• 한국주조공학회지
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• 제15권5호
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• pp.494-506
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• 1995

Test castings in plate, disc, and cubic shaped castings for 0.2wt.% carbon and stainless steel have been poured to examine the effects of the riser dimensions including riser neck on the casting soundness. Three empirical methods were chosen in risering of steel castings. A computer program of solidification analysis considering liquid and solidification contraction was developed to apply for riserdesign calculated by using their methods in plate, disc, and cubic shaped castings, and to calculate the position and dimension of shrinkage cavity in complex shaped casting. The potential of present method has been successfully demonstrated by comparing predicted cavity shapes with those obtained in a series of experimental castings. Three empirical methods can be used in a practical way to make a rapid estimation of tie minimum riser diameter, but they can not provide a criterion of casting soundness with shape and material on all occasions. The shape and position of shrinkage cavity can be successfully predicted both using the present method and using risering calculated by their methods regardless of the shape and cast material.

• Imaging Science in Dentistry
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• 제49권2호
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• pp.103-113
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• 2019

Purpose: Anatomical variations of the external nasal wall are highly important, since they play a role in obstruction or drainage of the ostiomeatal complex and ventilation and can consequently elevate the risk of pathological sinus conditions. This study aimed to assess anatomical variations of the nasal cavity and ethmoidal sinuses and their correlations on cone-beam computed tomography (CBCT) scans. Materials and Methods: This cross-sectional study evaluated CBCT scans of 250 patients, including 107 males and 143 females, to determine the prevalence of anatomical variations of the nasal cavity and ethmoidal sinuses. All images were taken using a New Tom 3G scanner. Data were analyzed using the chi-square test, Kruskal-Wallis test, and the Mann-Whitney test. Results: The most common anatomical variations were found to be nasal septal deviation (90.4%), agger nasi air cell (53.6%), superior orbital cell(47.6%), pneumatized nasal septum(40%), and Onodi air cell(37.2%). Correlations were found between nasal septal deviation and the presence of a pneumatized nasal septum, nasal spur, and Haller cell. No significant associations were noted between the age or sex of patients and the presence of anatomical variations (P>0.05). Conclusion: Radiologists and surgeons must pay close attention to the anatomical variations of the sinonasal region in the preoperative assessment to prevent perioperative complications.

• Applied Microscopy
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• 제28권2호
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• pp.159-170
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• 1998

The glandular secretory system of the capitate gandular trichomes in leaf of Thymus quinquecostatus Celakovsky was examined by transmission electron microscope. The glandular trichome was consisted of three cell layers; an basal cell layer, a stalk cell with single-celled intermediate layer and a discoid secretory layer with thickened cuticle. The secretory cell was dense, rich in mitochondria, rER, plastds, Golgi complex and had many vesicular structure. Typical plastids with reticulate body and plastoglobule were present in glandular trichome. The tytoplasm of secretory cell was filled with osmiophilic secretory materials. The secretory vesicles, originated from Golgi complex, appeared as membrane bounded vesicles and secreted to the outer wall surface. The presences of well developed rER, mitochondria, Golgi complex, and membrane-bounded vesicles fused with plasmalemma in the secreting cells indicate that the granulocrine mechanism of secretion was occurring in T. quinquecostatus. Subcuticular cavity was developed between the cuticular layer and the secretory cell wall, and it formed above the secretory cell upon separation of cuticle-wall.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.82-86
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• 1993

Two crystal structures of dehydrated $Ag_{3.3}Ca_{4.35}-A ({\alpha} = 12.256(2){\AA})$ and of its ethylene sorption complex (${\alpha} = 12.259(2){\AA}$) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(l)$^{\circ}$C. Both crystals were dehydrated at 360$^{\circ}$C and $2{\times}10^{-6}$ Torr for 2 days and one crystal was treated with 200 Torr of ethylene at 24(2)$^{\circ}$C. The structures were refined to final error indices, $R_1$=O.065 and $R_2$ = 0.088 with 202 reflections and $R_1$=0.049 and $R_2$ = 0.044 with 259 reflections, respectively, for which I>3${\sigma}$(I). In these structures, all Ag$^+$ and Ca$^{2+}$ ions are located on two and three different threefold axes associated with 6-ring oxygens, respectively. In $Ag_{3.3}Ca_{4.35}-A{\cdot}6.65\;C_2H_4,\;3.3\;Ag^+\;and\;3.35\;Ca^{2+}$ ions are recessed 1.09 ${\AA}$ and 0.21 ${\AA}$, respectively, into the large cavity from the (111) plane at O(3). Each Ag$^+$ and Ca$^{2+}$ ion in the large cavity forms a complex with one $C_2H_4$$^{2+}$ ions and ethylene molecules are longer than those between Ag$^+$ ions and ethylene molecules.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.566-569
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• 2001

