• Journal of ILASS-Korea
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• v.17 no.4
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• pp.171-177
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• 2012

To understand oxygenated fuel characteristics including spray penetration length and spray angle at a real engine ambient pressure condition, DME was injected into a high pressure chamber by a piezo injector common rail system. The piezo injector common rail system was able to apply steady injection pressure, rapid response, and accurate injection quantity. Injection and ambient pressure were varied to confirm a relation with spray form. Using a direct photographing technique, development process of DME spray was captured. DME injection quantity was enlarged linearly as increasing of the injection pressure. In the high pressure chamber, when the injection pressure was enlarged the penetration length and velocity were increased due to a big momentum of fuel particle at the same ambient pressure. When ambient pressure was increased, the DME spray penetration length and velocity were decreased since the high ambient density of nitrogen was acted as a resistance. Although the ambient pressure and injection pressure were varied, each case of spray angle was almost same since the spray angle had a connection of the injector nozzle geometry.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1139-1145
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• 2011

An automated anastomotic ring-pin system consisting of both the anastomotic ring-pin system and the coupler device has eliminated the drawbacks of the suture method. High density polyethylene (HDPE), a material with outstanding biocompatibility and injection molding capability, was used in the ring. SUS316 stainless steel, Ti-6Al-4Nb, Ti-6Al-4V, and unalloyed titanium were used in FEM simulations of the micropin. The authors categorized the microvascular anastomotic ring micropins into short neck (SN) and long neck (LN) groups in order to evaluate the effect of the micropin's fillet radius and neck length on the von Mises stress. The micropins were further divided into those with and without fillet. On the basis of the fillet radius rate (FRR), which represents the rate of change in the von Mises stress with respect to the availability and shape of the fillet, and the neck length rate (NLR), which represents the rate of change in the von Mises stress with respect to changes in the length of the neck within the fillet shape, it can be concluded that the SN-3 neck design is the most stable.

• Journal of Convergence for Information Technology
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• v.10 no.11
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• pp.296-301
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• 2020

The purpose of this study was to verify the efficacy of cosmetics containing peptides as a cosmetic method for eyelashes. The study subjects were 21 women aged 20 years, set as the experimental group (right eyelash) and the control group (left eyelash), and measured changes according to the use of peptide cosmetics for 4 weeks. As a result of the analysis, the change in the length and density of eyelashes showed significant differences in the interaction between the group and the experiment period, and in the main effect according to each experiment period (p<.001). In the change of eyelash density and thickness, it was found that there was a significant difference at week 3 and week 4 in the difference between groups by measurement period (p>.05, p>.01). Cosmetics containing peptides have been effectively proven to be an effective cosmetic method for safe and beautiful eyelashes by increasing the length and number of eyelashes to those who suffer from side effects caused by cosmetic procedures. In the future, we look forward to expanding research to a wide range of age groups.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.170-174
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• 2024

A laser beam propagating in free space can be negatively affected by atmospheric turbulence. To overcome this and correct the wavefront error of the laser beam itself, a deformable mirror (DM), which is a key component of adaptive optics, is widely used. In this paper, a novel precision assembling method is suggested for a multi-channel high-density DM. The material of the mirror sheet of the DM is silicon carbide (SiC), and the actuator is a stacked-type lead-magnesium-niobate (Pb(Mg_1/3Nb_2/3)O₃; PMN). To connect the mirror sheet and each actuator, a flexure is inserted. The flexure can make the DM operate with full strokes without the failure of adhesive. A series of jigs were designed and applied in order to assemble these three parts (the mirror sheet, actuators, and flexures) precisely. After assembly, the performance of the DM was also checked.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.369-374
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• 2000

In order to investigate the effects of addition of 1M sulfuric acid to the etching solution or 1M hydrochloric acid on the etching behavior of aluminum foil for electrolytic capacitors, the changes in the density of etch pit, the length and diameter of etch tunnels and the capacitance were analyzed using SEM, TEM, LCR meter etc. Sulfate ion as a corrosion inhibitor was contributed to the increase of the surface area comparing with chloride ion. By adding sul-furic acid the density of etch pit and the length of etched tunnel increased and the diameter of the tunnel decreased, resulting in the increase of capacitance. It was also shown that the capacitance decreased when the current density was below $0.9A/\textrm{cm}^2$, while remarkably increased in the other case.

