• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.415-420
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• 2019

To investigate the effect of nonionic surfactant and emulsion stabilizer on O/W emulsions, various emulsion formulations with different types of nonionic surfactants and emulsion stabilizers were prepared and their rheological properties were compared. In this study, polysorbate 60 (Tween 60), PEG-60 hydrogenated castor oil (HCO 60), octyldodeceth-16 (OD 16), and ceteareth-6 olivate (Olivem 800) were used as hydrophilic nonionic surfactants, whereas cetyl alcohol, glyceryl monostearate, and stearic acid as emulsion stabilizers. Phase separation occurred only in the emulsion formulation with octyldodeceth-16 and all other emulsion formulations maintained a stable phase. The viscosity, hardness, and creaminess of emulsion formulation using a mixture of ceteareth-6 olivate and cetyl alcohol were the highest, and the emulsified droplet size was also the largest. These results are due to the formation of a network structure texture with the development of a large amount of liquid crystal in the O/W emulsion. In this formulation, the value of elastic modulus was large and the thixotropic behavior, in which the viscosity varies with the history of external force, was observed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.24-30
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• 2018

Dental implants are currently widely used as artificial teeth due to their good chewing performance and long life cycle. A dental implant consists of an abutment as the upper part and a fixture as the lower part. When chewing forces are repeatedly applied to a dental implant, gap at the interface surface between the abutment and the fixture is often occurred, and results in some deteriorations such as loosening of fastening screw, dental retraction and fixture fracture. To cope with such problems, a sealing-type abutment having a number of grooves along the conical-surface circumference was previously developed, and shows better sealing performance than the conventional one. This study carries out optimization of the groove shape by genetic algorithm(GA) as well as structural analysis in consideration of external chewing force and pretension between the abutment and the fixture. The overall optimization system consists of two subsystems; the one is the genetic algorithm with MATLAB, and the other is the structural analysis with ANSYS. Two subsystems transmit and receive the relevant data with each other throughout the optimization processes. The optimization result is then compared with that of the conventional one with respect to the contact pressure and the maximum stress. The result shows that the optimized model gives better sealing performance than the conventional sealing abutment.

• Korean Journal of Applied Biomechanics
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• v.28 no.4
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• pp.213-218
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• 2018

Objective: The purpose of this study was to examine the effect of the core muscle strength enhancement of the elderly on 8 weeks training using the core exercise equipment for the elderly on the ability to control the whole-body center of mass in posture stabilization. Method: 16 females (10 exercise group, 6 control group) participated in this study. Exercise group took part in the core strength training program for 8 weeks with total of 16 repetitions (2 repetitions per week) using a training device. External perturbation during standing as pulling force applied at the pelvic level in the anterior direction was provided to the subject. In a UCM model, the controller selects within the space of elemental variables a subspace (a manifold, UCM) corresponding to a value of a performance variable that needs to be stabilized. In the present study, we were interested in how movements of the individual segment center of mass (elemental variables) affect the whole-body center of mass (the performance variable) during balance control. Results: At the variance of task-irrelevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.482$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.899$, p>.05) and group ($F_{1,16}=1.039$, p>.05). At the variance of task-relevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.382$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.754$, p>.05) and group ($F_{1,16}=1.106$, p>.05). Conclusion: The results of this study showed that the 8 weeks training through the core training equipment for the elderly showed a significant decrease in the $Vcm_{TIR}$ and $Vcm_{TR}$. This result indicates that the core strength training affects the trunk stiffness control strategy to maintain balance in the standing position by minimizing total variability of individual segment CMs.

