• 대한환경공학회지
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• 제38권2호
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• pp.87-95
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• 2016

탁도는 송 배수 관로의 부식 등에 의해 발생되는 것으로 알려진 'Discolored Water'현상을 수용가의 물 사용자가 인지할 수 있는 주요 지표로서 활용되고 있다. 즉, 'Discolored Water'는 수돗물 사용자가 육안으로 인지할 수 있는 정도의 탁도를 가진 상태로 정의할 수 있으며, 사용자는 수돗물에 존재하는 불특정의 용존 물질보다는 미세한 입자들에 대한 시각적인 인지인 탁도를 통해서 'Discolored Water'를 인식하게 된다. 이에 본 연구에서는 실제 국내 상수도 시스템 내에서 관측된 다항목의 수질데이터(탁도, pH 및 잔류염소)를 대상으로 하여 탁도 이외의 수질데이터들을 예측모형의 설명변수로 설정한 후 데이터 마이닝 기법(data mining)을 통해 기계학습(machine learning)을 수행하여, 상수도 시스템 내에서의 탁도 변화를 예측하는 모형을 수립하고자 하였다. 수집된 수질 데이터를 대상으로 데이터 마이닝 기법인 Decision Tree를 이용해 탁도 예측모형을 구축한 결과 pH 및 잔류염소를 설명변수로 적용한 모형이 가장 높은 예측결과를 나타내었다. 하지만 예측모형들은 peak 관측치에 대해서는 예측오차가 다소 증가하였는데 이를 보완하기 위해 고주파통과필터를 이용한 전처리 과정을 적용하였다. 그 결과 탁도 데이터의 시계열변화 및 peak 관측치에 대한 예측오차가 감소하는 것으로 나타났다.

• Restorative Dentistry and Endodontics
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• 제43권2호
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• pp.16.1-16.9
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• 2018

Objectives: Understanding the reason for an unsuccessful non-surgical endodontic treatment outcome, as well as the complex anatomy of the root canal system, is very important. This study examined the cross-sectional root canal structure of mandibular first molars confirmed to have failed non-surgical root canal treatment using digital images obtained during intentional replantation surgery, as well as the causative factors of the failed conventional endodontic treatments. Materials and Methods: This study evaluated 115 mandibular first molars. Digital photographic images of the resected surface were taken at the apical 3 mm level and examined. The discolored dentin area around the root canal was investigated by measuring the total surface area, the treated areas as determined by the endodontic filling material, and the discolored dentin area. Results: Forty 2-rooted teeth showed discolored root dentin in both the mesial and distal roots. Compared to the original filled area, significant expansion of root dentin discoloration was observed. Moreover, the mesial roots were significantly more discolored than the distal roots. Of the 115 molars, 92 had 2 roots. Among the mesial roots of the 2-rooted teeth, 95.7% of the roots had 2 canals and 79.4% had partial/complete isthmuses and/or accessory canals. Conclusions: Dentin discoloration that was not visible on periapical radiographs and cone-beam computed tomography was frequently found in mandibular first molars that failed endodontic treatment. The complex anatomy of the mesial roots of the mandibular first molars is another reason for the failure of conventional endodontic treatment.

• 한국균학회지
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• 제46권4호
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• pp.459-466
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• 2018

2017년 1월 정읍의 한 농가 저장창고에서 검게 변한 귀리종자가 발견되었다. 조사된 100개의 종자 중 45개 종자에서 Pyrenophora속 균이 검출되었다. 종자에서 얻어진 모든 균주들은 internal transcribed spacer (ITS) 부위와 glyceraldehyde 3-phosphate dehydrogenase (GPDH) 유전자 염기서열을 기초로 Pyrenophora avenae로 동정되었고, 형태적, 배양적 특성에 의해 확인되었다. ITS와 GPDH 염기서열 기반의 계통수를 통해 P. avenae 균주는 유전적으로 뚜렷한 4개의 그룹으로 구분할 수 있었다. 병원성 검정 결과, P. avenae는 귀리의 종자흑변과 잎마름병을 일으키는 병원균으로 확인되었다. 이것은 한국에서 P. avenae가 귀리잎마름병을 일으킨다는 최초 보고이다.

• The International Journal of Costume Culture
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• 제7권2호
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• pp.151-157
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• 2004

This research is to conservate the old hat and restore its shape and place it on a supportive form in a stable protective container. The hat is a homemade construction, utilizing three different machine made laces, and two cotton net fabrics. The exterior, particularly the top crown piece, as well as the lace along the brim's edge has been generally soiled and discolored. Inside the crown, the cotton net has broken threads, and thread loss in several areas. The paper covering the two wires is very weak, and has discolored the lace in the areas of contact. The plastic buckles of the velvet ribbon have also discolored the areas where there is contact. The wash/bleach bath procedure was very effective. Virtually all of the light brown surface discoloration stains were removed. The darker brown spots, particularly concentrated around the two paper covered wires and assumed to be rust, were $90\%$ removed by the treatment. The brown spots apparently were due to the degradation of the paper covering, and not caused by the wire itself. The buckram foundation lost about $50\%$ of its stiffness, but this was not a major concern due to the fact that this hat should remain it its mount, which has been designed to serve for both storage and exhibition purposes.

