• 한국정밀공학회지
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• 제8권2호
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• pp.89-105
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• 1991

A method to apply the approximation formulae[1] for tooth fillet and root stresses of a thin-rimmed rack to the calculation of stress state of thin-rimmed external and internal spur gears is introduced. The stress values by the method proposed in this paper have shown good agreement with those by the REM analysis and also by the stress measurement of strain survey investigation. By this method, reliable stress state at tooth fillet and root areas in the thin-rimmed external and internal spur gears can be easily calculated, and a practical design method for the bending strength of such thin-rimmed gears is established.

• Journal of Advanced Marine Engineering and Technology
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• 제17권3호
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• pp.80-87
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• 1993

The various configuration of thin-shaped bevel gears are used usually for such as main reduction gear of the hovercraft. But the reasonable and concise guide to thedesign of the se bevel gears is not yet obtained, since the tooth of bevel gear has complex form. The purpose of these investigation is to be establish the design guide and to propose the desirable configuration form for thin-shaped straight bevel gear. In this report, the desirable configuration is examined experimentally by clearing up the effect of web and rim thickness, rim support condition upon the load distribution and root stress distribution along the tooth trace. The results are summarized as follows. (1) The crowning of tooth trace exerts a significant effect on the root stress distribution of thin-shaped bevel gear. (2) As the desirable configuration of the thin-shaped bevel gear, it is to be recommended that the rim is supported at the heel side of tooth trace. (3) But, as special type, it is desirable that the rim is supported at the toe side.

• Journal of Plant Biotechnology
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• 제49권3호
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• pp.230-239
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• 2022

Holostemma annulare (Family Asclepiadaceae) is an invaluable vulnerable medicinal plant; the root tubers are used in Ayurveda medicine and by folk healers to treat various ailments. In this study, Schenk and Hildebrandt medium fortified with the cytokinins 6-benzyl adenine, kinetin, and auxins, including indole 3-butyric acid, indole 3-acetic acid, α-naphthaleneacetic acid, and 2,4-dichlorophenoxyacetic acid, were checked for their efficiency on root tuber induction from different explants. Adventitious root tubers were more successfully induced from in vitro leaf segments and shoots when cultured in Schenk and Hildebrandt medium supplemented with 0.5 mg/l of α-naphthaleneacetic acid. In addition, preliminary phytochemical analysis of in vitro root tubers and identification of different secondary metabolites were conducted. Thin layer chromatography and high performance thin layer chromatography analysis of the crude methanolic extracts of the in vitro root tuber identified the presence of lupeol, a bioactive triterpene. Adventitious root tuber induction offers a novel method for the in vitro production of bioactive metabolites that can be scaled up by bioreactors, thus ensuring the conservation and sustainable utilization of H. annulare. The study warrants further scale-up production and pharmacological investigation that can be extended for pharmaceutical needs.

• Journal of Biosystems Engineering
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• 제22권1호
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• pp.11-20
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• 1997

Thin layer drying tests of short gain rough rice were conducted in an experimental dryer equiped with air conditioning unit. The drying tests were performed in triplicate at three air temperatures of $35^circ$, $45^circ$, $55^circ$, and three relative humidities of 40%, 55%, 70%, respectively. Previously published thin layer equations were reviewed and four different models widely used as thin layer drying equations for cereal grains were selected. The selected four models were Pages, simplified diffusion, Lewis's and Thompson's models. Experimental data were fitted to these equations using stepwise multiple regression analysis. The experimental constants involved in tow equations were represented as a function of temperature and relative humidity of drying air. The results of comparing coefficients of determination and root mean square errors of miosture ratio for low equations showed that Page's and Thompsons models were found to fit adequately to all drying test data with coefficient of determination of 0.99 or better and root mean square error of moisture ratio of 0.025.