• International Journal of Costume and Fashion
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• v.8 no.1
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• pp.36-52
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• 2008

Writer Hong Myung-hee, author of the novel Im Kkeok Jeong, provided an excellent description of the costume customs of the Chosun era, based on an understanding of various historical texts and literature by practical science proponents, and experience gained from the Hong household of Pungsan, a noble family of high standing during the Chosun dynasty. However, there is a tendency towards descriptions of late Chosun era customs, rather than 16th century customs, with the intent of heightening the image of what most people felt to represent Chosun and its prestige, thereby generating greater reader sympathy. Therefore, information on the costume customs of the novel 1m Kkeok Jeong is analyzed and re-formed to fit with the temporal setting of the 16th century. By providing data to aid visual understanding and re-creation, the intent is to accept it as material for the rumination of our ancestors and their lifestyles in the 16th century. The novel provides a good description of Chosun economic customs, in which cotton and hemp were used not only as fabric for clothes, but also as currency. The trade value of cotton drapery or hemp drapery with dimensions of 5 strand density at a length of 35 ja per roll was designated as 5 mal (about 90 liters) of rice by national law, but the actual value varied depending on the production of rice. Also, it is possible to confirm the existence of sang po with dimensions of 3 strand density at a length of 30 ja per roll, or 2 strand density seochongdae cotton, which was used only as currency due to the rough quality. Characteristics of the Chosun dynasty, a class-based society, are described through distinctions of attire. The writer's intent regarding the symbolic nature of attire reflecting social position, a characteristic of the entire Chosun period, is analyzed with the presentation of visual material.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.304-308
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• 2007

In order to find out the optimum fertilizer level and planting density of high yielding variety, $Okayma^{#2}$, this experiment was conducted with 3 compositions of fertilizer levels and a different plant density at the experiment paddy field of mat rush in Mokpo Experiment Station, National Institute of Crop Science, RDA. $Okayma^{#2}$, mat rush variety was grown under different fertilizer level and planting density with the highest yielding. Yield components such as stem length, number of stem were highest at the plots with fertilizer level (kg/10a), 80-20-40 and planting density, 20 ${\times}$ 10cm. Judging from the results reported above, at optimum fertilizer level and planting density of mat rush seemed to be 80-20-40kg/10a fertilizer and 20cm row spacing and l0cm or I5cm planting spacing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.35-40
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• 2006

The combustion instability in a model dump combustor with an exhaust nozzle and the possibility of combustion control using a loudspeaker to these instabilities were studied. By changing inlet velocity, combustor length and equivalence ratio, dynamic pressure signals and flame structures were simultaneously taken. Because inlet velocity and combustor length affect the life time of vortex in the dump combustor, the results showed that as the combustor length increased and the inlet velocity decreased, the instability frequency decreased and the maximum power spectral density of the dynamic pressure generally decreased. Also, instability frequency and maximum power spectral density of the dynamic pressure increased with the increment of equivalence ratio. From the data of close-loop control, the optimum time-delay control using a loudspeaker was confirmed to be able to reduce the vortex shedding induced from the mixed acoustic-convective mode combustion instability.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.323-337
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• 2018

Merkusii pine wood (Pinus merkusii) was extensively planted throughout Indonesia, where it is only indigenous in northern Sumatera, by the Dutch during colonial times. The demand for this wood species, especially in the domestic market, has increased notably, despite its limited durability regarding decay resistance. The purpose of this study was to investigate the occurrence of juvenile and mature wood on merkusii pine and to analyze its radial features from pith to bark based on density, shrinkage, static bending in modulus of rupture and modulus of elasticity, fiber length, microfibril angle, and durability. A segmented modeling approach was used to find the juvenile-mature transition. The graveyard test was performed to characterize the termite resistance from pith to bark of merkusii pine. The maturations were estimated to start at radial increments of 15 cm from the pith by fiber length and of 12 cm from the pith by microfibril angle. The projected figures for the proportion of juvenile wood at breast height were around 65%. The results also indicate that the pine wood was $0.52g/cm^3$ in density, 1.45 in coefficient of anisotropy, which indicates its good stability, 7597 MPa in modulus of elasticity, and 63 MPa in modulus of rupture. Natural durability against subterranean termite of the merkusii pine wood was rated to be grade 4 to 0 from pith to bark. However, after being treated by Entiblu and Enborer preservatives, its rating increased to grade 10 to 9.

• Journal of Sericultural and Entomological Science
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• v.44 no.1
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• pp.13-18
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• 2002

The morphorogical characteristics of the Morus tiliaefolia growing wild in the Korean peninsula are as follows. The chromosome number of somatic cell is 2n=84,that is hexaploid. The shape of male inflorescence is a long cylinder shape of 3.6∼6.0 cm. The length of female inflorescence is 1.8 cm, red violet or violet and the weight of mulberry fruits is 1.39∼1.65 g. The winter bud is very big in comparison with the branch and the accessory bud does not exist. The leaf is big and lobed leaf or entire leaf, the density of lenticell is 9.42$\pm$1.29 ㎠. The length of leaf trichome is 236∼438 ㎛ and the distribution density is 16∼37/25 ㎟ and heigh density of leaf back. The trichome shape of the leaf surface is cylinder shaped, in the leaf back it is thin and long corn shaped.