• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.254-256
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• 1999

• Journal of the Korean Society of Combustion
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• v.17 no.4
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• pp.11-20
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• 2012

The Blow-off characteristics of LPG/air lean pre-mixed flames were experimentally investigated using a double and a multiple concentric coflow burners. Experiments were conducted to understand the effects of recirculation motion, thermal interaction between flames, and stratified flame configuration. Here, the stratified premixed flame is a "new concept" of a flame that sequentially contains fuel rich, stoichiometric, and fuel lean reaction zones in a flame. The blow-off from a lean premixed flame was significantly suppressed with recirculation motion. The recirculation motion by itself, however, was not sufficient to prevent the blow-off when the equivalence ratio became low. The existence of a inner premixed flame could also help to prevent the blow-off of lean premixed flame; however, the blow-off suppression effect was rather diminished by weakened recirculation motion with the presence of inner flame. The inner flame could be separated from an outer flame on a multiple concentric coflow burner, causing recirculation motion as well as thermal interaction between flames to become effective; therefore, the blow-off was further suppressed. The lean premixed flame could be stabilized with a fuel rich premixed flames that was produced with the supply of fuel through an inner nozzle. The penetration of lean premixed gas from outside into the fuel stream produced a lifted rich premixed flame. Chemiluminescence images of OH, CH, and $C_2$ radicals confirmed the structure of a stratified premixed flame. The stable premixed flames could be obtained at the very fuel lean condition by applying the stratified premixed flame concept.

• Design & Manufacturing
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• v.17 no.3
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• pp.1-7
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• 2023

Blow molding is a manufacturing process in which thermoplastic preforms are preheated and then pneumatically expanded within a mold to produce hollow products of various shapes. The two-step process, a type of blow molding method, requires the output of multiple infrared lamps to be adjusted individually, so the process of finding initial conditions hinders productivity. In this study, digital twin technology was applied to solve this problem. A blow molding simulation technique was established and simulation-based metadata was generated. A response surface ROM (Reduced Order Model) was built using the generated metadata. Then, a dynamic ROM was constructed using the results of 3D heat transfer analysis. Through this, users can quickly check the product wall thickness uniformity according to changes in the control value of the heating lamp for products of various shapes, and at the same time, check the temperature distribution of the preform in real time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.459-462
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• 2017

This paper, A large hair dryer was developed to shorten the drying time of the user's hair. The mechanism that determines the strength and stability of large hair dryer products is 'motor'. In a typical hair dryer to determine the wind speed using a 5V or 12V DC motor, Outer air vents are also great ways to use a long time, power consumption by a single blow. But, In the case of large hair dryers using multiple blows, the aim is to reduce the power consumption by increasing the intensity of the wind speed in a short time. Looking at the simulation results of a typical hair dryer, It was found that women spent an average of 20 minutes and that large hair dryers took an average of 5 minutes. This paper, In order to shorten the average drying time, it is necessary to determine the efficiency of the motor, the blow position of the outer frame, and the power consumption and studied for product development. As a result of the research and simulation, the power consumption is 0.8 times, the wind speed is 1.5 times, and the drying time is about 5 minutes. Therefore, it was found that the large hair dryer developed in this study can maximize the user 's average drying time and the efficiency of the motor.

• Journal of Welding and Joining
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• v.11 no.1
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• pp.42-51
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• 1993

In this study, investigations were conducted in calculating parameters of elastic-plastic fracture mechanics using single specimen. The validity of these testing methods was judged by the confirmation of multiple specimen method of stop block test. The results were as follows: In order to measure a fracture toughness using the instrumented impact test, two general requirement must be considered; One, setting up proper impact velocity considered the effect of loading and the other, the necessity of low blow test for obtaining true energy by the compliance correction. It was possible to detect a crack initiation point by calculating the compliance changing rate from a load-defection curve. Criterion of a stable crack growth, $T_{mat}$ could be estimated by using key-curve method for a base metal. and combining Kaiser's rebound compliance with Paris-Hutchison's $T_{appl}$ equation for the brittled zone of welding heat affected.at affected.d.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.5
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• pp.23-31
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• 2001

A very compact narrowband high-temperature superconducting microstrip filter using multiple coupled line resonators is designed and fabricated to effectively use the limited space of the wafer. The fabricated 12 pole filter has a center frequency of 1.79 GHz and a 3dB bandwidth of 7.63 MHz(0.43% fractional bandwidth). The filter also shows sharp skirt characteristics of 71 dB/MHz and 41dB/MHz blow and above the passband, respectively, and has an insertion loss of less than 0.5dB and a return loss of more than 15dB in the passband.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.1
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• pp.30-38
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• 2009

