• 대한치과기공학회지
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• 제21권1호
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• pp.123-130
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• 1999

I attempted to suggest a better method to separate a refractory cast in order to solve the problems caused by bonding between refractory casts and ceramics in the firing-processing of all ceramic crowns as a part of dental prosthodontics. I emphasize the advantages and effectiveness of easy separation after firing by using the separating materials about the refractory cast dies. 1. We must not usse HF(55%) that is used as the chemical separating methods. 2. We decrease such methods as grinding, blasting, bur, and point 3. We can save time, costs and manual labors by using this methods. 4. This method regulates the expansion and constriction of heat because of the chemical reaction of the separating materials. 5. This method contribute to the breaking down without modification by minimizing the chemical and mechanical damages of the marginal and interior parts.

• 한국식생활문화학회지
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• 제37권4호
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• pp.310-323
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• 2022

The purpose of this study was to investigate the preparation and cooking processes used to prepare Eungi in cookbooks published from the 1700s to the 1900s. 'Eungi' is a thin gruel made of starch powder. Fourteen historical cookbooks were included and investigated for the preparation of ingredients and processing methods. Fourteen types of eungi were identified. Arrowroot eui and kuseonwangdogo eui were found in 『Kyuhapchongseo』 written in the early 1800s, and many types of eungi (i.e. job's tears eungi, arrowroot eungi, sorghum eungi, lotus root eungi) were mentioned in 『Kunhakhoedeung』, but unfortunately, ingredients and cooking methods were not included. 'Eungi' was made by boiling starch powder prepared using the 'subi method', that is, dried after grinding main ingredients such as job's tears using a millstone followed by soaking and settling. Eungi boiled with water or omija water were seasoned with the sugar or honey, and salt. These eungis were used for stomach complaints and hangovers and to promote longevity.

• 펄프종이기술
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• 제48권1호
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• pp.93-99
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• 2016

The extraction efficiency depending on the extracting methods and the conditions of extraction was investigated. The common steam extraction was compared to the distillation extraction method. The effects of the samples size and the extraction time on the extract yield were also investigated by using UV-Vis spectrophotometer. One of the functional components of pine needle extract as the natural phenol base components were detected by the UV-VIS at around 235 nm wavelength range. The absorbance intensity at around 235 nm wavelength of the pine needle extract was used as the indicator of the extraction efficiency in this experiment. The distillation extraction showed the higher extract yield than the steam extraction. The grinding treatment of pine needles also resulted in the better extract performance, but the severe grinding showed a little decrease in the extract yield especially in case of the distillation extraction method. More than half of the extract was collected at the first stage of the extraction, that was the first 15 minutes in the total 60 minutes extraction.

• 한국식품영양과학회지
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• 제32권3호
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• pp.363-369
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• 2003

홍삼 분쇄의 신 가공 기술로서 비충격 분쇄방식인 cell cracker의 공장 적용 가능성을 제시하고 홍삼분말의 품질고급화에 기초자료로 활용하고자 기존의 충격 분쇄방식 인 hammer mill과 cell cracker에 의한 분쇄방식으로 홍삼분말을 제조한 후 이화학적 특성을 조사한 결과, 수분함량의 경우 hammer mill로 분쇄한 홍삼분말은 3.16%로 cell cracker로 분쇄한 홍삼분말 6.30%보다 현저하게 낮게 나타나 현행 식품 공전에서는 홍삼분말의 수분함량을 8%이하로 규정하고 있어 cell cracker에 의한 분쇄가 수율제고라는 측면에서는 보다 경제적인 분쇄방법으로 판단된다. 그 외 cell cracker로 분쇄한 경우 조단백질, 총당, 산성다당체가 약간 높게 나타났으나 큰차는 없었으며, 조지방, 환원당, 조섬유, 회분함량은 hammer mill로 분쇄했을시 약간 높게 나타났으나 큰 차이는 없었다. 총 지방산 함량을 비교해볼 때 hammer mill로 분쇄한 시료는 87.90%이고 cell cracker로 분쇄한 시료는 87.50%로 큰 차이를 보이지 않았다. 총 아미노산 함량을 조사한 결과 hammer mill로 분쇄한 시료는 670.96mg%이고 cell cracker로 분쇄한 시료는 676.50mg%이었으며, 필수아미노산의 경우도 각각 212.25 mg%와 206.25 mg%로 조사되어 거의 차이를 나타내지 않았다. Total ginsenosides 경우 hammer mill로 분쇄한 시료는 1.263%였으나 cell cracker로 분쇄한 시료는 1.311%로 약간 높게 나타났다. 그 외에 유리당 및 무기성분 등에서도 큰 차이를 보이지 않았다.

