• 구강회복응용과학지
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• 제21권1호
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• pp.69-81
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• 2005

The objective of this study was to evaluate the toothbrush abrasion characteristics of class V restorations. Thirty extracted human premolars, which were collected from oral surgery clinics were used. We mounted five teeth in a metal ring mold of 50 mm in diameter and 15 mm in height using chemically cured acrylic resin. Class V cavities were prepared in lingual cervical root surfaces and restored using one of following restorative materials : Dentin Conditioner/Fuji II LC (Group FL), All Bond II/Z-250 (Group ZT), One-up Bond F/Palfigue Estelite (Group PE), F2000 Primer/Adhesive (Group FT), and Prime & Bond 2.1/Dyract AP (Group DR). They were stored under distilled water at $37^{\circ}C$ for seven days. The toothbrush abrasion test was conducted using a wear testing machine of pin-on disk type under a load of 1.5 N for 100,000 cycles. We have examined the bonded interfaces, the changes of surface roughness and color of abraded surfaces. From this experiment, the following results were obtained. 1. The change of surface roughness showed high degree: RMGIC>compomer>composite resin (p<0.05). 2. Because of the protrusion and missing of filler particles, SEM observation of abraded surfaces of RMGIC and compomers revealed the increase of surface roughness due to the selective removal of matrix resin. 3. The color change by toothbrush abrasion was affected in large part by the change of $L^*$ and $b^*$ of resin composites (p<0.05). 4. The color change by toothbrush abrasion was so small to detect by human eyes. 5. SEM observation of abraded surfaces revealed the interface bonding was the best in the FT group.

• Journal of Ecology and Environment
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• 제46권4호
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• pp.292-303
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• 2022

Background: Climate change significantly influences the geographical distribution of plant species worldwide. Selecting indicator species allows for better-informed and more effective ecosystem management in response to climate change. The Korean Peninsula is the northernmost distribution zone of warm temperate evergreen broad-leaved (WTEB) species in Northeast Asia. Considering the ecological value of these species, we evaluated the current distribution range and future suitable habitat for 13 WTEB tree species designated as climate-sensitive biological indicator species. Results: Up-to-date and accurate WTEB species distribution maps were constructed using herbarium specimens and citizen science data from the Korea Biodiversity Observation Network. Current northern limits for several species have shifted to higher latitudes compared to previous records. For example, the northern latitude limit for Stauntonia hexaphylla is higher (37° 02' N, Deokjeokdo archipelago) than that reported previously (36° 13' N). The minimum temperature of the coldest month (Bio6) is the major factor influencing species distribution. Under future climate change scenarios, suitable habitats are predicted to expand toward higher latitudes inland and along the western coastal areas. Conclusions: Our results support the suitability of WTEB trees as significant biological indicators of species' responses to warming. The findings also suggest the need for consistent monitoring of species distribution shifts. This study provides an important baseline dataset for future monitoring and management of indicator species' responses to changing climate conditions in South Korea.

• 한국지리정보학회지
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• 제10권2호
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• pp.1-10
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• 2007

연안의 무분별한 개발로 인해 해안의 침식 및 퇴적의 경향이 발생되고 있어 해안선 변화에 따른 자연보존 및 개발의 대책 수립이 요구되고 있다. 본 연구에서는 강원도 강릉시 연안 지역을 선정하여 약 2개월의 주기적인 간격으로 6회의 DGPS 측량을 실시하였고, 관측 자료는 강릉상시관측소를 기준으로 약 50cm 정확도로 후처리하여 1998년 수치지형도 및 2006년 수치해도와 상호 비교하였다. DGPS 측량값들은 수치지형도 해안선과 비교하여 볼 때 국부적으로는 강문항 도류제 설치부근과 남항진의 남측에 침식이 발생하였고 남항진 지역의 방파제 부근에는 많은 해안 퇴적이 일어났으며, 다른 지역의 경우도 부분적으로 해안 퇴적이 발생하고 있음을 알 수 있었다. 따라서 GIS 자료입력에 알맞은 데이터 취득 방법으로 DGPS를 이용하여 수평자료 획득이 용이하고, 해안 개발에 따른 장기적이고 지속적인 관측을 통한 시계열적 해안선 변화를 측정하는데 효과적으로 사용될 수 있을 것이다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2005년도 추계학술대회 논문집
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• pp.525-526
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• 2005

• 한국표면공학회지
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• 제15권2호
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• pp.69-76
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• 1982

With a view to manufacturing membranes for separation of gas mixtures, Al foils were anodized in a 2% oxalic-acid electrolyte at 40V and 80V. When anodizing was completed and Barrier layer existed at the extreme back site of the foil, the anodized foil was made to react with only electrolyte, with switching off the electric power. When the size and density of pores were changed through voltage change, the membr-anes did not show large difference in the permeability. Reacting with electrolyte, the existing Barrier layer turns into porous layer. During this process, several small pores grow from one relatively large pore, getting to the back site. The number and size of the small pores getting to the back surface increase as time passing. This change of Barrier layer into porous layer is thought to be directly related to the permeability change of the membranes. The selectivity of an anodized Al membrane was not related to the voltage change, and was high, being similar to the theoretical selctivity of metallic membranes, according to my observation.