• Steel and Composite Structures
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• 제46권4호
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• pp.577-589
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• 2023

In this study, on-site testing was carried out to investigate the vibration performance of a cold-formed thin-walled steel floor system. Ambient vibration, walking excitation (single and double persons), and impulsive excitation (heel-drop and jumping) were considered to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes) and vertical acceleration response. Meanwhile, to discuss the influence of cement fiberboard on structural vibration, the primary vibration parameters were compared between the systems with and without the installation of cement fiberboard. Based on the experimental analysis, the cold-formed thin-walled steel floor possesses high frequency (> 10 Hz) and damping (> 2%); the installed cement fiberboard mainly increases the mass of floor system without effectively increasing the floor stiffness and may reduce the effects of primary vibration parameters on acceleration response; and the human-structure interaction should be considered when analyzing the vibration serviceability. The comparison of the experimental results with those in the AISC Design Guide indicates that the cold-formed thin-walled steel floor exhibits acceptable vibration serviceability. A crest factor 𝛽_rp (ratio of peak to root-mean-square accelerations) is proposed to determine the root-mean-square acceleration for convenience.

• Journal of Ginseng Research
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• 제9권1호
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• pp.24-35
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• 1985

Rusty root of ginseng has been known as one of the limiting factors in ginseng production in Korea. An attempt was, therefore, made to elucidate biological and chemical natures of the rusty root, and the redox Potential of the ginseng cultivated soils were measured and compared with diseased and non-diseased soils. Reddish discoloration was most frequently observed on the epidermis of ginseng root and the pigments were accumulated in all epidermal cells of the diseased lesions. The lower the redox potential of the ginseng cultivated soil was, the more severe the rusty root was observed. Fe content in the diseased epidermis was 3 times higher than that of healthy one. Organic acids such as oxalic, malonic, succinic, and citric acids were also higher in the mss root than in the healthy one. Thin layer chromatogram of phenolic acid fractions obtained from the epidermal cells of the rusty root of ginseng exhibited 3 to 4 unidentified substances not found in the healthy root. Also lignification of the epidermal cells and the activity of phenylalanine ammonia lyase were greater in the rusty root than the healthy root. Colony formation and conidia production of F. solani, And mycelial growth and sclerotium formation of Sclerotinia sp. isolated from ginseng root were suppressed in a nutritionally minimal medium supplemented with water extract of rusty ginseng root epidermis. It is, therefore, suggested that rusty root of ginseng is caused by unfavorable rhizosphere environmental stress or stresses resulting abnormal metabolism in the root as a selfdefence mechanism of non-specific resistance responses.

• Imaging Science in Dentistry
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• 제47권3호
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• pp.181-187
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• 2017

Purpose: The purpose of this study was to measure the buccal bone thickness and angulation of the maxillary incisors and to analyze the correlation between these parameters and the root position in the alveolar bone using cone-beam computed tomography (CBCT). Materials and Methods: CBCT images of 398 maxillary central and lateral incisors from 199 patients were retrospectively reviewed. The root position in the alveolar bone was classified as buccal, middle, or palatal, and the buccal type was further classified into subtypes I, II, and III. In addition, the buccolingual inclination of the tooth and buccal bone thickness were evaluated. Results: A majority of the maxillary incisors were positioned more buccally within the alveolar bone, and only 2 lateral incisors(0.5%) were positioned more palatally. The angulation of buccal subtype III was the greatest and that of the middle type was the lowest. Most of the maxillary incisors exhibited a thin facial bone wall, and the lateral incisors had a significantly thinner buccal bone than the central incisors. The buccal bone of buccal subtypes II and III was significantly thinner than that of buccal subtype I. Conclusion: A majority of the maxillary incisor roots were positioned close to the buccal cortical plate and had a thin buccal bone wall. Significant relationships were observed between the root position in the alveolar bone, the angulation of the tooth in the alveolar bone, and buccal bone thickness. CBCT analyses of the buccal bone and sagittal root position are recommended for the selection of the appropriate treatment approach.

