• International Journal of High-Rise Buildings
• /
• v.7 no.4
• /
• pp.299-311
• /
• 2018

As engineered timber such as Glulam is seeing increasing use in tall timber buildings, building codes are adapting to allow for this. In order for this material to be used confidently and safely in one of these applications, there is a need to understand the effects that fire can have on an engineered timber structural member. The post-fire resilience aspect of glulam is studied herein. Two sets of experiments are performed to consider the validity of zero strength guidance with respect to short duration fire exposure on thin glulam members. Small scale samples were heated in a cone calorimeter to different fire severities. These samples illustrated significant strength loss but high variability despite controlled quantification of char layers. Large scale samples were heated locally using a controlled fuel fire in shear and moment locations along the length of the beam respectively. Additionally, reduced cross section samples were created by mechanically carving a way an area of cross section equal to the area lost to char on the heated beams. All of the samples were then loaded to failure in four-point (laterally restrained) bending tests. The beams that have been burnt in the shear region were observed as having a reduction in strength of up to 34.5% from the control beams. These test samples displayed relatively little variability, apart from beams that displayed material defects. The suite of testing indicated that zero strength guidance may be under conservative and may require increasing from 7 mm up to as much as 23 mm.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.3
• /
• pp.147-154
• /
• 2008

Weathered soil slope loses its shear strength if it is exposed in the air for a long time or in contact with water. And this kind of strength loss is remarkable in dam slope which has very big difference in water level according to the season. In this study, shear strength loss of weathered soil due to saturation had been found out through dryness and wetness repetition direct shear test. Also relation between penetration blow number(Nc) and shear strength parameter had been found out through small sized dynamic cone penetration test device and the correlation equation of Nc had been proposed through artificial neural network analysis to estimate shear strength parameter easily.

• The korean journal of orthodontics
• /
• v.31 no.5 s.88
• /
• pp.525-534
• /
• 2001

Bone remodeling in response to force requires coordinated actions of osteoblasts, osteoclasts, osteocytes, and periodontal ligament cells. Coordination among these cells may be mediated, in part, by cell-to-cell communication via gap junctions. This study was designed to evaluate the expression of gap junction, connection 43 In periodontal tissue during the experimental movement of rat's incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for connexin 43. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats), and 6 experimental groups(24 rats) where 75g of force was applied from helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 12 hours, 1, 4, 7, 14 and 28 days after force application, respectively. And the tissues of a control group and experimental groups were studied immunohistochemically. The results were as follows : 1. In control group, the expression of connexin 43 was rare in gingiva, dentin, cementum, periodontal ligament, and bone cells. 2. In experimental group, the expression of connexin 43 was increased in pulp, periodontal ligament, osteoblasts, and osteoclasts, comparing to that in control. And it was rare in gingiva, dentin, and odontoblasts regardless of the duration of force application, which was not different from that of control group. 3. The expression of connexin 43 in pulp of experimental group began to increase in 4-day after force application and got to the highest degree at 7-day. And it decreased after 14-day to be similar to that of control group at 28-day. 4. The expression of connexin 43 in periodontal ligament was noted in small capillaries adjacent to alveolar bone, showing higher intensity of immunolabelling after 4-day And it was stronger in the pressure side than in tension side of periodontal ligament. After 7-day, decrease in connexin 43 expression was observed. 5. The expression of connexin 43 in alveolar bone began to increase 1-day, reached to the highest degree at 4-day, and decreased at 7-day. And the expression in osteoclasts was more than that in osteoblasts or osteocyte at 7-day.

• Applied Microscopy
• /
• v.37 no.4
• /
• pp.231-238
• /
• 2007

Although the biological significance of the antennal sensillae to millipedes are widely understood, the structure and function of the antennal sensillae are still not clear and more precise analysis is required. Thus, this study initiate to reveal the fine structural characteristics of various sensory receptors on the antennae of millipede Oxidus gracilis were observed with field emission scanning electron microscopy(FESEM). The antennae generally include eight segments, called articles. On the surface of the antennae, there are a variety of sensory receptors which include olfactory and mechanical receptors. We could identify four different types of antennal sensillae in O. gracilis as follows: apical cone sensilla, trichoid sensilla, chatiform sensilla and basiconic sensilla. The most prominent is four large spital cone sensillae on distal tip of the 8th article. Both of trichoid and chaetiform sensillae are abundantly observed at the most of antennal articles. These sharply pointed structures are inclined and slightly curved toward the apex of the sensilla. The basiconic sensilla are further divided into three subtypes: large basiconic sensilla($Bs_1$), small basiconic sensilla($Bs_2$) and spiniform sensilla($Bs_3$). The $Bs_1$ is located at the 5th and 6th articles, while the $Bs_2\;and\;Bs_3 can be seen at the 5th and 7th articles, respectively.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.10
• /
• pp.79-88
• /
• 2012

