• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.22-30
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• 2000

The present article deals with comparisons of published liquid breakup models for diesel sprays to analyze the influence of breakup models on various spray parameters. The three different models tested in this study are the surface wave instability (Wave) model, the Taylor analogy breakup (TAB) model, and the drop drag model(DDM). The numerical results using these models are compared with several experimental data to assess the prediction capabilities of breakup models. Additional task in this study is to investigate effects of the breakup time constant in the Wave model on the spray parameters because the spray behavior is sensitive to the breakup time constant. It is seen that there is uncertainly about the breakup time constant indicating that the suitable acceptance of the constant is important, and the TAB model generally shows significant under-prediction of Sauter Mean Diameter(SMD). In addition, it may be indicated that differences between the DDM and Wave model are not significant, showing that the DDM may be suitable for air-assisted atomization rather than pressure atomization.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.176-176
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• 2010

OLED(Organic Light Emitting Device)는 LCD(Liquid Crystal Display)의 뒤를 잇는 차세대 디스플레이의 선두주자로서 자체발광형이기 때문에 백라이트 등의 보조광원이 불필요하며, 구동전압이 낮고 넓은 시야각과 빠른 응답속도 등의 특징을 가지고 있다. 또한 플렉서블 기판을 사용할 수 있어 차세대 디스플레이인 플렉서블 디스플레이에 적합하다. 플렉서블한 디스플레이를 만들기 위해서 플라스틱 기판에 OLED 물질을 사용하여 기존에 무겁고, 깨지기 쉬우며, 변형이 불가능한 유리로 만든 소자 보다 더 가볍고 깨지지 않고 변형이 가능한 플렉서블 디스플레이를 제작 할 수 있다. 그러나 플라스틱 기판은 매우 큰 투습율을 가지고 있어 OLED소자에 적용시키면 공기 중의 수분이나 산소와 접촉이 많아져 쉽게 산화되어 소자의 효율 및 수명이 짧아진다. 또한 OLED에 사용되는 유기물도 산소나 수분에 의해 특성이 급격히 저하되기 때문에 산소 및 수분의 차단은 필수적이다. 이러한 단점을 최소화하기 위해서 PECVD(Plasma Enhanced Chemical Vapor Deposition)로 만든 SiON(Silicon Oxynitride), $SiO_2$(Sillicon dioxide), $Si_3N_4$(Sillicon nitride) 박막을 차단막(Passivation layer)으로 사용하였다. PECVD(Plasma Enhanced Chemical Vapor Deposition)로 만든 SiON(Silicon Oxynitride), $SiO_2$(Sillicon dioxide), $Si_3N_4$(Sillicon nitride) 각각의 박막의 Crack의 특성을 85%-$85^{\circ}C$조건에서 24hr 측정하였다.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.163-167
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• 1993

We developed a ventricular assist device(VAD) to be used as a bridge to heart transplantation or a circulatory assist device for patients with end-stage heart disease or poor myocardial function after cardiac surgery. It is a pneumatic and diaphragm-type VAD and its stroke volume is 90 cc. The upper housing and diaphragm is made of a segmented polyurethane and the lower back plate is made of a polycarbonate. Two Carbomedics$^R$ mechanical valves are used as inlet and outlet valves. It was tested in vitro and the cardiac output of the VAD was 7 L/min at a heart rate of 70 bpm. The line pressure from a pressure transducer inserted in the pneumatic line was recorded and compared with the ideal pressure tracing.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.519-528
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• 2019

Current brake system changes the kinetic energy into heat energy by friction-type of brake that the braking action is diverging into the air. The system has a device called a retarder that generates braking force. High-tech research on the high-speed response characteristics of retarders utilizing part of the braking energy of the retarder to save electrical energy consumption is already underway in advanced countries. In this paper, we propose DC-DC converter which converts 3-phase voltage generated from retarder to 24V DC voltage for battery charging and verify its validity through experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.51-58
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• 2022

This paper proposes new measures to aid the uses of pubic transport buses by visually impaired people. Many visually impaired people have difficulty using public buses, but current guidance systems and braille blocks are not useful enough, according to a national survey(2017). In this paper, we develop a system with three functions that help to increase the bus accessibility and mobility of visually impaired people: (1)bus reservation using smart phone applications, (2)arrival notification, and (3)wireless bus stop button using Beacon. Experiments have confirmed that our system supports bus reservation, boarding and getting off the bus efficiently.