• 대한치과의사협회지
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• 제54권8호
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• pp.658-665
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• 2016

Treatment of immature permanent teeth with irreversibly damaged pulp has been challenging in dental practice because of the lack of apical constriction, thin dentinal walls, and short roots. This may lead to the extrusion of filling materials, and fracture of the root due to its more fragile feature during shaping of the root canal. Apexification with calcium hydroxide or MTA is one of the treatment options for these cases. Although favorable results of apexification have been reported, these treatment procedures do not guarantee the increase of root length and/or width even after a long term period. Thus, treated teeth are still prone to fractures. Recently, pulp revascularization has been proposed as an alternative treatment for immature teeth with necrotic pulp and periapical pathosis. Pulp revascularization allows the stimulation of the apical development and the root maturation. There have been many treatment protocols using various materials such as antibiotics and calcium hydroxide medicament. In this case report, literature review about pulp revascularization and two related cases are presented.

• Restorative Dentistry and Endodontics
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• 제41권1호
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• pp.68-73
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• 2016

This case report describes a unique C-shaped mandibular second premolar with four canals and three apical foramina and its endodontic management with the aid of cone-beam computer tomography (CBCT). C-shaped root canal morphology with four canals was identified under a dental operating microscope. A CBCT scan was taken to evaluate the aberrant root canal anatomy and devise a better instrumentation strategy based on the anatomy. All canals were instrumented to have a 0.05 taper using 1.0 mm step-back filing with appropriate apical sizes determined from the CBCT scan images and filled using a warm vertical compaction technique. A C-shaped mandibular second premolar with multiple canals is an anatomically rare case for clinicians, yet its endodontic treatment may require a careful instrumentation strategy due to the difficulty in disinfecting the canals in the thin root area without compromising the root structure.

• 한국산림과학회지
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• 제90권4호
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• pp.458-464
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• 2001

본 연구는 토양 산성화 정도가 서로 다른 독일가문비나무 임분에서 토양 깊이에 따른 뿌리의 나이테 발달과 분지형태를 분석함으로서, 임분에 따른 뿌리발달을 비교하고자 하였다. 조사된 독일가문비나무 임분에서 뿌리분지구조는 변형된 뿌리와 변형되지 않은 뿌리에 대한 조사임분간의 통계적 유의성이 인정되지 않았지만, 가장 많이 산성화된 Weidenbrunnen 임분에서는 뿌리가 상해를 입음으로 인해 발생되는 포크형, 권총형, 쇠스랑형과 같은 비정상적인 분지구조가 많이 나타났다. 뿌리의 나이테 분석 결과, 수평뿌리의 연평균 길이생장은 Weidenbrunnen 임분과 Barbis 임분이 6.3cm, Eberg$\ddot{o}$tzen 임분이 9.5cm의 길이 생장을 나타내었으며, 수직뿌리의 연평균 길이생장은 Weidenbrunnen 임분이 4.4cm Barbis 임분이 5.4cm, 그리고 Eberg$\ddot{o}$tzen 임분이 6.7cm의 생장을 보였다. 80cm 토양 깊이에서의 뿌리 횡단면 분포는 Eberg$\ddot{o}$tzen 임분이 굵은 뿌리와 가는 뿌리가 고르게 분포하고 있으며, 횡단면의 합계는 $32.6cm^2$ 이었다. Barbis 임분에서는 굵은 뿌리가 가운데 몰려서 분포하고, 가는 뿌리는 비교적 적게 나타났으며, 그 합계는 $29.2cm^2$이었다. Weidenbrunnen 임분에서는 적은 수의 가는 뿌리만 분포하고 그 값은 $10.9cm^2$에 불과하였다. 뿌리고정계수는 Eberg$\ddot{o}$tzen 임분이 1.04로 다른 두 임분 Barbis(0.3), Weidenbrunnen (0.08)과 비교하여 매우 높은 값을 나타내었다. 본 조사 독일가문비나무 임분 중에서 Weidenbrunnen 임분에서 나타난 비정상적인 형태의 변형된 분지구조와 뿌리의 저조한 생장은 토양산 성화 등으로 인하여 정상적인 뿌리가 생장의 장애를 받아 나타난 결과 때문이라 사료된다.