• Journal of Power Electronics
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• v.6 no.2
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• pp.178-185
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• 2006

Recently, the demand for the development of high quality and high-speed laser printers and efficient power utilization has required. Among complicated electro-mechanic devices in laser printers, the toner-fusing unit consumes above 90[%] of all electrical energy needed for printing devices. Therefore, the development of a more effective energy-saving toner fusing process becomes a significant task in great demand. Generally, there are several ways to implement a fusing unit. Among them this paper presents a new induction heating method. The proposed induction heating method enables the increase of coupling coefficient between heating coil and heat roller which also increases total energy transfer efficiency. Therefore, the proposed IH (Induction Heating) inverter system provides very fast W.U.T. (Warm UP Time) as well as higher efficiency. Through experimental results, the proposed control system is verified.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.73-82
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• 2016

PURPOSES: The national highways and expressways in Korea constitute a total length of 17,951 km. Of this total length of pavement, the asphalt pavement has significantly deteriorated, having been in service for over 10 years. Currently, hot in-place recycling (HIR) is used as the rehabilitation method for the distressed asphalt pavement. The deteriorated pavement becomes over-heated, however, owing to uncontrolled heating capacity during the pre-heating process of HIR in the field. METHODS: In order to determine the appropriate heating method and capacity of the pre-heater at the HIR process, the heating temperature of asphalt pavement is numerically simulated with the finite element software ABAQUS. Furthermore, the heating transfer effects are simulated in order to determine the inner temperature as a function of the heating system (IR and wire). This temperature is ascertained at $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$, and $800^{\circ}C$ from a slab asphalt specimen prepared in the laboratory. The inner temperature of this specimen is measured at the surface and five different depths (1 cm, 2 cm, 3 cm, 4 cm, and 5 cm) by using a data logger. RESULTS: The numerical simulation results of the asphalt pavement heating temperature indicate that this temperature is extremely sensitive to increases in the heating temperature. Moreover, after 10 min of heating, the pavement temperature is 36%~38% and 8%~10% of the target temperature at depths of 25 mm and 50 mm, respectively, from the surface. Therefore, in order to achieve the target temperature at a depth of 50 mm in the slab asphalt specimen, greater heating is required of the IR system compared to that of the gas. CONCLUSIONS : Numerical simulation, via the finite element method, can be readily used to analyze the appropriate heating method and theoretical basis of the HIR method. The IR system would provide the best heating method and capacity of HIR heating processes in the field.

• Korean journal of food and cookery science
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• v.30 no.1
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• pp.51-63
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• 2014

A microbiological quality evaluation on cooked food, food materials and cooking equipment was conducted in 14 school food services in Changwon area, South Korea for Ojingeochaesomoochim (vegetable salad with blanched squid) which went through cooking process after heating treatment. Only 5 schools out of the 14 (35.7%) observed the sanitization criteria of the Korean School Meals Sanitization Management for raw vegetables (concentration of chlorine solution: 100ppm, immersion time of sanitizing: 5 min). The acceptance rates regarding the microbial standards for Korean school meals showed improvement before and after of sanitization: for onions 57.1% vs 71.4%; cucumber 42.9% vs. 78.6%. However, garlic showed adverse sanitizing effect as the acceptance rate went down from 42.9% to 35.7%. Blanched squid and red pepper paste was acceptable in all 14 schools (100%), while squid seasoned with red pepper powder was acceptable in only 42.9% of the schools. Microbial results for knives, cutting boards, mixing bowls were satisfactory, however 35.7% of sanitary gloves that were put on right before the seasoning showed poor sanitization, and this indicated high probability of cross-contamination from the gloves. We calculated that 57.1% of the cooked foods were in accordance with the microbial standards for Korean school meals. Therefore, it is strongly recommended to have verification process, especially on the effectiveness of sanitization of raw vegetables, in cooking foods through cooking process after heating treatment in HACCP system of school food service.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.942-945
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• 2005

