• 한국연소학회:학술대회논문집
• /
• 1999.10a
• /
• pp.111-115
• /
• 1999

In order to enhance the burner performance of household gas fired absorption chiller/heaters, the operating condition(excess air $\approx$ 10%) of the burner currently being used was required to be optimized. In this regard, we examined where the $CO_{\min}$. emission limit was located between blow off and yellow tip limit and how much amount of excess air was exhausted by means of observing blow off and yellow tip limit. It was found that the $CO_{\min}$ limit(excess air ${\approx}$ 4%) was determined near the yellow tip limit. The effect of exhaust pressure on the $CO_{\min}$. limit was that, if exhaust pressure was higher than that in steady condition, higher air blower fan rpm is demanded to maintain the $CO_{\min}$ limit. Therefore, it was necessary to optimize the operating condition of burner in terms of a thermal efficiency and safety.

• International Journal of Internet, Broadcasting and Communication
• /
• v.12 no.2
• /
• pp.30-36
• /
• 2020

We demonstrated a successful fabrication of 4" Gallium Nitride (GaN)/Diamond High Electron Mobility Transistors (HEMTs) incorporated with Inner Slot Via Hole process. We made in manufacturing technology of 4" GaN/Diamond HEMT wafers in a compound semiconductor foundry since reported [1]. Wafer thickness uniformity and wafer flatness of starting GaN/Diamond wafers have improved greatly, which contributed to improved processing yield. By optimizing Laser drilling techniques, we successfully demonstrated a through-substrate-via process, which is last hurdle in GaN/Diamond manufacturing technology. To fully exploit Diamond's superior thermal property for GaN HEMT devices, we include Aluminum Nitride (AlN) barrier in epitaxial layer structure, in addition to conventional Aluminum Gallium Nitride (AlGaN) barrier layer. The current collapse revealed very stable up to Vds = 90 V. The trapping behaviors were measured Emission Microscope (EMMI). The traps are located in interface between Silicon Nitride (SiN) passivation layer and GaN cap layer.

• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.173-174
• /
• 1996

We have mapped $17 deg^2$ region toward Galactic anticenter in $^{12}CO$ J = 1 - 0 using the 3 mm SIS receiver on the 14 m telescope at Taeduk Radio Astronomy Observatory (TRAO). The region mapped in this paper is the first target of the Galactic AntiCenter CO Survey Project (GACCOS) and was selected comparing with IRAS Sky Survey Atlas (ISSA) images at 100${\mu}m$. Molecular emission of the target area is found to be very extended and is well matching with the FIR emission boundary. There are several pieces of clouds, and as some of spectra show several peaks, there seem to be several clouds overlapped in some directions. The Velocity of Local Standard of Rest ($V_{LSR}$) of the CO emission of the mapped region ranges from -20 to +10 km/s. It is also found that the two cloudlets located around I = $180^{\circ}$ have $V_{LSR}$ = -20 km/s, which is very abnormal. The peak antenna temperature of 13 K arises near the H II Region S241.

• Journal of The Korean Society of Inherited Metabolic disease
• /
• v.16 no.1
• /
• pp.42-46
• /
• 2016

Isovaleric acidemia is autosomal-recessively inherited and an inborn error of metabolism caused by abnormal leucine metabolism due to the genetic defect of IVD (Isovaleryl-CoA dehydrogenase). IVD corresponds to mitochondrial matrix enzyme that acts on converting isovaleryl-CoA into 3-methylcrotonyl-CoA in the leucine catabolism. The IVD gene is located at Chromosome 15q14-q15, particularly between base pair 40,405,485 and base pair 40,435,948. It consists of 12 exons and has been reported to cause over 50 diseases so far. We conducted IVD gene test on the patient with acute isovaleric acidemia and confirmed a new type of mutation for the first time. As a result of analyzing the IVD gene sequence, we found out that c.129T>G(p.Asn43Lys) and c.1033A>G(p.Asn345Asp) mutations exist as heterozygosity at Exon 1 and Exon 10 respectively, novel mutation.

• Journal of the Korean Society of Combustion
• /
• v.20 no.4
• /
• pp.19-25
• /
• 2015

An experimental study was conducted to find the effect of a pilot flame on the flammability of inert-gas-diluted methane and propane. The diffusion pilot flame was formed with propane at the innermost nozzle of a concentric triple co-flow burner. The main diffusion flame was formed with nitrogen-diluted methane or propane at the outermost nozzle of the burner. An air flow was located in-between. The results showed that the existence of the pilot flame helped stabilizing the main flame even at the flammability limit concentration of nitrogen-diluted fuel. The co-flow burner generated re-circulation zones and local variation of equivalence ratio depending on the flow rates of the reactants, which are known to help flame stabilization. Hot-wire experiments confirmed that both heating of the reactants and supplying of active chemical species by the pilot flame contributed to stabilization of the main flame. The results of this study would suggest a design concept for an efficient SVRU system that minimizes the emission of unburned hydrocarbon fuel from ship fuel tanks.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.829-834
• /
• 2009