Researchers have invectigated nasal flow both numerically and experimentally for centuries. Experimental studies most have suffered from various limitations necessary to allow the measurements to be obtained with available equipment. Nasal airflow can be subdivided into two interrelated categories; nasal airflow resistance and heat and mass transfer between the air stream and the walls of the nasal cavity. In this study, thanks to a new method for model casting by a combination of Rapid prototyping and Solidification of clear silicone, a transparent rectangular box containing the complex nasal cavity is made for PIV experiments. The CBC PIV algorithm is used for analysis.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.967-971
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• 1998

KOMAC (KOrea Multi-purpose Accelerator Complex) is the 1 Gev, 20 ㎃ proton linac. The superconducting linac for the high energy part acceleration from 100 MeV to 1 GeV is selected as a main candidate. As is well known, the superconducting linac has advantages for high current, high energy acceleration such as a large bore size, short accelerator length, and the RF efficiency. In this energy, the velocity of proton increases from $\beta$=0.87. For the design and fabrication simplicity, the cavity $\beta$ stages are divided into 3 parts. The maximum electric field in the cavity is designed below 20 ㎹/m. In this paper the design concepts and guides for this superconducting linac are introduced.

• 한국결정학회지
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• 제10권1호
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• pp.66-70
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• 1999

The calix[4]arene molecule adopting the 1,3-alternate conformation forms a square cavity, and two pair phenyl rings lying above and below a least-square plane defined by the four bridging methylene groups in the calix[4]arene are widened upwards and downwards, respectively, from central axis, which leads to O1-O4=4.064 and O2-O3=3.864 . Two propyloxy groups are stabilized with all trans conformations, but the rather short azacrown ether chain with two oxygen atoms includes cis/trans conformations with O1-C35=2.906 . Therefore the cavity does not seem to be big enough to form a host-guest complex.

• KSBB Journal
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• 제13권1호
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• pp.26-30
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• 1998

The suspension cultures of Mentha piperita produce menthol which has very low solubility in water due to its hydrophobicity. This can be considered as a factor for its low production in the suspension suspension cultures. Cyclodextrin has the hydrophobic cavity inside the molecule in which menthol can be captured and allow to form a stable complex. The suspension culture of Mentha piperita showed 70% higher production enhancement in the medium containing 1.5%(w/v) $\beta$-cyclodextrin than the control. $\beta$-cyclodextrin had no adverse effect on the cell growth and showed the best result among $\alpha$-, $\beta$- and $\gamma$-cyclodextrins tested in terms of menthol production. We demonstrated that $\beta$-cyclodextrin can be used to enhance the production of menthol in the suspension cultures by capturing hydrophobic menthol into the cavity of cyclodextrin molecules.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2001년도 Proceedings of 2001 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.138-150
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• 2001

Researchers have investigated nasal flow both numerically and experimentally for centuries. Experimental studies most have suffered from various limitations necessary to allow the measurements to be obtained with available equipment. Nasal airflow can be subdivided into two interrelated categories; nasal airflow resistance and heat and mass transfer between the air stream and the walls of the nasal cavity. In this study, thanks to a new method for model casting by a combination of Rapid prototyping and curing of clear silicone, a transparent rectangular box containing the complex nasal cavity is made for PIV experiments. The CBC PIV algorithm is used for analysis. Average and RMS distributions are obtained for inspirational and expiration nasal airflows. Comparison between western and Korean nasal air flows are appreciated. Flow fields for Korean model shows some differences from western's. Flow resistances for breathing are measured with varying flow rates.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.298-302
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• 2002

Equivalent volume estimation of the coupler and two coupled microphones has a key role in standard microphone pressure calibration. The equivalent volume of the microphone is determined by the dynamic characteristics of the diaphragm system and front cavity. Therefore the modal parameters of diaphragm system - natural frequency and damping fatter - should be measured explicitly for the estimation of the equivalent volume. The diaphragm system is composed of the vibrating diaphragm, back slit behind diaphragm, pressure equalization vent, and front cavity which are acoustically coupled. In the measurement, the electrostatic actuator was used to excite the system with the swept sine, and the frequency response was obtained. The close actuator in front of the diaphragm must influence the radiation impedance of the system, and then the modal parameters. From the measured frequency response, the natural frequency and the damping factor could be estimated with the Complex exponential method based on the Prony model and the zero crossing real and imaginary plot.