• 한국조경학회:학술대회논문집
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• 한국조경학회 2007년도 Journal of Landscape Architecture in Asia Vol.3
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• pp.214-219
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• 2007

Psychological and physiological effects of plants were studied by investigating human responses while observing plants. Eighteen healthy adult male(aged between $19{\sim}25$ years) participated in this study. Semantic differential method(SD method) and multi-channel near-infrared spectroscopy(NIRS) were used to survey verbal and non-verbal response, respectively. Cerebral hemodynamics as a new evaluation index of brain activity was recorded for right brain hemisphere where visual information is mainly delivered. Thirty seconds of cerebral blood flow in forty seven channels were calculated when watching five types of picture images with different rates of hedge against gray block wall; 0:10, 3:7, 5:5, 7:3, 10:0. In the SD results, similar evaluations were found in all subjects. However, the change of cerebral hemodynamics as a non-verbal response varied among subjects. Largely two patterns of hemodynamics change were found with increasing plants rate in picture images; group A showed significant decreases of blood flow volume in many cortical regions, Group B had significant increase of blood flow volume in the occipital region for the scenes seen comparatively more plant. Our findings on the cerebral hemodynamics may indicate that there are two patterns of brain activity during observation of plants; group A in which brain areas associated with visual information and thinking work simultaneously to the visual stimuli; group B in which brain areas associated only with visual information work.

• 대한한방체열의학회지
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• 제6권1호
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• pp.69-75
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• 2008

Purpose: We investigated the effect of far-infrared radiating products on cold hypersensitivity of lower limbs using CST. Methods: 7 patients with cold hypersensitivity of lower limbs were investigated in this study. Exclusive criteria was skin diseases, spinal nervous disease and external wounds. They were asked to answer the VAS of cold hypersensitivity at baseline and after 3 weeks. We measured temperature of lower limbs with Spectrum 9000 MB (Dorex Inc, USA). We performed cold stress test (CST) by 3 thermographic observation using DITI : 1st was taken after 15 minutes resting at $25^{\circ}C$, the 2nd was immediately taken after 1 minute soak in $20^{\circ}C$ water, the 3rd was taken at 15 minutes after soak. We performed 3 times of CST : 1st CST was perfomed at baseline, 2nd CST was perfomred after 1 week and just observation, 3rd CST was performed after 1 week using far-infrared radiating products (lasner, UMT, Korea). Results: After using products, temperature of foot incresed more than thigh area, but there was no significance. There was no statistical difference of VAS, change of temperature and CST between before and after using far-infrared radiating products. Conclusion: There was no statistical effect of far-infrared radiating products on change of temperature of lower limbs.

• 대한치과기공학회지
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• 제35권4호
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• pp.353-358
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• 2013

Purpose: This study was observation shear bonding strength by compositional change and firing step of a Ni-Cr alloy for porcelain fused metal crown. The aim of study was to suggest the material for firing step of Ni71-Cr14 alloy to development of alloy for porcelain fused to metal crown. Methods: The test was on the two kinds of Ni-Cr alloy specimens. The surfaces of two alloys were analyzed by EDX in order to observe oxide characteristic. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element O within $Ni_{71}Cr_{14}$ alloy measured 23.32wt%, and $Ni_{59}Cr_{24}$ alloy was measured 23.03wt%. And the maximum shear bonding strength was measured 58.02MPa between $Ni_{59}Cr_{24}$ alloy and vintage halo(H4 group). Conclusion: The surface property and oxide characteristic three kind of Ni-Cr alloy was similar. and shear bonding strength showed the highest bonding strength in H4 specimens.

• 한국식품영양과학회지
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• 제26권6호
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• pp.1077-1085
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• 1997

This study was carried out to elucidate the utilization of the fusant for shortening the ripening time by making an observation of the microstructure and the profile of component change. In ripening cheese, moisture content of the sample treated with tested strain is not a remarkable difference among the test samples. With an increase of the ripening time, L. helveticus showed the highest increase in protein content, followed by fusant, and then L. bulgaricus. The fat content of all starters was gradually decreased while it was it was rapidly decreased after 7 days. The pH of all starters was gradually decreased when the ripening time increased. The titratable acidity was greatly increased between a 9th day and a 15th day ripening. In investigating the light microscopic microstructure of ripened cheese samples, the sample treated with fusant indicated little difference from the other starters in decomposition of protein and fat components by microbial enzymes. In SEM observation, the structure of all cheese samples was uniform and the rough texture was converted into smooth texture by the interaction of cheese components and the abscission of single bond in casein matrix when the ripening time is increased. The fusant showed similar results in the examination of component change and its microstructure compared with the other starters. Therefore, it was revealed that the fusant can be partially used as a cheese starter instead of conventional starters by replacing them or combining them together with the other starters for shortening the ripening time.

• 수산해양기술연구
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• 제56권2호
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• pp.126-137
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• 2020

This study collected and analyzed the fishing process of existing fishing boat and newly built fishing boat by using the video observation methods to understand the improvement of fishing operation efficiency and safety according to the scale change of coastal composite fishing boat. The fishing operation efficiency was calculated by analyzing the frequency of movement, the movement distance and the moving time per basket used in the fishing process to derive the improvement of the newly built fishing boat compared to the existing fishing boat. It was confirmed that the mean frequency of movements decreased to 13.9%, the average moving time decreased to 21.8%, the mean movement distance increased to 20.5% and the movement through the top of gunwale did not occur. Movement of frequency, increased and time according to the fishing operation were directly affected by the width of side passages and the presence or absence of walking obstruction such as bulwark stay, hatch coaming and fishing gears on deck. The results of this study are expected to be used as basic data for redesigning into a safe and efficient coastal composite fishing boat in the future.