• Journal of Animal Science and Technology
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• v.44 no.4
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• pp.475-482
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• 2002

The experiment was conducted to evaluate a ventilation system, which was devised to encourage farmers to use the enclosed poultry housing system. The study was observed in the National Livestock Research Institute from May 9 to May 30 in 2002. The main results of the experiment are as follows: 1. Although the outside temperature of the enclosed poultry house was 9.6 ${\sim}$ 21.2$^{\circ}C$ with 11.6$^{\circ}C$ variation, the house with an excellent heat insulation was maintained at 32${\sim}$33$^{\circ}C$ in a variation of 2$^{\circ}C$ which is within the range of the optimal temperature for broiler, being aided with two small electric heaters. 2. The average of air flow rates of the upper, middle and low parts of the room in the broiler house were detected at 0.57, 0.22 and 0.04 m/sec, respectively. The air flow in the whole room was distibuted uniformly by a perforated duct. In conclusion, heat and humidity could be controlled without any problem in this enclosed housing system. Especially, air flow in all parts of the room was detected in uniform rates, resulting in the better ventilation performance with air inhalation through the duct and air exhaust through the side walls of the house.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.197-206
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• 2023

Recently, the international community, including the International Maritime Organization (IMO), has strengthened regulations on air pollution emissions of ships, and eco-friendly ships are actively being developed to reduce exhaust gas emissions. Among them, rotor sail (RS), a wind-assisted ship propulsion system, is attracting attention again. RS is a cylindrical device installed on the ship deck, that generates hydrodynamic lift using a magnus effect. This is a next generation eco-friendly auxiliary propulsion technology, and Enercon company, which developed RS-applied ships, announced that fuel savings of more than 30% are possible. In this study, optimal installation conditions such as RS spacing and arrangement type were selected when multiple RSs were installed on ships. AR=5.1, SR=1.0, and D_e/D was fixed at 2.0 according to the RS arrangement, and the wind direction was considered only for the unidirectional +y-axis. Regarding arrangement conditions, five conditions were set at 3D intervals in the +x-axis direction from 3D to 15D and five conditions in the +y-axis direction from 5D to 25D. C_L, C_D and aerodynamic efficiency (C_L/C_D) were compared according to the square(□) and diamond(◇) shape arrangements. Consequently, the effect of RS on the longitudinal distance was not significantly different. However, in the case of RS flow characteristics according to the transverse distance, the interaction effect of RS was the greatest when the two RSs almost matched the wind direction. In the case of the RS flow characteristics according to the arrangement, notably, when the wind blew in the forward (0°) direction, the diamond (◇) arrangement was least affected by the backward flow between RSs.

• Applied Biological Chemistry
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• v.36 no.4
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• pp.271-276
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• 1993

This study was carried out to prepare anchovy based powder for instant soup packed in tea bag which can be used handily as a extractives, and to determine the taste compounds of extractives of anchovy based powder for instant soup. The anchovy based powder for instant soup was made by adding of 72% in the redried anchovy, 14% in the sea tangle, 7% in the mushroom and 7% in the katsuobushi to the total mixtures. And the anchovy based powder for instant soup was packed in tea bag. The desirable extraction time are 5 min in package in tea bag with air permeability $100\;m^3/m^2/min$ and over 20 min in package in tea bag with air permeability $65\;m^3/m^2/min$, respectively. Judging from the result of extraction rate of total nitrogen, color and sensory evaluation in extractives of anchovy based powder for instant soup extracted by optimal extraction time, the quality in extractives of instant soup packed in tea bag with air permeability $100\;m^3/m^2/min$ was superior to those of instant soup unpacked in tea bag and of instant soup packed in tea bag of air permeability $65\;m^3/m^2/min$. The principal taste compounds of extractives of anchovy based powder for instant soup packed in tea bag with air permeability $100\;m^3/m^2/min$ were IMP (9.26 mg/100ml in 5% solution) and free amino acids (24.30 mg/100 ml in 5% solution) such as histidine, proline, lysine and taurine. Total creatinine, betaine and TMAO were seemed to act an auxiliary role in taste of extracives of anchovy based powder for instant soup packed in tea bag with air permeability $100\;m^3/m^2/min$.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.27-39
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• 2009

