 1, w : 4) over 60 less 70, 6(m : 0, w : 6) over 70 less 80, and 4(m : 1, w : 3) over 80. The average age is 64.5 years old. The method to collect the data is 20 structured opening questionaires that are based on references. The duration to collect datas is 11days from 4th, Aprill 1997 to 14th, Aprill 1997. The workers who are trainned the interview methods went their villages and got answers after explaining the purpose and contents to them. Somtimes they used to record the answers. The analysis was identified the subjectives to four regions of Cheju, arranged answers with items, rearranged the same answers, counted with number and percentage. And classified the materials and characteristics. The results of this study are followed: The things that is used as personal medicines are the effects through experiences ans misteries that have hand down by word of mouth, even though they are not scientific. People used the materials arround their circumference. It is an accumulation of experiences. The ways used in eating, doing acupuncture or sting, exposing to smoke, wheedling, fixing after pounding. Almost materials are plants. Mugwort is effective in fever, gastritis, hemorrhoid, diarrhea, edematous hands or feet and dermatitis. Citron and Arrowroot in fever, gastritis. Seeds of Pumpkin in indigestive, hemorrhoid, edematous hands or feet. Gallic in fever, diarrhea, frostbite, dermatitis, and toothache. Motherwort in diarrhea, gastritis. Radish juice in indigestive, jaundice. Bean paste in burn, wound. Acupuncture in fever, gastritis, indigestive, back pain, edematous hands or feet. Sting as similar with it in fever, indigestive, edematous hands or feet. Cigarrette in hemorrhoid, wound, toothache. Cowstools in edematous hands or feet, wound. Sault is usded a lot in fever, gastritis, indigestive, hemorrhoid, uneffective voiding, edematous hands or feet, dermatitis, having a boil around the mouth, toothache, and eye disease. Japanese Parsley in fever, gastritis. Egg Apple in diarrhea, edematous hands or feet, frostbite. And Wild Chrysanthemum is effective in jaundice. In the conclusion, people used the things arround. A things is effective in several symptoms. If these are not effective, they would used the magic as god's anger. As locally, they used the grasses and fruits in the middle of Mt. Halla and seafood on the sea village.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.234-248
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• 1998

The purpose of this study was to compare the fracture and shear bonding strength of resin-modified glass ionomer cements with composite resin and conventional glass ionomer cement Three kinds of restorative materials including a composite resin (Z 100), a conventional glass ionomer cement(Fuji II), and resin- modified glass ionomer cements(Fuji II LC, Vitremer, Dyract and Compoglass) were investigated in this study. For measurement of fracture and shear bonding strength, disk samples of the materials were prepared and cylindrical samples of the materials were bonded the flat enamel and dentin surfaces according to manufactuer's instructions. All specimen were determinated by using an Instron testing machine with a crosshead speed of 1 mm/min. Then, each treated enamel and dentin surface was observed by SEM. The following results were obtained. 1. The bi-axial flexural strength of Z 100 was highest, and Fuji n LC, Vitremer, Dyract and Compoglass were significantly higher than Fuji n (P<0.05). 2. The shear bonding strength of Z 100 on the enamel and dentin surface was higher than other experimental groups except Fuji II LC(P<0.05). Fuji II LC was significantly higher than Fuji II (P<0.05), but in the case of Vitremer, Dyract and Compoglass were similar to Fuji II (P>0.05). 3. The shear bonding strength of Z 100 and Fuji II LC on the enamel surface were highly increased as compared with dentin surface (P<0.05), but in the case of Fuji II, Vitremer, Dyract and Compoglass were not different between enamel and dentin(P>0.05). 4. In the Z 100 and Fuji II LC, obvious etched enamel surface and exposed dentinal tubules according to remove of smear layer and smear plug were observed.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.293-300
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• 2016

Purpose: The purpose of this study is finding proper bonding agents to be used when adding bis-acryl composite provisional materials. Materials and Methods: Three bonding agents with different chemical compositions were included in this study. Forty disk shaped specimens of bis-acryl composite provisional material were prepared and divided into 4 groups according to the bonding agents. Control group didn't have bonding agent. Through the Teflon mould with 4.0 mm diameter hole with 4.0 mm thickness the same bis-acryl composite provisional material was added on the disks after the surface of each specimen was treated with designated bonding agent according to the manufacturer's instructions. Shear bond test was performed and the fractured surfaces were inspected with a microscope. One-way analysis of variance was conducted and the result was further analysed with Turkey post hoc test at the significance level of 0.05. Results: The highest strength was acquired from the specimens bonded with chemical cure system and it was statistically significant (P < 0.05). This group showed 100% cohesive failures. The lowest bonding strength was recorded from the specimens used conventional light cure bonding agent, and this group's result was similar with the control group. The group used a light cure bonding agent claiming improved compatibility revealed significantly higher bond strength to the traditional light cure bonding agent group in a statistically significant way (P = 0.043). Conclusion: According to the bonding agent used the shear bond strength was significantly affected. Therefore the choice of proper bonding agent is important when hiring a bonding agent to add bis-acryl composite provisional materials.