• 한국도로학회논문집
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• 제19권2호
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• pp.7-15
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• 2017

PURPOSES : Infiltration of moisture, polluted material, and deicer into concrete, accompanied by freeze and thaw can cause significant deterioration of concrete pavement. In order to protect concrete from deterioration, it is necessary to prevent the infiltration of these concrete external materials. The moisture-repellent agent, which is a surface treatment and maintenance material added to concrete structures to render them water resistant, has advantages such as prevention of water infiltration and security against air permeation. Nano-coat, which is referred to as silicon hydride, is typically used as a moisture-repellent agent. Therefore, in this study, an attempt is made to use penetration-type Nano-coat as an alternative in order to evaluate its applicability through environmental resistance tests. METHODS : This study aimed to evaluate the applicability of penetration-type Nano-coat, which can provide water repellency to concrete, in concrete pavements, through various environmental resistance tests such as freezing and thawing resistance, chloride ion penetration resistance, and surface scaling resistance tests. The applicability of penetration-type Nano-coat was demonstrated based on the specification of KS F 2711, KS F 2456, and ASTM C 672. RESULTS :In the case of penetration-type Nano-coat applied on sound concrete, an increase in concrete durability was demonstrated by the negligible chloride ion penetrability and the absence of scaling, as revealed by visual observation of the surface, after 50 cycles of scaling resistance test. In addition, test result of the application of penetration-type Nano-coat on deteriorated concrete established that concrete surface pretreated by grinding provided improved durability than non-treated concrete. CONCLUSIONS :This study indicates that penetration-type Nano-coat is applicable as an effective alternative, to increase the durability of concrete structures. In addition, it was known that pretreatment of deteriorated concrete surface, such as grinding, is required to improve the long-term performance of concrete pavement.

• The Journal of Advanced Prosthodontics
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• 제6권6호
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• pp.434-443
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of $6mm{\times}4mm$ and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with $30{\mu}m$ silica oxide particles ($Cojet^{TM}$ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at ${\alpha}=.05$. RESULTS. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION. Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

• 자원리싸이클링
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• 제23권3호
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• pp.44-50
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• 2014

본 연구에서는 기존의 cutting 분쇄방식 대신 여러 가지 문제점을 개선한 shear방식 및 2단 disk mill 방식으로 폐타이어를 미분화시켰다. 각 파쇄 또는 분쇄 단계별로 다양한 크기의 고무 칩을 얻을 수 있었다. Shear방식 및 2단 disk mill 방식은 회전 속도와 방향이 다른 두 개의 드럼형의 칼날로 이루어져 있어서 기존의 cutting 방식보다 거친 표면의 미분화 폐타이어 분말을 얻을 수 있었다. 본 연구에서는 주로 shear방식으로 미분화된 폐타이어 분말의 형상을 SEM을 통해 비교하였다. 추가적으로 적절한 크기의 폐타이어 분말이 얻어졌는지를 확인하기 위해 입도분석을 수행하였다.

• The Journal of Advanced Prosthodontics
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• 제14권6호
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• pp.335-345
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• 2022