The main objective of this study is to investigate the characteristics of combustion by analyzing fuel gases from a combustion equipment with various combustion conditions for refuse-derived fuels (RDFs). CO gas is a parameter for indicating of incomplete combustion during a combustion process. The lowest CO gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. $CO_2$ gas is a final product after complete combustions. The highest amount of $CO_2$ gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. The highest level of $SO_2$ gas was produced in S.1 sample containing the highest sulfur. The highest level of NOx gas was produced in S.1 sample with the highest nitrogen content and air-fuel condition of m=2 under temperature of $800^{\circ}C$. HCl gas that is generated by reacting with metals catalyst through oxygen catalyst reaction during combustion process is a precursor of dioxin formation. The higher level of HCl gas was produced in the sample with higher chlorine content. The lowest level of HCl gas was produced when the experiment conditions were air-fuel condition of m=2 and $800^{\circ}C$. The lowest level of $NH_3$ gas was generated when the experiment condition was m=2 under air-fuel condition and after 3 minutes. Air-fuel condition is more important to create $NH_3$ gas than operating temperatures. Higher level of $H_2S$ gas was generated in S.1 sample with the higher sulfur content and was created in RDFs that contain higher mixture ratios of sewage sludge and food wastes. A result of combustion, gases and gases levels from the combustion of S.1 and S.2 were very similar to the combustion of a stone coal. As results of this research, when evaluating the feasibility of the RDFs, the RDFs could be used as auxiliary and main fuels.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.975-991
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• 1997

Background : Many patients with isoniazid and rifampin-resistant pulmonary tuberculosis have organisms that are also resistant to other first-line drugs. Despite of aggressive retreatment chemotherapy, the results are often unsuccessful, with a failure rate approaching 40%. Recently, there has been a revival of resectional surgery for the treatment of multidrug-resistant pulmonary tuberculosis. Methods : A retrospective analyses of the case records and radiographic findings were done. Between January 1991 and December 1995, 14 human immunodeficiency virus (HIV)-seronegative patients with multidrug-resistant pulmonary tuberculosis were selected for resection to supplement chemotherapy. All patients had organisms resistant to many of the first-line drugs, including both isoniazid and rifampin. Results : Despite of aggressive therapy for median duration of 9.5 months, 12 of the 14 patients (86%) were still sputum smear and/or culture positive at the time of surgery. The disease was generally extensive. Although main lesions of the disease including thick-walled cavities were localized in one lung, lesser amounts of contralateral disease were demonstrated in 10 of 14 (71%). Types of surgery performed were pneumonectomy including extrapleural pneumonectomy in six patients, lobectomy or lobectomy plus in six patients, and segmentectomy in two patients. The resected lung appeared to have poor function ; preoperative perfusion lung scan showed only 4.8% of the total perfusion to the resected portion of the lung. There were no operative deaths. Two patients had major postoperative complications including empyema with bronchopleural fistula and prolonged air leak, respectively. Of the 14 patients, 13 (93%) remained sputum-culture-negative for M. tuberculosis for a median duration of 23 months and one remained continuously sputum smear and culture positive for M. tuberculosis. Conclusion : On the basis of comparison with historical controls, adjunctive resectional surgery appears to play a significant beneficial role in the management of patients with multidrug-resistant pulmonary tuberculosis if the disease is localized and there are adequate reserve in pulmonary function.