• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.65-68
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• 2018

The anatomical study of the olfactory organ in Liobagrus somjinensis, being related to the habitat environment and ecological habit, was carried out using a stereomicroscopy and digital camera. The paired olfactory organs are situated at the dorsal part of the snout, and consisted of two opening (anterior and posterior nostrils) and the olfactory chamber. The tubular anterior nostril is located between the tip of upper lip and the nasal barbel. The posterior nostril flat to the surface is adjacent entirely to the basement of the nasal barbel. The olfactory chamber has a rosette structure with 22~24 lamellae of linguiform, arranged transversely and radially from the medium raphe. These results may prove that L. somjinensis is dependent on olfaction, related to the hiding, the feeding and the nocturnal lifestyle in rapids.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.2
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• pp.93-102
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• 2016

An experimental study has been conducted to verify the startup characteristic of a Center Body Diffuser (CBD) for simulating a low pressure environment when at high altitudes. Vacuum chamber pressure and startup characteristics of the CBD were investigated according to various geometries of the center body structure by a cold gas flow test. The test results show that the startup pressure is lowest when the center body contraction angle is approximately $15^{\circ}$. The startup characteristic of the CBDs significantly improves when the diffuser inlet length ($L_d/D_d$) is decreasing and the divergence length ($L_s$) is increasing. Additionally, it is possible to simulate various high altitude, low pressure conditions for various rocket engines that have different nozzle expansion ratios by adjusting the center body's position inside the diffuser.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.351-358
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• 2006

The capability of high pressure injection with small fuel quantify at all engine operating conditions is one of the main feature in common rail fuel injection system, which is used in small and light-duty Diesel engine. The key parameter for the better atomized fuel sprays and multiple injections of this common rail fuel injection control, that can be freely selected irrespective of the engine speed and load is the mechanism controlling the needle energizing and movement in high pressure Diesel injector. In the electro-hydraulic injector, the injection nozzle is being opened and closed by movement of the injector's needle which is balanced by pressure between the nozzle seat and the needle control chamber. This study describes the macroscopic spray structure characteristics of the common rail Diesel injectors with different electric driving method i.e. the solenoid-driven and piezo-driven type. The macroscopic spray characteristics such as spray tip speed. spray tip penetration and spray cone angle were investigated by the high speed spray, which is measured by the back diffusion light illumination method with optical system for the high speed temporal photography in a constant volume chamber pressurized by nitrogen gas. As the results, the prototype piezo-driven injector system was designed and fabricated for the first time in domestic case and the effect of injector's needle response driven by different drive type was compared between the solenoid and piezo-driven injector It was found therefore. that the piezo-driven injector showed faster needle response and had better needle control capability by altering the electric input value than the solenoid-driven injector.

• Transactions on Electrical and Electronic Materials
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• v.11 no.2
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• pp.73-76
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• 2010

The copper indium disulfide ($CuInS_2$) thin film was manufactured using sputtering and thermal evaporation methods, and the annealing with sulfurization process was used in the vacuum chamber to the substrate temperature on the glass substrate, the annealing temperature and the composition ratio, and the characteristics thereof were investigated. The $CuInS_2$ thin film was manufactured by the sulfurization of a soda lime glass (SLG) Cu/In/S stacked [1] elemental layer deposited on a glass substrate by vacuum chamber annealing [2] with sulfurization for various times at a temperature of substrate temperature of $200^{\circ}C$. The structure and electrical properties of the film was measured in order to determine the optimum conditions for the growth of $CuInS_2$ ternary compound semiconductor $CuInS_2$ thin films with a non-stoichiometric composition. The physical properties of the thin film were investigated under various fabrication conditions [3,4], including the substrate temperature, annealing temperature and annealing time by X-ray diffraction (XRD), field Emission scanning electron microscope (FE-SEM), and Hall measurement systems. [5] The sputtering rate depending upon the DC/RF power was controlled so that the composition ratio of Cu versus In might be around 1:1, and the substrate temperature affecting the quality of the film was varied in the range of room temperature (RT) to $300^{\circ}C$ at intervals of $100^{\circ}C$, and the annealing temperature of the thin film was varied RT to $550^{\circ}C$ in intervals of $100^{\circ}C$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.4
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• pp.397-405
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• 2004

In this paper, performance analysis of mobile phone with internal antenna for PCS band was carried out. The radiation patterns for antenna and mobile phone with internal antenna were simulated by using 3D simulation program, HFSS and SEMCAD. Radiation pattern variation was observed according to installation of LED circuit and ground pattern and by using simulation radiation pattern was improved. And radiation patterns of mobile phones with internal and external antennas were measured by using for field measurement system and chamber. Measured radiation pattern for mobile phone with internal antenna shows good agreement with simulation result. And the radio sensitivities of mobile phones with internal and external antennas were measured by using Agilent E5515C and chamber and compared. The measured radio sensitivity of mobile phone with internal antenna shows proper performances comparable to other model with external antenna. Measured result shows that the difference on averaged co-polar radio sensitivity is 0.12 ㏈.