• Journal of architectural history
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• v.28 no.3
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• pp.29-44
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• 2019

A major performance stage carpenter, Jang Insang led performance stages from the 1719 Sukjong Royal Banquet and was confirmed by historical records to be the first craftsman. Lee Wandeuk led the Hwaseong Fortress performance stages of the Jeongjo period and Gichuk Jinchan performance stages of the Sunjo period. The carpenter techniques he used during the Jeongjo period were succeeded to the Sunjo period. Ahn Sungil was the head craftsman who led the performance stages of Jagyeongjeon Jinjak, Muja Jinjak, and Gichuk Jinchan of the Sujo period, under which the foundation for court palace performances was laid. The progression of major carpenters includes Jang Insang of the Sukjong period, Jeon Yoochu of the Yeongjo period, Ahn Sugil of the Sunjo period, Yoon Seoksin of the Heonjong period, Kim Yoonsik of the Gojong period, Lee Jongyoon, Kim Soongil, Seo Sangmook, and Han Sujoon. In addition, the Major Repair of Injeongjeon Hall (1857) of the Cheoljong period was the most important palace construction project for transferring the carpenters' skills. Through this project, Ahn Sungil of the Sunjo period, Kim Myeonggap, Yoon Seoksin of the Heonjong period, Kwon Deuknyang, and Kim Sungil of the Gojong period were able to interact with each other. That is, this major repair project of Injeongjeon Hall reflected the major carpenters' best techniques through performance stage construction, showing the progression of Ahn Sungil, Yoon Seokshin, and Kim Sungil, who led the constructions of Gichuk Jinchan of the Sunjo period (1829), Mushin Jinchan of the Heonjong period (1848), and Jeonghae Jinchan of the Gojong period (1887), the most impressive performance stages of the late Joseon period. The carpenters of the court performance stages participated in important construction projects of the royal palace, reflecting the superior technical skills of the carpenters in the construction of court palace performance stages. The carpenters who played a leading role in the construction of performance stages were able to interact with one another and transfer their excellent technical skills, providing the driving force that allowed court performance stages to blossom into splendid and high-quality court stages in the late Joseon Dynasty.

• Korean Journal of Heritage: History & Science
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• v.37
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• pp.213-242
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• 2004

"China", "Guang-Xi(廣西)", "Dong-Shan(東山)", a marriage of "Yao-zu(瑤族)" divide mainly into a distinguished family form, but are by a marriage of a traditional general form (a woman getting married) and "Zhaoxu-Hun(招婿婚)", a marriage of "Liangtou-che(兩頭扯)". These two marriage format that mentioned the back is a marriage format to often appear in other Chinese minority race region while being a custom peculiar to "Yao-zu(瑤族)" marriage method. "Zhaoxu-Hun(招婿婚)" provides labor force as a workman while living with a man sinks with "son-in-law" to a woman house, and doing, and it is to carry out a lot of duty as a husband too. "A Liangtou-che(兩頭扯)" marriage is more characteristic, but lives while going around a bilateral family while man and woman each stay in an own house. There are inheritance of property rights to own family, too and obeys anger of he direction family bilateral where if lays a child even if stands up and holds a memorial service. At the same time that these marriages are performed between the same "Yao-zu(瑤族)" near a track, and solution does a distribution problem between a labor problem and the families which were unstable through a mutual marriage for the purpose a compunction "Yao-zu(瑤族)" social network construction into intimacy anger. A general idea is covered he base with in order the porcelain which is a weak race prevent that it is assimilated by external aggression because "Yo-zu(瑤族)" has always received aggression of "a Han-zu(漢族)" too historically, and to keep an ethnic pure blood.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.1
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• pp.62-73
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• 2019

Recently, copper alloy netting has been proposed as a material for aquaculture facilities that can be set in harsh offshore environments. To design a cage made of copper alloy netting, it is necessary to calculate the flow of water through the netting and force of external sources on the netting. Therefore, this study measured and analyzed the current velocity reduction after passing through the netting and the hydrodynamic forces acting on the netting using copper alloy netting with nine solidity ratios. As a result of the reduction rate of the flow velocity through the netting, the flow reduction rate was increased as the solidity ratio of netting was increased. The flow reduction rate was also increased as the attack angle on the netting was decreased. In analyzing the resistance on the netting, we also discovered that resistance was increased with increase in the flow velocity and solidity ratio. An analysis of the hydrodynamic coefficient acting on the netting is shown that the drag coefficient tends to increase as the attack angle increases. We also analyzed the hydrodynamic coefficient according to the variation of the Reynolds number. When the drag coefficients acting on the netting were analyzed with the different Reynolds numbers, the Reynolds number increased from over 0.3 m/s to a relative constant. Finally, the copper alloy nettings had a smaller velocity reduction rate when comparing the flow velocity reduction rate between copper alloy nettings and nylon nettings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.166-172
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• 2019