Alluvial soil is one of the most difficult grounds for tunneling works due to the insufficient ground strength and excessive ground water inflow. Dduk island in Seoul has a wide alluvium developed by two rivers, Han and Jung-Ryang. Subway tunnel of $\bigcirc\bigcirc$ line planed across Dduk island has highly poor ground conditions due to small cover and deeply developed alluvium. Moreover, much part of this tunnel is located parallel to the bridge foundations of another railway with a small horizontal distance. Original design was done in 2002 and construction has been in progress. During the construction, tunnel design has been partly changed and adjusted for the complex ground condition and the demand from related organizations. This paper intend to introduce the urban tunnel design and construction in alluvial soils. This line could be divided three sections(A, B, C) according to ground and adjacent conditions. Section A is featured by mixed tunnel faces consisted with alluvial soils and weathered or weak rocks. The feature of section B is that tunnel underpasses near the bridge foundations of another subway. Lastly, section C with a very short length is the most difficult construction conditions due to the small cover, poor ground, obstacles on and underneath ground surface.

• Korea Journal of Hospital Management
• /
• v.25 no.1
• /
• pp.58-72
• /
• 2020

Purposes: This study aims to investigate the determinants of change-oriented organizational citizenship behavior(CO-OCB) of hospital employees and test the mediating effect of the job satisfaction and organizational commitment on the CO-OCB. Methods: Data were collected from the self-administered questionnaire survey for hospital employees of ten hospitals located in five regions, including Seoul. Out of 1,100 questionnaires which were distributed through the administrative routes, a total of 617 copies were returned(response rate 56.1%) and analyzed by frequency analysis, t-tests, correlation analysis, multiple regression, and path analysis using SPSS 21.0 and AMOS 21.0. Findings: The study results revealed that the explanatory power(56.4%) of the model was most significantly increased by the variables of psychological attributes(R²-change 33,5%). Also, the variables of self-efficacy, followed by hope, the organizational climate for innovation, the psychological safety climate, team-member exchange, and leader-member exchange were found to have positive total effects on CO-OCB, through the mediating variables of job satisfaction and organizational commitment. Practical Implications: The study results imply that, in order to improve the CO-OCB of hospital employees, the administrators have to take the integrated approach considering the various domains of factors including the psychological attributes, job characteristics, interpersonal relations, and organizational climate simultaneously.

• Journal of the Korean Ceramic Society
• /
• v.47 no.5
• /
• pp.357-364
• /
• 2010

This study was performed to get basic information about properties of high blaine slag cement(HSC) to use shotcrete(or sprayed concrete and mortar). Particle size distribution, setting time and compressive strength test, analysis like as SEM, DSC thermal analysis, XRD was carried out to investigate principle properties of HSC. Setting time of HSC was delayed slightly, but influence of accelerators was more bigger than ordinary portland cement(OPC). Compressive strength of HSC at 28 days was more higher than OPC regardless of using accelerators. Results of analysis showed early period hydration products of HSC is more small and located widely, because of the interface of between cement particle and water is increased as specific surface of cement increase. From the SEM observation and analysis of DSC and XRD results, aluminates accelerators bring on some hydration products like as calcium aluminium hydrates, alkali free accelerators increases ettringite and monosulfates. Aluminates accelerators has a advantage of setting time and early strength, alkali free accelerators increases strength after 7 days.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2015.09a
• /
• pp.74-78
• /
• 2015

When floating platform or drilling unit is located at operating station during its design life, it has to have the sufficient stability considering external environment. To evaluate whether offshore structure is complied with the required design criteria for intact stability, the factors which decrease the righting moment have to be considered. Wind heeling moment is one of main factors because the direction is opposite to the righting moment. According to 2009 MODU CODE (Code for the construction and equipment of Mobile Offshore Drilling Units, 2009), wind heeling moment derived from wind tunnel test on scale model of offshore structure enables to apply as alternative given formula and method in 2009 MODU CODE. However, there is no the specific method for applying data derived from wind tunnel test. Based on the following reasons, this paper presents that the calculation method of wind heeling moment utilizing non-dimensional coefficient relative to wind loads (wind forces and moments) and the comparison with each method applying an example.

• The Korean Journal of Food And Nutrition
• /
• v.34 no.1
• /
• pp.132-136
• /
• 2021

The purpose of this study is to measure the levels of eluted and dissolved CO2, and CO, volatile organic substances and radiation composition of Cheongsong mineral water which were collected from November 2019 to July 2020 during the autumn, spring, and summer seasons at collection points located in the upper, middle and lower spring waters. Data of the upper, middle and lower spring waters include the following: the amount of eluted water (average value±standard deviation, mL/min) was 30.07±0.52, 15.03±0.16, 23.73±0.42, and the amount of CO2 gas was 1,000 ppm or more. In addition, there was no detection of CO or total volatile organic substances (TVOC) and the radiation dose was 0.08 to 0.13. μSv/h. A blank test value of 0.08 to 0.10 μSv/h, when compared with the median value, showed a high value of 0.02 μSv/h, and the uranium test results provided by the Cheongsong-gun Office were 0.0118 mg/L (date 2019.06.18) and 0.0091 mg/L (date 2020.06.04.) respectively, which was less than the permission limit of 0.03 mg/L. However, it is believed that further research using more precise devices is needed in order to guarantee the safety and health of the water.