• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.2
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• pp.158-164
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• 2019

The purpose of this study was to compare the bond strength of resin-modified glass ionomer (RMGI) to dentin with saliva contamination at different stages and using different decontamination procedures. Extracted human permanent molars were embedded onto acrylic resin with the dentin surface exposed. Group I was a control group that was conditioned with polyacrylic acid (PAA). Groups II and III were contaminated with saliva before PAA conditioning and Groups IV, V, and VI were contaminated with saliva after PAA conditioning. After saliva contamination, Groups II and IV were dried, Groups III and V were rinsed and dried, and Group VI was additionally conditioned with PAA. After surface treatment, the dentin specimens were filled with RMGI. Group I showed significantly higher bond strength than the other groups. Group VI showed a significantly higher bond strength than the other saliva contaminated groups. However, there were no significant differences in the failure mode between the different groups. Saliva contamination impaired the bond strength of RMGI to dentin, regardless of when the saliva contamination occurred. Decontamination with washing and drying could not improve the shear bond strength of RMGIC. When saliva contamination occurred after PAA conditioning, additional PAA conditioning improved the shear bond strength.

• Journal of the Korean Wood Science and Technology
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• v.49 no.6
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• pp.574-590
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• 2021

International efforts to prevent illegally logged wood are expanding around the world. The "Legal Wood Trade Promotion System" was enacted in Korea in 2019 to strengthen the legal import and distribution of commercial wood in Korea. Since then, this system has promoted and ensured that the imported wood and wood products are legal with respect to the country of origin, wood species, and harvested area. As verification methods, DNA analysis technology and anatomical analysis using a microscope are mainly used in conjunction. Therefore, in this study, wood species of plywood were identified by analyzing the anatomical characteristics of various wood products for the first time. Douglas fir (Pseudotsuga menziesii (Mirb.) Franco.) and larch (Larix kaempferi (Lamb.) Carriere) plywoods (7, 9 ply) were obtained from four companies that supply plywood in Korea. After cutting each company's plywood to a size of about 1 cm³, the layers from top to bottom were separated into single layers, and three sections were observed using an optical microscope. The results revealed that the plywood was composed of a mixture of softwood and hardwood wood species, pine wood species, poplar wood species, or a mixture of larch and pine wood species. Identification of wood species using microscopy is important and can enable the scientific analysis and verification of various wood products, including plywood, imported from countries where the likelihood of indiscriminate distribution of illegal wood and illegal logging is high.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.651-660
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• 2021

This study examined the trend of standards established in the United States and to find points that can be applied to Korean defense standards. The titles of various United States defense standard documents registered on the web were selected for this research. The wordcloud was created after analyzing the frequency of words appearing in the title using text mining. The trend of words appearing in MIL-STD by era was obtained. This study identified words that appear often due to the format of the document itself, words that appear regularly throughout the era, words that are used frequently in the past but are not used much in the present, and words that did not receive attention in the past but appeared recurrently in the present. In addition, the characteristics of each document were derived through the wordcloud produced for various defense documents. In conclusion, Korean defense standards also require a consideration of safe and efficient management, transport, and load design of hazardous materials. Furthermore, the quality of defense standards can be expected to improve if the defense standard document system can be established, focusing on efficient management.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.3
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• pp.103-111
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• 2021

Hexagonal shape Si crystals were grown by the mixed-source hydride vapor phase epitaxy (HVPE) method of mixing solid materials such as Si, Al and Ga. In the newly designed atmospheric pressure mixed-source HVPE method, nuclei are formed by the interaction between GaCl_n, AlCl_n and SiCl_n gases at a high temperature of 1200℃. In addition, it is designed to generate a precursor gas with a high partial pressure due to the rapid reaction of Si and HCl gas. The properties of hexagonal Si crystals were investigated through scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), high-resolution X-ray diffraction (HR-XRD), and Raman spectrum. From these results, it is expected to be applied as a new material in the Si industry.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.173-177
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• 2011