• Journal of the Korean GEO-environmental Society
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• v.18 no.11
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• pp.35-40
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• 2017

The rearside of concrete lining of tunnels constructed in cold region might experience on freezing due to the low temperature. This causes damage of concrete lining resulting in adverse affect on the durability as well as integrity of tunnel structure by causing damage to the concrete lining. In order to prevent the rearside of tunnel lining from freeing, the temperature change inside the concrete lining was measured by attaching a heating element to the tunnel lining surface and generating heat for a certain period of time. A special freezing chamber was developed to conduct the experiments considering in-situ environment. The carbone nanotube (CNT) was used as a heating element in this study. The temperature distribution of the concrete lining was measured by applying the heat to the heating element. The effect of the outside temperature and heating duration were analyzed.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.102-107
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• 2011

In this paper, a microfluidic array biochip for simultaneously detecting multiple antigen-antibody bindings was designed and implemented. The biochip has the single channel in which microreaction chambers are serially connected, and the antibody-coated microbeads are packed in each microreaction chamber. In addition, the weir structure was fabricated in the microchannel using the gray-scale photolithography in order to trap the microbeads in the microreaction chamber. Three kinds of antibodies were chosen, and the antibodies were immobilized onto the microbeads by the streptavidin-biotin conjugation. In the experiment, as the fluorescence-labeled antigens were injected into the microchannel, the antigen-antibody bindings were completed in 10 minutes. When the solution with multiple antigens was injected into the microchannel, it was observed that the fluorescence intensity increased in only the corresponding microreaction chambers with few non-specific binding. The microfluidic array biochip implemented in this study provides, even with the consumption of tiny amount of sample and fast reaction time to simultaneously detect multiple immunoreactions.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.477-483
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• 2020

The rehabilitation methods used in existing concrete box structures rely on the method of attaching the repair material to the section of the structure with a spray equipment. In the case of ceiling or wall parts, the adhesion force to the repair material may be reduced by the gravity and dead load after construction. In subway structures, vibration causes a problem that reduces the initial adhesion. Supplementary measures are needed as the quality of repair varies depending on the worker's proficiency and construction environment. In this study, mechanical pressurization equipment was developed that can apply a certain pressure after construction of a repairwork to solve problems such as reduction of adhesion of repair materials by gravity and variation of repair quality by labor work. To find out the effect of the pressurized equipment, a chamber similar to the field conditions was constructed to measure the attachment strength different from the pressurized condition, the section, and the environmental conditions. The pressurization differed from the other parts, but the adhesion strength of up to 70% was increased.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1485-1490
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• 2014

$SF_6$ gas has been used for power transformers or gas insulated switchgears, because it has the superior insulation property and the stable structure chemically. It has been, however, one of global warming gases and required to reduce the its amount. Some papers have reported that its amount could be reduced by mixing with other gases, such as $N_2$, $CF_4$, $CO_2$ and $C_4F_8$ and their mixture gases would cause the synergy effect. In this paper, we investigated the characteristics of DC plasmas on $SF_6$ mixture gases with $N_2$ at atmospheric pressure. $N_2$ gas is one of cheap gases and has been reported to show the synergy effect with mixing $SF_6$ gas, even though $N_2$ plasmas have electron-positive characteristics. 38 kinds of $SF_6/N_2$ plasma particles, which consisted of an electron, two positive ions, five negative ions, 30 excitation and vibration particles, were considered in a one dimensional fluid simulation model with capacitively coupled plasma chamber. The results showed that the joule heating of $SF_6/N_2$ plasmas was mainly caused by positive ions, on the other hand electrons acted on holding the $SF_6/N_2$ plasmas stably. The joule heating was strongly generated near the electrodes, which caused the increase of neutral gas temperature within the chamber. The more $N_2$ mixed-ratio increased, the less joule heating was. And the power consumptions by electron and positive ions increased with the increase of $N_2$ mixed-ratio.

• Journal of Ocean Engineering and Technology
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• v.30 no.4
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• pp.277-286
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• 2016

The first part of this study found the tendencies of the mechanical properties of two arctic structural steels (EH32 and FH32). In the second part, the crashworthiness of stiffened panels scaled down from the side frame structure of a Korean research icebreaker was determined. A procedure for designing the shapes and sizes of the stiffened panels, mass and shape of a drop striker, and a large temperature chamber, and then manufacturing these, is introduced in detail. From impact bending tests for the stiffened panels, the residual permanent deformations and deformation histories over time were captured using manual measurement and video image analyses. Numerical simulations of the impact bending tests were carried out for three different finite element models, which were mainly composed of shell elements, solid elements, and solid elements, with welding beads. It was proven from a comparison of the test results and numerical simulation results that the solid element model with the welding bead consideration approached the test results in terms of the residual deformations as long as the strain rate effect was taken into account.