Small amount of salt and various microorganisms are contained in natural soils or clays near the shore. In this study, most common clay minerals such as kaolinite and bentonite are used to evaluate the effect of salt and microorganism on liquid and plastic limits. The effect of time after mixing clays with water was also investigated for the consistency limits of clays. The test was conducted immediately, 1 day, or 7 days after mixing soils. For liquid limit tests two different test methods were used, the percussion cup method by Casagrande and the fall cone method. When sea water or microbial solution was used for mixing soils rather than distilled water, the liquid limit of kaolinite decreased by 6-15% and that of bentonite further decreased up to 37-53%. The liquid limit obtained from the fall cone method was approximately 10% for bentonite and 20% for kaolinite, which are higher than those from the percussion cup method. The effect of time on liquid and plastic limits was significant for those tested immediately or 1 day later but the values obtained after 1 day or 7 days did not vary a lot, regardless of soils, mixing waters or test methods.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.5
• /
• pp.2393-2398
• /
• 2012

Objectives: The purpose of this study was to evaluate the geometric accuracy of thoracic anatomic landmarks as target surrogates of intrapulmonary tumors for manual rigid registration during image-guided radiotherapy (IGRT). Methods: Kilovolt cone-beam computed tomography (CBCT) images acquired during IGRT for 29 lung cancer patients with 33 tumors, including 16 central and 17 peripheral lesions, were analyzed. We selected the "vertebrae", "carina", and "large bronchi" as the candidate surrogates for central targets, and the "vertebrae", "carina", and "ribs" as the candidate surrogates for peripheral lesions. Three to six pairs of small identifiable markers were noted in the tumors for the planning CT and Day 1 CBCT. The accuracy of the candidate surrogates was evaluated by comparing the distances of the corresponding markers after manual rigid matching based on the "tumor" and a particular surrogate. Differences between the surrogates were assessed using 1-way analysis of variance and post hoc least-significant-difference tests. Results: For central targets, the residual errors increased in the following ascending order: "tumor", "bronchi", "carina", and "vertebrae"; there was a significant difference between "tumor" and "vertebrae" (p = 0.010). For peripheral diseases, the residual errors increased in the following ascending order: "tumor", "rib", "vertebrae", and "carina"; There was a significant difference between "tumor" and "carina" (p = 0.005). Conclusions: The "bronchi" and "carina" are the optimal surrogates for central lung targets, while "rib" and "vertebrae" are the optimal surrogates for peripheral lung targets for manual matching of online and planned tumors.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.34 no.2
• /
• pp.303-317
• /
• 2010

This study helps in the production of brassieres suitable for female adults by researching the actual wearing conditions and purchasing status, satisfaction rate, and preferences of female college students in their early 20's. The collected data was analyzed by a SPSSWIN 13.0 Program and the results of the research are as follows. 1. There is a noticeable difference between the breast satisfaction rate and breast size, in addition the satisfactory rate was higher in the normal breast size or a little ample size than in the very small or very big size. According to the shape, the satisfactory rate for the breast appeared to be high in the case of the recognition and evaluation of the hemisphere type than the flat, cone, pop out, and downward type. 2. For fitness, the looseness at the top of the cup (pressed between the breasts at the upper part of the front middle), pressing and looseness at the upper sides of the cup, inappropriate size of the cup, tightness of the wings, tightness at the bottom round of the breasts, the narrow width of the wire, wide space of the shoulder strings, and the sliding of the shoulder strings had problems that needed improvement. 3. The major priorities for purchasing brassieres are size, fitness, and aesthetic qualities. As a result, the size and the fitness are more important than the trend or decorations since the brassiere has the function to support the breasts that shows that hygiene and sanitation are recognized as an important standard for undergarment selection. The size and the fitness are important factors regardless of breast types in the examination of the selection standards of the brassieres for each breast type, but the cone and hemisphere types have higher preferences for design; the pop out type has more considerations for the material of the cloth. The result show that appearance is more important for smaller breasts, but the functionality of the brassier is more important than the appearance for medium and larger breast sizes.