In this study, the formation of $AlPO_4$-type porous materials from alum sludge was investigated. The materials were synthesized by the reaction of aluminum hydroxide and phosphoric acid with an organic template. Cationic surfactant, natural humic acid, and amino acids were used for the organic template. The residual organic templates were removed by calcination at $600^{\circ}C$ in the air. Powder X-ray diffraction patterns showed the charicteristic patterns of the $AlPO_4$-type porous materials. The morphology of the material was examined using a scanning electron microscopy. The coordination environment of $Al^{3+}$ ion was investigated by $^{27}Al$ MAS NMR technique. Both tetrahedrally and octahedrally coordinated$Al^{3+}$ ions were found in the as-synthesized samples while all $Al^{3+}$ ions were tetrahedrally coordinated in the calcined products. The development of mesopore in the solid material was confirmed by the measurement of BET specific surface area. Finally, they were used for removal of toxic formaldehyde from the air and the formaldehyde molecules were adsorbed on the surface of pores. In conclusion, $AlPO_4$-type porous materials from alum sludge might be applicable in the removal of toxic volatile organic compounds from the air.

• Food Science and Industry
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• v.49 no.2
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• pp.25-33
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• 2016

우리나라의 발효식품 산업의 규모는 2010년 약 4조 원으로 식품 산업 전체의 4.0%정도이며, 이 중 전통 발효식품이 50.0% 수준으로 전체 식품 산업 대비 비중은 2.0%에 불과하지만, 발효제품의 세계 시장 규모는 2000년 152억 달러, 2010년 730억 달러로 급속한 성장으로 확대되고 있다. 국내 소금시장의 규모는 2010년 기준 1,300억 원이며, 전 세계적으로 나트륨 대체 염미제의 시장수요는 절실히 필요한 실정으로, 최근 2,000억 원대 규모를 유지하고 있는 간장 시장에서 염도를 낮춘 '저염 간장'매출 성장세를 보이고 있어 소금을 줄이는 식생활 개선에 대한 교육 홍보와 더불어 '나트륨 저감화 식품 개발의 필요성'이 국민건강증진, 경제성 측면에서 날로 커지고 있다. 또한, 2007년부터 웰빙 열풍으로 자연조미료 제품의 비중이 크게 늘어나는 추세이며, 100% 천연재료로 사용하여 소비자용 제품 출시 등 다양한 변화를 가져온 결과, 자연조미료 시장은 2008년 151억 3,200만 원의 매출규모에서 215억 2,600만원으로 무려 42.3%를 차지했으며, 저염을 위하여 활용하는 저염 소금도 연령대가 높아질수록 선호도가 높아지는 있다는 보고가 있다. 식품의약안전처의 '나트륨 저감화 사업'은 2012년부터 연차별로 가공식품의 나트륨 저감화 가이드라인을 개발하여 가공식품 생산업체들의 참여를 유도하며, 다양한 홍보를 펼쳐 2014년 6월 기준으로 165개 제품의 나트륨이 저감화 되었으며, 2015년에는 95종의 면류제품의 나트륨 함량이 약 20% 이상 저감되는 실적을 보여주었다. 여러 지역자체 단체들은 지역의 특성을 최대한 살려 다양한 발효산업 육성을 진행하고 있음에 영남권의 장류 업체를 대상으로 나트륨 섭취량을 줄일 수 있도록 '경북 발효식품 수출농업기술지원단'은 식품의약품안전처와 연계하여 지속적으로 가공식품 중 나트륨 저감화에 노력을 할 것이며 이에 대기업과 함께 중소기업들의 참여도를 높이기 위해 현장 컨설팅을 지역적으로 실시할 계획으로 각 지역별 업체들의 참여도를 높일 계획이다. 이를 통해 전통 발효식품이 기능성을 유지하면서 나트륨 함량을 줄인 건강식품으로 우리나라 식품산업 발전에 기여하고자 노력할 것이다. 향후 발효산업 중 한류의 매운맛, 김치 등을 시작으로 고성장이 기대되는 세계화 전략 품목이며 지역 농산물을 활용한 발효식품 세계화를 위하여 나트륨 저감화는 반드시 선행되어야 할 것으로 생각된다.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1315-1323
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• 2018