A case study was performed in order to develop well-designed of thin plate door impact beam. The conventional impact beam was consisted of steel-pipe welded two brackets on the both side, which causes low productivity and high cost. In order to overcome those disadvantage, it is necessary to develop a new type of door impact; thin plate impact beam. The thin plate impact beam was not needed a welding procedure, which can lead low cost and high productivity. In order to maximally resist from an external force, the cross-section design should be well designed. 6 different cross-section design were proposed based on engineer's experience. Three point bending test was simulated those 6 different impact beam and compared the reaction forces. Among them, one case was chosen and redesigned for detail design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.3
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• pp.369-380
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• 2019

When a extreme loading such as blast is applied to prestressed concrete (PSC) structures and infrastructures for an instantaneous time, serious property damages and human casualties occur. However, a existing design procedure for PSC structures such as prestressed containment vessel (PCCV) and gas storage tank do not consider a protective design for extreme internal blast scenario. Particularly, an internal blast is much more dangerous than that of external blast. Therefore, verification of the internal blast loading is required. In this paper, the internal blast resistance capacity of PSC member is evaluated by performing internal blast tests on RC and bi-directional PSC scaled down specimens. The applied internal blast loads were 22.68, 27.22, and 31.75 kg (50, 60, and 70 lbs) ANFO explosive charge at 1,000 mm standoff distance. The data acquisitions include blast pressure, deflection, strain, crack patterns, and prestressing force. The test results showed that it is possible to predict the damage area to the structure when internal blast loading occurs in PCCV structures.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8
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• pp.1186-1194
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• 2019

Objective: The influence of broiler carcass scalding conditions on chicken breast meat quality parameters was investigated. Methods: Two hundred and seventy Cobb broiler chickens from 42 to 48 days old were slaughtered according to the standard industry practice and scalded in five temperature/time combinations-$T_1$, $54^{\circ}C/210s$; $T_2$, $55^{\circ}C/180s$; $T_3$, $56^{\circ}C/150s$; $T_4$, $57^{\circ}C/120s$; $T_5$, $58^{\circ}C/90s$. Results: Scalding temperature increase resulted in higher values of external and ventral lightness and in protein functionality reduction-determined by emulsification capacity and protein denaturation-in chicken breast fillets 24 h post-mortem. Protein secondary structures had conformational changes, with a decrease of the ${\alpha}$-helix and an increase of the ${\beta}$-sheet and ${\beta}$-turn proportions, mainly in $T_1$ and $T_5$ samples, determined by Fourier-transform infrared spectroscopy in an attenuated reflectance mode analysis. The chemical composition, pH, water holding capacity and Warner-Bratzler shear force did not differ among the treatments. In the fatty acid profile, the 18:1n-9 was lower in $T_5$, which suggested that the high scalding-temperature could have caused the lipid oxidation. The values of the polyunsaturated fatty acids (PUFA), such as 22:2, 20:4n-6, and 22:6n-3, were highest in the $T_5$, thus being related to the phospholipid cellular membrane collapse in this experimental condition and subsequent release of these PUFA. Conclusion: Intermediate scalding-parameters avoided the negative changes in the chicken meat quality.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.97-104
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• 2019

The construction industry is heavily dependent on labor force as automation to building constructions is difficult due to its characteristics such on-site production, custom manufacturing production. Thus, while securing and fostering high-quality functional manpower for stable construction work are significant, the construction workforce has been persistently lacking compared to demand. Young workers are reluctant to enter the construction industry due to high labor intensity, unstable employment structure, and uncertainty for the future. The employment rate for new jobs in the construction industry is half as high as in others. Currently, the departments related to construction are organized in specialized high school to conduct training for young workers. The graduates have a low ratio of employment rate to the construction industry and functional capacities fallen short of expectations. In this study, the education and training conditions of specialized high schools were analyzed to derive problems and key improvements of the education system were drawn. As an improvement for the analysis results, it provides solutions such as giving advantages of previous education experience, expand industry-academic cooperation with businesses, and expand links with external educational institutions.