• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.33-41
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• 2014

In a supersonic turbine, A rotor overlap technique reduced the chance of chocking in the rotor passage, and made the design pressure ratio satisfied. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, an approximate optimization technique was appled to find the optimal shape of overlap which maximizes the improvement of the turbine performance. The design variables were shape factors of a rotor overlap. An optimal design for rotor overlap reduces leakage mass flow rate at tip clearance by about 50% and increases about 4% of total-static efficiency compared with the base model. It was found that the most effective design variable is the tip overlap and that the hub overlap size is the lowest.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.32-41
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• 2009

In this study, scale-down design of full-scale Korean Utility Helicopter (KUH) main rotor blade has been investigated. The scaled model system were designed for the measurement of aerodynamic performance, tip vortex and noise source. For the purpose of considering the same aerodynamic loads, the Mach-scale method has been applied. The Mach-scaled model has the same tip Mach number, and it also has the same normalized frequencies. That is, the Mach-scaled model is analogous to full-scale model in the view point of aerodynamics and structural dynamics. Aerodynamic scale-down process could be completed just by adjusting scaling dimensions and increasing rotating speed. In the field of structural dynamics, design process could be finished by confirming the rotating frequencies of the designed blade with the stiffness and inertial properties distributions produced by sectional design. In this study, small-scaled blade sectional design were performed by applying domestic composite prepregs and structural dynamic characteristics of designed model has been investigated.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.66.3-67
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• 2016

The Giant Magellan Telescope (GMT) will feature two interchangeable Gregorian secondary mirrors, an adaptive secondary mirror (ASM) and a fast-steering secondary mirror (FSM). The FSM has an effective diameter of 3.2 m and built as seven 1.1 m diameter circular segments, which are conjugated 1:1 to the seven 8.4m segments of the primary. Each FSM segment contains a tip-tilt capability for fine co-alignment of the telescope subapertures and fast guiding to attenuate telescope wind shake and mount control jitter. This tip-tilt capability thus enhances performance of the telescope in the seeing limited observation mode. As the first stage of the FSM development, KASI conducted a Phase 0 study to develop a program plan detailing the design and manufacturing process for the seven FSM segments. The GMTO-KASI team matured this plan via an internal review in May 2016 and the revised plan was further assessed by an external review in June 2016. In this poster, we present the technical aspects of the FSM development plan.

• International Journal of Fluid Machinery and Systems
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• v.5 no.2
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• pp.65-71
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• 2012

The objective of the present investigation is to explore the possibility of improving the performance of a centrifugal fan at low Reynolds numbers using a simple passive means, namely Gurney flap (GF). GFs of 1/$8^{th}$ inch brass angle (3.175 mm) corresponding to 15.9% of blade exit height or 5.1% of blade spacing at the impeller tip are attached to the impeller blade tip on the pressure surface. Performance tests are carried out on the centrifugal fan with vaneless diffuser at five Reynolds numbers (viz., 0.30, 0.41, 0.55, 0.69, $0.82{\times}10^5$, i.e., at five speeds respectively at 1,100, 1,500, 2,000, 2,500 and 3,000 rpm) without and with GF. Static pressures on the vaneless diffuser hub and shroud are also measured for each speed at four flow coefficients [${\phi}$=0.23 (below design flow coefficient), ${\phi}$=0.34 (design flow coefficient), ${\phi}$=0.45 (above design flow coefficient) and ${\phi}$=0.60 (above design flow coefficient)] with and without GF. From the performance curves it is found that the performance of the fan improves considerably with GFs at lower Reynolds numbers and improves marginally at higher Reynolds number. Similar improvements are observed for the static pressures on the diffuser hub and shroud. The effect of Reynolds number on the performance and static pressures is considerable. However the effect is reduced with GFs.