We studied the carbonization due to the annealing condition of waste coffee powder for application as an active anode material for lithium-ion batteries (LIBs). The coffee powder used as an active anode material for LIBs was obtained from coffee beans, not from a coffee shells. The waste coffee powder was dried in air and heat-treated in an $Ar/H_2$ atmosphere to obtain a pore-forming activated carbon powder. The specific capacity of the sample annealed at $700^{\circ}C$ was still 303 mAh/g after 1000 cycles at a current density of 1000 mA/g and with a coulombic efficiency of over 99.5%. The number of pores and the pore size of the waste coffee powder were increased due to chemical treatment with KOH, which had the some effect as an increased specific surface area. The waste coffee powder is considered to be a very promising active anode material because of both its excellent electrochemical properties due to enhanced carrier conduction and its being a cost effective resource for use in LIBs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.52-60
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• 2021

The aim of this study was to derive a new trend by analyzing installations using 3D printing that are out of the limits of size and design according to the trends of developing 3D printing technology. This paper classified the types of installations using 3D printing and analyzed them with two trends: the trend of design and the trend of output. The trends of installations using 3D printing derived from this study are as follows. First, as the implementation of design through an algorithm is accomplished, the transformation appears with the atypical design that is prominent in complex expression. Second, Robotics and FDM 3D Printing is fused, which is changing the existing paradigm. Therefore, the production and utilization of installations using 3D printing proceeded at a faster pace through the interaction between the algorithm design method and freeform 3D printing technology. This study was conducted on installations using 3D printing around the world and played a basic role in the research on the production of installations using 3D printing along with domestic 3D printing technology to be developed in the future. Follow-up studies in various aspects, such as materials and combination methods, will be needed.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.31-39
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• 2021

The aim of this paper is to improve durability of cement paste by imparting hydrophobicity to the surface and sphere of cement-based materials. A cement paste mixed with a silane/siloxane-based water repellent, and the initial hydration performance, flow performance, and age-specific compressive strength were measured. In addition, the water contact angle, SEM, and XRD before and after surface polishing were measured. When 0.5% of the silane/siloxane-based water repellent was mixed into the cement paste, the compressive strength increased, but the compressive strength decreased as the mixing amount increased by 1.5% and 3.0%. When a silane/siloxane water repellent was incorporated into the cement paste, the hydrophilicity was improved and the contact angle was increased due to hydrophobicity. In addition, the contact angle after surface polishing was found to be larger than the contact angle before surface polishing.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.1-6
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• 2021

Concrete structures gradually age due to deterioration of materials or excess loads and environmental factors, and their performance decreases, affecting the usability and safety of structures. Although external tension construction methods are widely used among the reinforcement methods of old bridges, it is insufficient to identify the effects and effects of reinforcement depending on the level of aging. Therefore, in this study, a four-point loading experiment was conducted on the subject with the non-reinforced and external tensioning method to confirm the reinforcement effect of the external tensioning method, assuming the aging of the structure as a reduction in the compressive strength and tensile reinforcement of concrete, to analyze the behavior of the reinforcement and confirm the reinforcement effect. As a result of the experiment, it was difficult to identify the amount of reinforcement in the extreme condition due to early elimination of the anchorage. Therefore, compliance with the regulations on anchor bolts is required when applying the external tension reinforcement method. Crack load and yield load increased depending on whether external tension was reinforced, but before the crack, the stiffness before and after reinforcement was similar, making it difficult to confirm the reinforcement effect.