• 한국가구학회지
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• 제19권6호
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• pp.460-465
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• 2008

When wood is exposed to natural weathering and UV radiation discoloration progresses. The color variation of heat-treated wood was investigated. Four domestic species were selected and heat-treated at $220^{\circ}C$ and naturally weathered for 42 days. Their colors were measured with a portable colorimeter. The color variations were different between species. The Korean red pine specimens were highly discolored by the natural weathering even though they were heat-treated. In contrast to Korean red pine, Korean pine is less discolored. The maximum color difference of larch was lower than Korean red pine. All specimens of birch exceeded the color difference criterion of 15 after 25 hours with the maximum of 28.

• 한국산림과학회지
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• 제99권2호
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• pp.226-234
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• 2010

This study was conducted to examine the effects of pruning season on the compartmentalization of pruning wounds in Acer palmatum and Pinus strobus. A total of eighty five field-grown trees for each species were allocated to five different seasons, early- and late-winter, mid-spring, mid- and late-summer, for pruning treatments. Wound closure rate (WCR) of the two species for one year after treatment, area of discolored stem tissue on the medial longitudinal surface and cambial dieback length under the pruning wound of A. palmatum were measured. Changes of total phenols and variations of extractives, holocellulose and lignin at the treated branch unions were examined. In WCR of A. palmatum, late-winter (March, 39.8%) and mid-spring (May, 39.7%) were higher than any other seasons, while early-winter (November, 28.4%) was significantly lower than late-winter and mid-spring. P. strobus showed similar results with A. palmatum. The WCR of early-winter (57.2%) was the lowest significantly among the five seasons, and mid-spring (73.5%) and late-winter (71.4%) showed higher a WCR than other seasons. In the discolored/wound area ratio of A. palmatum, early-winter (73.2%) was the highest by far, and mid- (July) and latesummer (September, 36.7%, respectively) were the lowest among the five seasons. In the length of cambial dieback, two dormant seasons, early- and late-winter were longer than any other seasons. Phenol contents at the treated branch union were changed in line with the seasonal fluctuation of the tree. Total phenols in the below core of the treated union were higher than those of the branch union with living branch, while little differences were seen in the above core. At the branch core of the treated union, phenols of A. palmatum decreased one month after the treatments, but P. strobus maintained similar to or a little higher than those at the controls. The major changes in chemical composition at pruning wounds were extractives and lignin increased by less than 20% in A. palmatum, while extractives in P. strobus remarkably increased by 70%.

• The Journal of Advanced Prosthodontics
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• 제14권5호
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• pp.324-333
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• 2022

PURPOSE. The purpose of this study is to evaluate translucency and masking ability of translucent zirconia compared to conventional zirconia and lithium disilicate materials. MATERIALS AND METHODS. Three types of zirconia blocks with different yttria contents (3Y, 4Y, 5.5Y) and LS blocks (Rosetta SM) were used. Ten specimens for each group were fabricated with 10 mm diameter, with both 0.8 mm and 1.5 mm thicknesses (± 0.02 mm). All groups of zirconia specimens were sintered and polished according to the manufacturer's instructions. To calculate the translucency parameter (TP), CIELAB value was measured with a spectrophotometer on black and white backgrounds. To investigate the color masking abilities, background shades of A2, normal dentin, discolored dentin, and titanium were used. The color difference (ΔE) was calculated with the CIELAB values of A2 shade background as a reference compared with the values in the various backgrounds. One-way ANOVA and Bonferroni tests were conducted (P < .05). RESULTS. The TP values of zirconia specimens increased as the yttria content increased. All materials used in the study were able to adequately mask normal dentin shade (ΔE < 5.5), but were incapable of masking severely discolored dentin (ΔE > 5.5). On the titanium background, all materials of 1.5 mm thickness were able to mask the background shade, but with a thickness of 0.8 mm, only 3Y-TZP and 4Y-PSZ were able to mask titanium background. CONCLUSION. All zirconia materials and lithium disilicate specimens used in this study were unable to adequately mask the shade of severely discolored dentin. It is recommended to use 3Y-TZP or 4Y-PSZ with a sufficient thickness of 0.8 mm or more to mask titanium.