• Archives of Craniofacial Surgery
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• v.18 no.4
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• pp.243-248
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• 2017

Background: To evaluate the versatility and reach of modified nasolabial flap used in reconstruction of defects created in and around the oral cavity. Methods: A total number of 20 cases were selected. Out of which 13 were males and 7 females. The age of these patients ranged from 24-63 years. 29 modified nasolabial flaps were raised in twenty patients. Based on clinical and histopathological examination, out of 20 patients, 14 patients were diagnosed with oral submucous fibrosis, 3 with verrucous carcinoma, 1 with squamous papilloma, 1 with oro-antral fistula and 1 with traumatic loss of lower lip. Results: Minimum preoperative interincisal distance (IID) was 0 mm and maximum was 15 mm with mean of $6.00{\pm}4.76mm$ in patients with oral submucous fibrosis and 12 months postoperatively minimum IID was 16 mm and maximum was 41 mm with mean of $28.00{\pm}8.96mm$. In one case, dehiscence (3.4%) was noted on the anterior tip for which tip revision was done. Bulky appearance of the flap intraorally was observed in 2 cases (6.9%). Five (17.2%) among the 29 flaps had visible scar at the donor site postoperatively up to 3 months. Conclusion: Numerous reconstructive techniques have been employed in the reconstruction of small to intermediate sized defects of oral cavity. Modified nasolabial flap is a versatile flap which has robust vascularity and can be successfully used with minimal complications. It can be rotated intraorally to extend from the soft palate to the lip. Thus, it can be used efficiently to treat the small defects of the oral cavity as well as recreating lost lip structure.

• Korean Journal of Ichthyology
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• v.28 no.2
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• pp.116-120
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• 2016

A specimen of Cocotropus masudai (41.2 mm in standard length), belonging to the family Aploactinidae, was firstly collected from the eastern coastal waters of Jejudo Island, Korea by using a fish trap in July 2011. This species is characterized by having the following morphological traits: XII, 9 dorsal fin rays; I, 8 anal fin rays; 12 pectoral fin rays; I, 3 pelvic fin rays; five preopecular spines; five sensory pores present on lower jaw and isthmus tip beyond fifth sensory pore. This species is similar to C. izuensis except for the number of preopercular spines (five in C. izuensis vs. four in C. masudai) and the anterior position of the isthmus (well beyond the fifth lower jaw sensory pore vs. the tip mostly reaching to the pore). In Korea, C. masudai can be easily distinguished from the Erisphex pottii in having the dorsal fin with nine soft rays (vs. 10~14 for Erisphex pottii), anal fin with seven soft rays (vs. 10~13) and pelvic fin with three soft rays (vs. two). We propose new Korean names, "Dot-chi-sok" and "Dot-chi" for the genus and species, respectively.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.344-350
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• 2007

Laryngo-tracheal perforation caused by the use of a stylet during tracheal intubation is a rare complication. We present a case of subcutaneous emphysema and connective tissue inflammation after tracheal intubation. The patient was a 41-year-old male undergoing general anesthesia for an appendectomy. The intubation was difficult during laryngoscopy (Cormack- Lehane Grade III). An assistant provided an endotracheal tube with a stylet inside while the laryngoscope was in place. During intubation, a short, dull sound was heard with a sudden loss of resistance after the distal tip of the endotracheal tube passed the rima glottis. A sonogram and computerized tomography revealed subcutaneous emphysema from the neck to the upper mediastinum and fluid collection between the trachea and the thyroid. This lesion appeared to have been caused by the protruded, loose stylet. Anesthesiologists should be aware of the damage a loose stylet protruding beyond the tip of the endotracheal tube can cause.

• Archives of Craniofacial Surgery
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• v.10 no.2
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• pp.61-66
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• 2009

