• Journal of the Korean Ceramic Society
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• v.42 no.8 s.279
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• pp.525-531
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• 2005

Tailoring the microstructure and the composition of silicon nitride ceramics can have profound effects on their properties. Here it is shown that the grain growth behavior, in particular its anisotropy, is a function of the specific additives, which allow one to tune the microstructure from one consisting of more equiaxed grains to one with very elongated grains. Recent studies are discussed that provide an understanding of the atomic level processes by which these additives influence grain shapes. Next the microstructural (and compositional) parameters are discussed that can be used to modify the thermal conductivity, as well as fracture toughness of silicon nitride ceramics. As a result of the open <0001> channels in $\beta-Si_3N_4$, the c-axis conductivity can be exceptionally high. Thus, the formation of elongated c-axis grains, particularly when aligned can result in conductivity values approaching those of AlN ceramics. In addition, the controlled formation of elongated grains can also be used to significantly enhance the fracture toughness. At the same time, both properties are shown to be affected by the composition of the densification additives. Utilizing such understanding, one will be able to tailor the ceramics to achieve the properties desired for specific applications.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1129-1138
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• 1997

Al2O3/20 vol%YAG composite containing equiaxed grains and Al2O3/20 vol%LaAl11O18 composite containing elongated grains were fabricated using Al2O3-Y2O3 composition and Al2O3-La2O3 composition, respectively, by hot-pressing. In order to investigate the influence of microstructural control of second phase on toughening effect of toughened ceramic composites, AE (acoustic emission) measurements have been coupled with fracture toughness experiments(SENB and SEPB method). A separation of the fracture toughness and analysis of toughening mechanism was possible using the AE technique. The fracture toughness of hot-pressed materials was estimated to be 3.2 MPam0.5 for monolithic alumina, 4.7 MPam0.5 for Al2O3/20 vol%YAG composite and 6.2 MPam0.5 for Al2O3/20 vol%LaAl11O18 composite. In monolithic Al2O3, toughening does not occur as a result of either microcracking or grain bridging, whereas, composites exhibit toughening effects by both microcracking in the frontal zone and gain bridging in the wake zone, resulting in an improvement of fracture toughness as compared with monolithic Al2O3. The fracture toughness of Al2O3/20 vol%LaAl11O18 composite is higher than that of Al2O3/20 vol%YAG composite. It may be attributed to the elongated microstructure of Al2O3/20 vol%LaAl11O18 composite, resulting relatively greater bridging effect.

• Korean Journal of Plant Tissue Culture
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• v.22 no.2
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• pp.101-104
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• 1995

The experiment was conducted to identify the optimal in vitro propagation condition for P. lactiflora Pall. Through apical shoot tip and axillary shoot tip culture of winter bud. When apical shoot tip and axillary shoot tips excised from winter bud were cultured on MS medium supplemented with various concentrations of plant growth regulators, all the apical shoot tips elongated regardless of the composition of the medium but axillary shoot tips responded differently. Shoot of 'Uisong' local cultivate was well elongated in the medium containing 0.01mg/L NAA. Frequency of shoot formation and subsequent shoot growth in axillary shoot tip culture were promoted in the medium containing 0.01 mg/L NAA and 5.0mg/L zeatin. 30% of the elongated shoots were vigorously rooted on the medium containing 0.1mg/L NAA with vermiculite as a support medium.

• Korean Journal of Ichthyology
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• v.25 no.2
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• pp.74-81
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• 2013

Factors influencing spawning or respawning conditions of the bitterling, Acheilognathus signifer were investigated in the aquariums. Inducing the female spawning was more sensitive to the mussel than the male. The ovipositor of the female was periodically elongated and reduced from 4 to 6 days with the presence of mussel. During of the elongated state of the ovipositor was 1 to 2 days. As the result of natural spawning in the aquariums, it takes 1 to 3 days (mean 1.6) to spawn. The most important factor to respawn spawned females again was the mussel. It takes 11 to 53 days (mean 29.5) from extraction to reextraction of females which have elongated ovipositor. The egg numbers of reextraction were 2 to 41 (mean 19). This experiments showed the tendency the more standard length of females grows, the more the number of extracted eggs increases.

• Journal of Oral Medicine and Pain
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• v.43 no.3
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• pp.77-83
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• 2018

Purpose: The present study was designed to investigate the association of ponticulus posticus (PP) and elongated styloid process (ESP) with headaches. Methods: Analysis of head and neck cone beam computed tomography samples from the archives of the Department of Oral Radiology was done for the presence of partial or complete PP and ESP length, type, thickness, mediolateral angulation, anterioposterior angulation (horizontal & vertical), lateral or medial curvature. This was followed by personal & telephonic questionnaires to the subjects for the evaluation of the presence of headaches & other associated symptoms. Results: Among 134 subjects, 62 subjects (46.3%) presented with headache and 72 subjects (53.7%) did not have any headache. On further analysing the total 62 subjects with headache, it was found out that 31 subjects (50.0%) of them had ESP and PP both, 16 subjects (25.8%) had only ESP, and 15 subjects (24.2%) had only PP. A strong association was present between headache and presence of PP & ESP individually and together. Conclusions: All health care professionals dealing with the head and neck pain disorders should also consider the presence of ESP & PP during diagnosis and treatment.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.3
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• pp.157-162
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• 2023