• 한국식품과학회지
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• 제34권6호
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• pp.977-983
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• 2002

식용색소 및 공업용 염료의 인공적 착색여부를 조사한 결과, 심황색소, 식용희석황색소, 마리골드색소, 식용황색 4호, 안나토색소, 카로틴색소는 유사한 색으로 착색되었으며 다른 색소는 착색되지 않았다. 물에 의한 추출시험에서는 참조기 색소와 식용색소황색 제4호는 물에서 용출되지 않았다. 착색 후 색소의 물성실험을 한 결과 물 젖은 가제수건이나 휴지로 색소부위 표피를 문지를 경우 참조기 색소는 표면에 전혀 묻어 나오지 않으나 인공적으로 착색된 색소의 경우에는 물에 의해 색이 뚜렷하게 묻어 나왔으며 참조기의 착색 부위 표피를 아세톤으로 추출할 경우 참조기 색소는 아세톤에 옅은 황색용액으로 추출되었다. 또한, 참조기의 색소처럼 물에 용출되지 않도록 염착이 가능한 공업적 합성염료인 반응성 염료와 분산염료의 착색거동에 대해 실험한 결과, 반응성 염료는 조기에 착색되지만 물 젖은 휴지로 착색부위를 문지를 경우 색소가 용출되었고, 아세톤에는 추출되지 않아 참조기 색소와는 쉽게 판별되었으며 분산염료는 염료가 고르게 착색되지 않고 염료가 입자를 형성하며, 물 적신 휴지로 색소부위를 문지를 경우 색소가 용출됨을 알 수 있었다. 카로틴색소(참조기 색소와 구조가 유사한 색소)와 azo염료의 산화 환원 반응에 따른 소색 반응에서는 산화반응에서 azo염료는 sodium percarbonate와 peracetic acid에서는 소색이 되지 않았으나, fenton시약에서는 1시간 후 소색되었고, sodium hypochlorite에서는 바로 소색되었다. 이에 비하여 카로틴색소는 sodium percarbonate 및 fenton시약에서는 소색되지 않았으나, sodium hypochlorite에서는 2시간 후 소색되었고, peracetic acid에서는 바로 소색되었다. 또한, sodium hydrosulfite, sodium carbonate를 사용한 환원반응시험에서는 azo염료는 소색되었으나, 카로틴색소는 소색되지 않았다. 이러한 결과를 통해 두 색소의 특징적 group을 제거할 때 나타나는 소색 결과를 토대로 진품참조기와 모조참조기의 판별에 이용할 수 있을 것으로 사료된다.

• Restorative Dentistry and Endodontics
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• 제27권4호
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• pp.441-447
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• 2002

The bleaching of discolored nonvital teeth is conservative treatment that satisfy the cosmetic desire. The most common method for this treatment, walking bleaching, is using 30% hydrogen peroxide and sodium perborate. Many alternatives are suggested for preventing the external cervical root resorption that is the common complication of the nonvital teeth bleaching with 30% hydrogen peroxide The same extent of oxidation reactions as that resulted by the bleaching with the application of 30% hydrogen peroxide and sodium perborate can also be acquired more safely by materials that contain 10% carbamide peroxide, used primarily for the bleaching of vital teeth. Therefore, this study was performed to evaluate the efficacy of 10% and 15% carbamide peroxide bleaching gel in nonvatal teeth bleaching. The internal bleaching of intentionally discolored teeth was performed in vitro with 10% carbamide peroxide (Group 1), 15% carbamide peroxide (Group 2), mixture of distilled water and sodium perborate (Group 3), and mixture of 30% hydrogen peroxide and sodium perborate (Group 4). The bleaching materials were refreshed following 3, 6, 9 and 12 days. To evaluate the bleaching effect, the color change of the crowns was measured at 1, 2, 3, 4, 7 and 15 days of bleaching using the colorimeter. The results were as follows：1. L$^*$ and $\Delta$E$^*$ values were increased with time in all bleaching agents (p<0.01). 2. There was no significant difference in L$^*$ and $\Delta$E$^*$ value among bleaching agents. 3. $\Delta$E$^*$ value higher than 3 was shown after 3 days of bleaching with 10% carbamide peroxide gel, 1 day with 15% carbamide poroxide gel, 4 days with mixture sodium perborate and distilled water and 4 days with mixture sodium perborate and 30% hydrogen peroride, respectively. These results revealed that the use of 10% and 15% carbamide peroxide bleaching gel in non-vital teeth bleaching is as effective as mixture of distilled water and sodium perborate and mixture of 30% hydrogen peroxide and sodium perborate. Accordingly, carbamide peroxide could be used clinically to bleach discolored non-vital teeth.

• 식물병연구
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• 제20권4호
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• pp.270-274
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• 2014

본 연구의 목적은 신갈나무에서 참나무시들음병 병원균인 Raffaelea quercus-mongolicae의 지역별 균주와 기타 Raffaelea 속 근연종의 병원성을 평가하는 것이다. 이 연구에서는 신갈나무에 다양한 균주를 접종한 후, 변재부 내 변색정도로 각 균주의 병원성을 판단하였다. 그 결과 변색부의 평균 측면 확산 정도는 국내에서 분리한 Raffaelea quercus-mongolicae 병원균(8.69 cm)이 일본 병원균(7.51 cm)이나 기타 Raffaelea 속 근연종(3.35 cm)의 평균보다 높았고, 국내 지역별 Raffaelea quercusmongolicae 균주간에는 변색부 측면 확산정도가 4.71-14.90 cm로 병원성의 차이를 보였다. 균주간의 변색부 면적 확산정도는 $1.57-8.42cm^2$로 서로 다른 병원성의 차이를 보였으며, 가장 높은 병원성은 강원도에서 분리한 YY와 전라북도에서 분리한 wj43에서 나타났다.