Purpose: The aim of this study is to establish anatomical dimension of the nose and nostril shape in Korean twenties. Methods: Authors measured anthropometry of nose in Korean youths 1,000 individuals (male 363, female 637) and analyzed stastically them. Results: The mean measurements are as follows. 1. The shape of nostrils was classified into 7 types by the angle between both long axis of nostril (male / female). Type I ($<40^{\circ}$)1.7% / 1.72%, Type II ($41-70^{\circ}$) 26.17% / 29.35%, Type III ($71-100^{\circ}$) 39.94% / 38.77%, Type IV (unclassified) 3.85% / 5.80%, Type V ($101-130^{\circ}$) 20.93% / 17.89%, Type VI ($131-180^{\circ}$) 7.43% / 5.96%, Type VII ($>180^{\circ}$) 0% / 0.47% 2. Lengths (male/female) Width of nasal root: $25.29{\pm}2.25mm/24.72{\pm}2.40mm$ Width of nose: $37.63{\pm}2.46mm/34.77{\pm}2.11mm$ Width of columella: $7.18{\pm}0.92mm/6.92{\pm}0.86mm$ Width of alar: $4.99{\pm}1.00mm/4.74{\pm}0.91mm$ Width of nostril floor: $10.98{\pm}1.40mm/10.13{\pm}1.73mm$ Protrusion of nasal tip: $17.12{\pm}1.95mm/16.88{\pm}1.84mm$ Length of alar: $27.10{\pm}2.21mm/24.66{\pm}2.18mm$ Length of nasal root: $17.37{\pm}2.51mm/16.08{\pm}2.90mm$ Depth of nasal root: $7.83{\pm}1.63mm/6.82{\pm}1.36mm$ Length of columella: $8.13{\pm}1.40mm/7.30{\pm}1.46mm$ Height of nose: $60.50{\pm}8.90mm/59.14{\pm}9.22mm$ Height of nasal bridge: $52.68{\pm}7.49mm/50.57{\pm}7.71mm$ 3. Angles Nasofacial angle: $30.19{\pm}3.43^{\circ}/29.13{\pm}6.31^{\circ}$ Nasofrontal angle: $134.88{\pm}7.25^{\circ}/139.94{\pm}6.33^{\circ}$ Nasolabial angle: $95.08{\pm}8.95^{\circ}/95.80{\pm}8.93^{\circ}$ 4. Nasal index: $72.60{\pm}9.57%/68.21{\pm}7.03%$ Nasal tip protrusion-nasal height index: $45.64{\pm}5.21%/47.09{\pm}5.21%$ Nasal tip protrusion-nasal width index: $32.61{\pm}6.83%/31.63{\pm}6.71%$ Conclusion: These data could be useful reference for anthropometry of nose in Korean twenties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.482-488
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• 1996

The experiment was carried out to the find variation of the sugar contents in the tip and basal part of the cotyledon and remaining portion of embryos in Phaseolus vulgahs seeds during germination with HPLC analysis method. Water content in cotyledon of kidney bean seed was about 6.4~6.5 of fresh weight and incresed to 45.8~71.2% during germination showing that tip part of cotyledon has more water content by 1.1~3.8% compared to the lower part of it. Higher water onten was observed in the rest parts of the seed except cotyledon such as plumule, radicle and hypocotyl showing that it increased to 72.2~93.3% depending on the different tissue organs. Main important sugars in kidney seeds during germination stages are; raffinose, sucrose, glucose and fructose, and the amount are differed with the kinds of embryo in kidney bean seed organs and stages of germination. Raffinose amount in kidney bean is increasing repeatly when seeds become wet but disappear it soon after seed have germinated especially in growing embryo parts. Raffinose in basal parts of cotyledons were still presented some an amount after germination. Sucrose is synthesized highly in plumule embryo at the beginning stage of germination but disappeared it from 5 days after seeding stages. Amount of sucrose in cotyledon of kidney seeds and seedlings increased continuously after germination. The amount of glucose and fructose in the cotyledons of kidney seeds during germination varied 5~10% or 5~15% but in the germinating and growing organs, plumule, they increased continuously after germination.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.5
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• pp.33-41
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• 2001

The digital iron using ${\mu}$ processor is designed and compared experimentally with the conventional analog Iron. Designed digital iron shows two improved temperature control characteristics. First, the reduction of the difference error between the user setting temperature and the real temperature of the iron tip is examined. When the iron temperature is set to $200[^{\circ}C]$, $300[^{\circ}C]$, $400[^{\circ}C]$, $480[^{\circ}C]$ at the environmental temperatures of $-5[^{\circ}C]$ and $25[^{\circ}C]$, it is examined that the tip temperature is very stable and its error is within ${\pm}1.8[^{\circ}C]$. Second, it is conformed that the temperature fluctuation of the iron due to the soldering is reduced manifestly. When the temperature of iron tip is varied from $200[^{\circ}C]$ to $480[^{\circ}C]$ with 1[g] solder, the temperature errors of the analog iron are measured to be from $6[^{\circ}C]$ to $10[^{\circ}C]$. In case of designed digital iron, however, these errors are much smaller and they are from $2[^{\circ}C]$ to $5[^{\circ}C]$.