PURPOSE. This in vitro study aimed to evaluate the surface characteristics of a full veneer crown fabricated chairside (CS) from a (Y, Nb)-TZP zirconia block in response to conventional zirconia grinding and polishing. MATERIALS AND METHODS. Zirconia crowns (n = 40) were first prepared and divided into two groups of materials: Labside (LS) and CS, after which each specimen went through a five-step grinding and polishing procedure. Following each surface treatment, surface characteristics were analyzed using confocal laser microscopy (CLSM), average surface roughness (Ra) values were processed from the profile data through Gaussian filtering, and X-ray diffraction pattern analysis was performed to evaluate the monoclinic (M) phase content. Then, a representative specimen was selected for field-emission scanning electron microscopy (FE-SEM), followed by a final analysis of the roughness and X-ray diffraction of the specimens using the independent t-test and repeated measures analysis of variance (RM-ANOVA). RESULTS. In every group, polishing significantly reduced the Ra values (P < .001). There was no significant difference in Ra between the polished state CS and LS. Furthermore, CLSM and FE-SEM investigations revealed that even though grain exposure was visible in CS specimens throughout the as-delivered and ground states, the exposure was reduced after polishing. Moreover, while no phase transformation was visible in the LS, phase transformation was visible in CS after every surface treatment, with the M phase content of the CS group showing a significant reduction after polishing (P < .001). CONCLUSION. Within the limits of this study, clinically acceptable level of surface finishing of (Y, Nb)-TZP can be achieved after conventional zirconia polishing sequence.

• 공업화학
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• 제21권2호
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• pp.148-153
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• 2010

본 연구는 녹차씨의 다양한 용도개발을 위한 기초자료를 얻기 위해 추출방법에 따른 녹차씨유의 물리화학적 특성 및 저장에 따른 안정성 테스트를 하였다. 녹차씨유의 수율은 SGS법을 이용할 경우 수율이 가장 높게 나타났고 비중은 추출방법에 관계없이 $0.91{\sim}0.94g/cm^{3}$ 범위였다. 명도는 SG법을 이용할 때가 가장 밝았으며, 적색도는 PRGS법을 이용할 경우가 가장 높게 나타났고 황색도의 경우는 SG법을 이용할 경우가 가장 높았다. 여러 지방산 중에서 C16 : 0, C18 : 1, 및 C18 : 2가 농도가 가장 높았다. 특히 C18 : 1 농도는 PGS (43.35%) > SGS (42.7%) > SG (39.0%)법의 순으로 다른 지방산에 비해 높은 수준이었다. 포화 지방산 농도는 SG (40.46%) > PGR (31.49%) > SGS (29.96%)법 순이었고 불포화 지방산의 경우는 SGS (69.9%) > PGR (68.39%) > SG (59.41%) 법 순이었다. SGS 및 SG법에 의해 추출된 녹차씨유의 산가는 저장기간이 10일 이후부터는 $6{\sim}8mgKOH/g$ 범위였다. 그러나 PGR법에 의해 추출된 녹차씨유의 산가는 저장기간과 비례하여 저장 60일 후에 49.3 mgKOH/g였다. SGS 및 SG법에 의해 추출된 녹차씨유의 과산화물가는 저장기간 10일부터 60일까지는 60~100 mEq/g 범위였다. 그러나 PGR법에 의해 추출된 녹차씨유의 과산화물가는 저장기간이 10일에서 30일로 증가할 경우 평균 60에서 240 mEq/g로 증가했다. 녹차씨유의 산패축진 작용도는 추출방법에 관계없이 $Fe^{2+}$ > $Cu^{2+}$ > $Cr^{2+}$ > $Zn^{2+}$ > $Ni^{2+}$의 순서로 나타났다. 특히 $Fe^{2+}$이 함유된 녹차씨유에 BHA을 첨가할 경우 과산화물가는 평균 60%가 감소하였고 $Cu^{2+}$의 경우는 평균 63%가 감소하였다. 이상의 결과는 녹차(Camellia sinensis) 씨유는 화장품, 세제, 그리고 식의약품 재료로써 가치가 있다고 사료된다.

• 한국기계가공학회지
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• 제7권3호
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• pp.67-74
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• 2008

Polycrystalline diamonds(PCD) tools are widely used in machining a large variety of advanced materials. However, the manufacture of PCD tool blanks is not an economical process. The shaping of PCD blanks with conventional machining methods(such a grinding) is long, labor-intensive process. This paper reports experimental investigation of the influence of electrical machining conditions on the metal removal rate of WEDM of PCD. Experimental results show that the longer pulse-on time and the shorter pulse-off time increase the metal removal rate and worsen the surface quality. The smaller grain size of diamond yields the metal removal rate and shows the better surface quality. Higher electrical conductivity of water yields worse surface roughness.