Elongated styloid syndrome (ESS) can present with myriad symptoms that mimic common features of orofacial pain, such as temporomandibular joint disorders (TMJDs), often causing a challenge and delay in diagnosis. We report the case of a 52-year-old male with a three-year history of non-painful clicking during jaw movement initially diagnosed as TMJD-related internal derangement. The patient presented with a history of annoying jaw sounds for three years, described as a popping sound without bilateral clicking or crepitation. Tinnitus and progressive hearing loss were observed in the right ear, and a hearing aid was recommended by an otolaryngologist. The patient was initially diagnosed with TMJD and managed accordingly; nevertheless, his symptoms persisted. Imaging revealed prominent bilateral styloid process elongation that exceeded the recognized cut-off level of >30 mm for elongation. The patient was informed of his diagnosis and its treatment but opted only for further swallowing and auditory assessments of his ear and nose symptoms. Clinicians should consider including ESS as a differential diagnosis in patients presenting with non-specific chronic orofacial symptoms for timely diagnosis and favorable clinical outcomes.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.435-442
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• 2004

We obtained precise linear transverse displacements from the results of signal processing on moire fringes measured by the superposition of a fixed self-imaging elongated circular(EC) grating and a moved EC grating. The linear displacement less than one pitch of the moving EC grating was calculated from the position of a bright moire fringe generated on the linear grating part of the EC gratings. The moire signals were high-frequency-filtered, smoothed, curve-fitted, and first-differentiated moire signals in sequence. Also the linear displacement created by movement by the unit of integer times of a pitch was readily measured by the count of the even number of zero-crossing points corresponding to bright moire fringes obtained by the above same processing without curve fitting. Then we can measure linear transverse displacements with the accuracy of better than 3 %, which are more accurate values than those by the traditional visual method within the displacement of 80 ${\mu}{\textrm}{m}$.

• The Korean Journal of Zoology
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• v.8 no.1
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• pp.1-7
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• 1965

The short-necked clam is distributed widely in Korean tidal flats and it is a much an important bivalve quantitatively as to control the production of the tidal flat. The shell of this clam tends to show remarkable morphological variations depending on the habitat. Under a seemingly favorable condition for the growth , the color pattern of shell of the clam is clear and obvious and having less weight and elongated shape, the ratios of shell length to both height and width are small . On the contrary , when the environment appears to be an unfavorable one, the shell is found to be heavy and stunted with smudgy color pattern. If this correlation between could be a basis for the judgement in suitability of growth environment for the clam. In the Ikawazu Bay, Japan, it is revealed that the elongated shell is produced from the coast outside of the Bay (1) , the stunted from the esturay (2) and the intermediate from the floodgate area (3) and the middle of the Bay (4). Followings are the results obtained from the morphological investigation of the claim in this Bay. 1. Relationship between the shell length and the largest shell rib length is linear and between the shell length and the shell width is also linear but with a critical point at the shell length of 17-20 mm. The ratio between the width and the largest rib length at a given shell length increases with the order of 1, 3, 4, and 2. 2. A gradual decreases of the ratio of the shell length to the largest rib length is observed when the former is less than 17-18 mm, and this ratio increases with the shell of longer. Also there is a different range of this ratio in each different location ; the greatest range in 2, the smallest in 1 and 4 being in between. 3. A similar biometric finding is apparent with the ratio between the length and width of the shell and the order in value is 2, 4, 1 and 3. 4. The ratios between the length and the largest rib length of elongated and stunted shell are 0.84-0.86 and 0.89-0.92, respectively , and those between the length and width are 0.40-0.51 and 0.49-0.58, respectively. 5. Generally , the elongated short necked clam shells are products of the tidal flat of good circulation of sea water with high salinity and smaller fluctuations of salinity and temperature within a day. The stunted shells are produced for tidal flats of opposite of above conditions.

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.05a
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• pp.101-102
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• 1993

• Parasites, Hosts and Diseases
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• v.21 no.1
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• pp.75-82
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• 1983

An electron microscopic study was performed to know the basic tegumental structure of Cysticercus cellulosae. The scolex and bladder portions of cysticerci (human and porcine strains) were prepared for transmission and scanning electron microscopy by conventional procedures. In general, the tegument of C. cellulosae showed the basic ultrastructure of cestode tegument on electron micrographs. The teguments of both scolex and bladder portions consisted of such components, i.e., an outer vesicular layer with numerous microtriches and inner filroug layer. Below the fibrous layer, there were layers of muscle bundles and tegumental cells. The microtriches which covered the surface of cysticercus revealed two distinctly different shapes. The characteristic bladder-like, elongated pyramid shaped "tetrahedrial form" was observed on the surface of the scolex portion, whereas the elongated cylindrical "filamentous form" was distributed on the stirface of bladder portion. In spite of the difference of isolated host and location, the cysticerci showed tole same result. But dimensional variations of the tegument according to topography of the worm were observed. The possibility of application in making differential diagnosis from other larval cestodes and possible functions of this larval tegument were discussed.