Micron-sized metal wires are widely used in industries such as filtration, catalyst and composite materials, etc. In the wire drawing process, the die that is used conventionally is an effective and, at the same time, sensitive component. However, a typical array of the dies has caused many problems in the wire drawing process, e.g., large frictional force on the interface between wire and the resulting high heat generation, precise adjustment of the dies, extended cooling system, die abrasion, etc.. Because of these problems, there have been many works that are aiming at improving the efficiency of wire drawing process by analyzing the die geometry and by applying advanced die material to prolong the die life or even at developing a dieless wire drawing system. This paper is dealing with developing a new wire drawing system that is applicable to reduce the wire drawing steps with high draw ratio. The new wire drawing system does not use the dies, but use the self-induced heater that works on the basis of the resonant phenomenon of wire material. The electromagnetic wave is the heating source. The results of the study on the diameter reduction and microwave flow analysis show that the heating effectiveness of the wire is influenced by the energy distribution in the microwave propagation chamber. We can obtain diameter-reduced wires by using microwave in the dieless drawing process. Microwave as a heating source is capable of producing wires without applying dies in wire drawing process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.7
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• pp.809-815
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• 2014

The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.63-73
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• 2015

This study was carried out to evaluate the change of heating value of cow manure by applying pre-treatment process. Three types of treatment precess; Composting, Dry anaerobic digestion and Physical compression were applied as a pre-treatment method. Composting and anaerobic digestion of cow manure were cause of caloric value reduction of the cow manure. The heating value of cured compost was 5% lower than that of initial composting material. The heating value of dry anaerobic digestion residue was 25.7% lower than that of fresh cow manure. By physical compression of cow manure, heating value and VS/TS ratio (Volatile solids/Total solids ratio) of compressed cow manure were higher than that of fresh cow manure. On the other hand, heating value and VS/TS ratio of leachate generated by compression process were lower than those of fresh cow manure.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.1-10
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• 2020

This study deals with the fabrication and thermal characterization of planar heating elements attached to the backside of the reflector used in the electrodeless lamp of a freezer. We tried to solve the problem of the local heat generation of the linear heating element that occurs about 50℃. The homogeneous dispersion and manufacturing excellence of the planar heating element produced were confirmed through SEM and EDS. In addition, the test specimens was prepared according to the change in the ratio of carbon fiber to the basis weight of the planar heating element, and a sample having a basis weight of 50g/㎡ having a content ratio of carbon fiber of 70% was selected. That sample showed low surface resistance of 4.3Ω/sq and high temperature of about 81℃ at 6V. Durability was confirmed by performing repeated bending evaluation of 3000 cycles for the sample. Large area test specimens were prepared to be applied to the actual reflector, insulated by EVA film and analyzed for their thermal characteristics. From 13V application, the temperature of the linear heating element was higher than 50℃ and the average temperature of 68℃ was maximum at 18V.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.1-7
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• 2021

Demand for Ti-6Al-4V alloy is increasing in various industries because of its superior strength to weight and high-temperature strength properties. However, due to its low formability at room temperature, it is formed at high temperature, where its productivity and efficiency are low. The current high-temperature forming method has many limitations because it involves heating the specimen by heating the lower mold. It is expected that a process using high frequency induction heating, which can locally heat the product, can improve its productivity. In addition, time and cost can be saved if the process is simulated in advance with a reliable analysis. In this paper, we verified the reliability of the analysis by comparing the result of heating the specimen to 850 ℃ by high frequency induction heating and the temperature obtained through the co-simulation analysis.

• Textile Coloration and Finishing
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• v.20 no.3
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• pp.25-30
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• 2008

In order to examine the availability of a heating process for persimmon dyeing, the cotton fabrics treated with various concentrations of persimmon extracts were heated at various temperatures and times. The raw and fermented persimmon extracts were used for the coloration. For both extracts, the color strength of fabrics was. increased with the increase of coloration temperature, time, and concentration of the extracts. Considering the practical aspects. and color strength, the temperature around $200^{\curc}C$ and the time longer than 60 minutes can be determined as the. optimum coloration conditions of persimmon extracts onto cotton fabrics. However, somewhat loss of strength by the hearing process seems to be inevitable. The color fastness to washing was excellent for both color change and staining showing a rating of 5.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.17-22
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• 2004

In the study, we have developed a straightening system for 304 micro wires that are normally used in the medical and semi-conductor fields. To apply heat to the micro wires, we introduced the direct wire heating method which generates the thermal energy by the electrical resistance of the wire itself. To avoid the deterioration of the wire surface by the environment, such as the oxidation or the hydration, the $N_2$ gas was filled in the glass pipe in which the straightening process was being performed. A precision tension meter was also attached to control the tension of the wire during the heating and straightening process. In order to control the straightening process, several experimental investigations with varying the tension, the feeding velocity and the temperature (current) was carried out. As a result of experiments, we obtained the optimal processing conditions satisfying the straightness requirement of the micro wires.