The objective of this study was to evaluate the effects of occupational exposure to styrene on the components of metabolic syndrome. We surveyed 263 employees, among whom 117workers we ere chronically exposed to styrene in glass-reinforced plastic boat manufacturing factories and 146 controls had never been occupationally exposed to styrene as will as hazardous chemicals. The general and job characteristics such as age, smoking and drinking habit, working hours and duration were not significant different except sleeping hours(p<0.05). Among the components of metabolic syndrome, the systolic blood pressure, total cholesterol, HDL-cholesterol and fasting glucose were significantly higher in exposed workers. On multiple logistic regression analysis for the components of metabolic syndrome, waist circumference was insulin (OR=1.129), blood pressure was MA(OR=14.724), fasting glucose(OR=1.191) and metabolic syndrome(OR=1.110) were significantly associated with insulin. The mean concentration of airborne styrene was $ 38.1{\pm}40.1$ ppm, blood concentrations of glucose and insulin and levels of HOMA-IR in over 50 ppm exposed group were higher than in blow 50 ppm exposed group. These results suggested that the exposure of styrene affects blood pressure, fasting glucose and insulin levels and that dysfunction and/or declination in glucose and insulin metabolism might induced ultimately insulin resistance and metabolic syndrome.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.485-493
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• 2004

The system performance of 2-Dimensional wavelength hopping/time spreading optical CDMA systems is found to be limited by the occurrence of the beat noise between the components of the signal and the multiple user interference. This paper shows that the performance is analyzed under the beat noise and no beat noise to blow impact of the beat noise. To overcome this problem, the OHL(Optical Hard-Limiter) is used in the receiver. The performance is calculated for a optical CDMA system employing asymmetric and symmetric prime-hop 2-Dimensional codes, respectively The analysis results show that the performance improved 3.5 times of simultaneous users of before and after inserting OHL in the case of no beat noise. In the case of beat noise the performance improved 1.5 times of simultaneous users of before and after inserting OHL. The performance marked use of symmetric prime-hop code.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.3
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• pp.281-289
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• 1994

This is a clinical study on 235 inpatients who sustained a total of 350 mandibular fractures and who were treated in our department during the period of Oug., 1989 through Dec., 1993. The results obtained are as follows : 1. The mumber of patients has not been increased year after year. In respect of incidence, there were the highest frequency as 67 patients(28.5%) in 1991 and the least frequency as 16 patients(6.8%) in 1989 and the highest frequency as 28 patients(11.9%) in October and the least frequncy as 12 patients(5.2%) in February. 2. The age frequency was the highest in the second decade(30.6%). The youngest patient was 8 months and the eldest patient was 80 years and mean age was 27.8 years. The ratio of men to Wemen was 4 : 1. 3. The most frequent cause was fall down as 86 patients(36.6%) and the next was fist blow 4 as 75 patients(31.9%), traffic accident as 56 patients(23.9%) in order. 4. The most common location was symphysis as 141 numbers(40.3%) and the next was condyle as 96 numbers(27.4%), angle as 94 numbers(26.8%), body as 14 numbers(4.0%) in order. The sum of fracture sites were 350 and there were 1.49 fracture sites per one patient and multiple fractures occured in 100 patients(40.5%) of the 235 patients. The ratio of Left to Right except for symphysis was 1.71 : 1. 5. Among the 333 associated injuries, facial laceration was 136(57.9%) and tooth injury was 58(24.7%) and extremity was 31(13.2%). 6. Among the 350 mandibular fractures, complications after treatment occured in 51(14.6%) and infection as 20(5.7%) was the most frequent complication. 7. In respect of treatment of mandibular fracture, close reduction was 64 patients(27.2%) and open reduction was 164 patients(69.8%) and other were 7 patients(3.0%) of all and so open reduction was the most common in type of treatment.

• Current Research on Agriculture and Life Sciences
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• v.9
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• pp.71-86
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• 1991

This study has tried to illuminate a shocking phenomenon, the import liberalization of agricultural products in the aspect of Consumer consciousness. It has been applied that Table Analysis by using computer programming for instance-MINITAB, and Correlation Analysis and Multiple Regression Analysis, things like that. The results of this study are as follows; 1. Comparing domestic and imported stuffs, Comsumers came to awareness that domestic products superior to foreign's in the cases of the degree of freshness, taste and pollution damage, in the meanwhile, inferior to the cases of price and wrapping. Food self-supplyment is considered as one of the most important things of all, moreover, by most comsumers and health food and conventional food are favored by high class people. 2. Bying imported stuffs could clearly be fatal blow to our agriculture is fully recognized among consumers, what is more, there would only be doomed to our agriculture, too. 3. The most mass-purchasing imported stuffs by consumers illustrates in order; Beef, Banana, Coffee and Tabacco etc. The most significant elements why consumers buy foreign product is that the prices of them are relatively lower than those of ours. Besides, the next causes lies to non-producing stuffs and curiosity. 4. It must've been generally conceived by most consumers that Open-the-market-policy has been progressed for USA's repression and our monopolistic capital. Therefore, they demand that our market should be contained against unadviciable wave, moreover, keep paying attention to the policy how it will work to protect Korean agriculture. 5. Consumer attitude toward buying imported agricultural products is double-faced, Never-buy occupied only 24.4 % among respondents, but overwhelming respondents say non-producing stuffs can be obtained selectively. In this case, however, never-buy-movement would be backed by consumers in proportion to their educational background. 6. Various consumer minds surrounding Open-the-market-situation, in the end, has been analized econometrics through eleven variables to approach accurate fulfillments.