• Journal of the Korean GEO-environmental Society
• /
• v.14 no.7
• /
• pp.31-38
• /
• 2013

After debris flow caused damage during recent years, many scholars and engineers have thrown their effort into analyzing risk from debris flow in Korea. But it is hard to predict damage by debris flow taken place in wide area. Recently, SINMAP program is widely well used to estimate the amount of debris flow and its' range. In order to make frequent use of it, the most important thing is selection of accurate input parameters. In-situ experiments, which are avaliable in the mountain, is to be suggested to get dependable input parameters for SINMAP. Those are permeability, cohesion, density, friction angle and thickness in SINMAP. To get those, test pit, block sampling, in-situ density test, auger boring, permeability test on ground surface, borehole shear test and dynamic cone test and so forth were selected. In addition, the reliability of the results will be increased through comparing with those by laboratory tests. Hence, the experiments are hard to enter the sites without temporary road and, if possible, licensing and many times are needed, too. Small size experiments are indeed necessary to get accurate parameters.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.29 no.4
• /
• pp.418-425
• /
• 2013

This case report describes about recurrent herpetic stomatitis mimicking post-root resection complication. A 49 year-old male patient was diagnosed vertical root fracture of the mesiobuccal root of his left maxillary first molar (#26). The mesiobuccal root was resected following root canal treatment of the same tooth. 19 months later, the patient presented with pain on left hard palate after a barbecue party. Intra oral examination revealed a gum boil-like blister at the hard palate corresponding to the apex of the palatal root of #26. On clinical examination, there was bleeding on probing and the periodontal pocket depth was measured less than 5 mm with no tooth mobility. On a periapical radiograph, periodontal ligament space widening was observed. Tracing the sinus tract with gutta percha cone was attempted, however, it was impossible. Extending the field of vision, small multiple round ulcerations were observed at the palate front which caused pain to the patient. Therefore, the pain was considered a non odontogenic and the patient was referred to the department of oral medicine. The patient was diagnosed recurrent herpetic stomatitis and after 3 days of antiviral medication, the pain and ulceration were subsided.

• Advances in nano research
• /
• v.16 no.2
• /
• pp.127-140
• /
• 2024

Upon direct/indirect exposure to flame or heat, composite structures may burn or thermally buckle. This issue becomes more important in the natural fiber-based composite structures with higher flammability and lower mechanical properties. The main goal of the present study was to obtain an optimal eco-friendly composite system with low flammability and high thermal buckling resistance. The studied composite consisted of polypropylene (PP) and short abaca fiber (AF) with eggshell powder (ESP) and halloysite clay nanotubes (HNTs) additives. An optimal base composite, consisting of 30 wt.% AF and 70 wt.% PP, abbreviated as OAP, was initially introduced based on burning rate (BR) and the Young's modulus determined by horizontal burning test (HBT) and tensile test, respectively. The effects of adding ESP to the base composite were then investigated with the same experimental tests. The results indicated that though the BR significantly decreased with the increase of ESP content up to 6 wt.%, it had a very destructive influence on the stiffness of the composite. To compensate for the damaging effect of ESP, small amount of HNT was used. The performance of OAP composite with 6 wt.% ESP and 3 wt.% HNT (OAPEH) was explored by conducting HBT, cone calorimeter test (CCT) and tensile test. The experimental results indicated a 9~23 % reduction in almost all flammability parameters such as heat release rate (HRR), total heat released (THR), maximum average rate of heat emission (MARHE), total smoke released (TSR), total smoke production (TSP), and mass loss (ML) during combustion. Furthermore, the combination of 6 wt.% ESP and 3 wt.% HNT reduced the stiffness of OAP to an insignificant amount by maximum 3%. Moreover, the char residue analysis revealed the distinct differences in the formation of char between AF/PP and AF/PP/ESP/HNT composites. Afterward, dilatometry test was carried out to examine the coefficient of thermal expansion (CTE) of OAP and OAPEH samples. The obtained results showed that the CTE of OAPEH composite was about 18% less than that of OAP. Finally, a theoretical model was used based on first-order shear deformation theory (FSDT) to predict the critical bucking temperatures of the OAP and OAPEH composite plates. It was shown that in the absence of mechanical load, the critical buckling temperatures of OAPEH composite plates were higher than those of OAP composites, such that the difference between the buckling temperatures increased with the increase of thickness. On the contrary, the positive effect of CTE reduction on the buckling temperature decreased by raising the axial compressive mechanical load on the composite plates which can be assigned to the reduction of stiffness after the incorporation of ESP. The results of present study generally stated that a suitable combination of AF, PP, ESP, and HNT can result in a relatively optimal and environmentally friendly composite with proper flame and thermal buckling resistance with no significant decline in the stiffness.