• Journal of Korean Institute of Industrial Engineers
• /
• v.24 no.4
• /
• pp.649-660
• /
• 1998

Steel making in Mini Mill consists of three major processing stages: molten steel making in an electric arc fuenace, slab casting in a continuous caster, and hot rolling in a finishing mill. Each processing stage has its own lot grouping criterion. However, these criteria in three stages are conflicting with each other. Therefore, delveloping on efficient lot grouping algorithm to enhance the overall productivity of the Mini Mill is an extremely difficult task. The algorithm proposed in this paper is divided into three steps hierarchically: change grouping, cast grouping, and roll grouping. An efficient charge grouping heuristic is developed by exploiting the characteristics of the orders, the processing constraints and the requirements for the downstream stages. In order to maximaize the productivity of the continuous casters, each cast must contain as many charges as possible. Based on the constraint satisfaction problem technique, an efficient cast grouping heuristic is developed. Each roll consists of two casts satisfying the constraints for rolling. The roll grouping problem is formulated as a weighted non-bipartite matching problem, and an optimal roll grouping algorithm is developed. The proposed algorithm is programmed with C language and tested on a SUN Workstation with real data obtained from the H steel works. Through the computational experiment, the algorithm is verified to yield quite satisfactory solutions within a few minutes.

• Journal of Korea Foundry Society
• /
• v.28 no.3
• /
• pp.113-118
• /
• 2008

A new approach of producing martensitic structure for guide-roll materials was developed using centrifugal casting instead of classic overlay welding process. Centrifugal casting offered a simpler process, fewer defects and even microstructures. Especially in terms of thermal fatigue cracking which usually occurs in the HAZ of welding beads of used continuous caster guide roll materials made by overlay welding process. A typical tensile strength of 1,600 MPa was obtained by this process and was higher than typical tensile strength($800{\sim}1,200\;MPa$) with overlay welding technique. Tempering at $400{\sim}550^{\circ}C$ for 2 hrs was observed to have significant precipitate hardening effect which increases strength and elongation. Nitrogen content from the Cr-N input in the casting process was found to have positive contribution to decrease the volume fraction of ${\delta}$-ferrite which directly corresponds to increasing strength of the roll materials.

• Korean Journal of Metals and Materials
• /
• v.48 no.5
• /
• pp.387-393
• /
• 2010

High-strength aluminum alloy sheets with high magnesium contents were fabricated by a strip caster equipped with an asymmetric nozzle, which has been proven to be effective for reducing surface defects and internal segregation. 4 mm thick as-cast sheets consisting of fine dendrites and minor $Al_{8}Mg_{5}$ segregation were hot-rolled successfully to 1 mm sheets and subsequently annealed at various temperatures. The sheet revealed the tensile strength and elongation of 306 MPa and 34%, respectively, when it was rolled at 250${^{\circ}C}$ and subsequently annealed at 475${^{\circ}C}$, which exhibits the feasibility of the practical application for autobodies. The observed mechanical properties were explained on the basis of the microstructural characteristics of the alloy sheets.

• The Journal of Internal Korean Medicine
• /
• v.29 no.2
• /
• pp.348-358
• /
• 2008

Objective : The aim of this experimental study was to investigate the anti-diarrhea effects of Jisa-tang using mice and guinea pigs. Methods : We feed Jisa-tang to mice and guinea pigs to investigate its effects for anti-diarrhea action. We observed its actions on gastrointestinal smooth muscles, on the transportability of small and large intestines, on diarrhea induced by castor oil and magnesium sulfate, and on enteropooling by castor oil and prostaglandin $E_2(PGE_2)$. Results : 1. Jisa-tang showed alleviation, depending on the density, only on the contraction of mice's gastrointestinal smooth muscles induced by histamine. 2. The transportability of the small intestine was not significantly constrained by Jisa-tang. However, the enhancement of pyridostigmine-induced transportability of he small intestine was significantly constrained in the group administered 900mg/kg of Jisa-tang (p<0.05). 3. The transportability of large intestine was significantly constrained in the group administered 1,800mg/kg of Jisa-tang. 4. Jisa-tang showed significant anti-diarrhea effects on diarrhea induced by castor oil and by $MgSO_4$ in the group administered 1,800mg/kg of Jisa-tang. 5. Significant reduction of effects of enteropooling induced by caster oil and by prostaglandin $E_2$ were observed only in the group administered 1,800mg/kg of Jisa-tang. Conclusions : We conclude that Jisa-tang has advantageous effects on drug-induced diarrhea and will contribute to the development of diarrhea treatment through further related studies.

• Proceedings of the Korea Contents Association Conference
• /
• 2006.11a
• /
• pp.856-859
• /
• 2006

Patient's position who muscle ache curer for hospital undergoes person entrance and treatment that take advantage of biological, physical force of low frequency and it is equipment that treat body muscle ache, but use equipment when use patient into compensation in hospital specially, that consider everybody is important first of all. This research question investigation with market survey of old product enforce because preference degree reflected officer a result and apply opinion tuned with product development connection engineers on DESIGN direction via typical product design development process close. This curer development research analyzed data involved directly taking advantage of FGI techniques with literature investigation collection. Investigation examined laying stress on muscle ache curer for hospital and a nurse than a doctor answered on question and purchase selection criterion or price portion to user focus. Direct market survey research that see item indicated by competition four provision shortcomings consequently in NEW MODEL development hereafter supplement and expectation. by contributing greatly in M/S security strategy hereafter because design development consisted for side that improve.

• Safety and Health at Work
• /
• v.7 no.3
• /
• pp.237-243
• /
• 2016

Background: This study examined the relationship between interhandle distances and upper limb exertion during simply pushing and pulling of a cart with four swivel wheels, defined by a roll box pallet (RBP) in a Japanese industrial standard. Methods: Six healthy young male participants were asked to push and pull an RBP at a distance of 5.2 m under six conditions corresponding to different interhandle distances (40 cm, 60 cm, and 80 cm) and weights (130 kg and 250 kg). The upper limb exertion was studied by shoulder abduction and flexion, and elbow flexion, as well as surface electromyogram (EMG) in shoulder extensor, and elbow flexor and extensor. Participants were required to provide subjective evaluations on operability after each trial. Results: Subjective operability indicated that a narrower interhandle distance had a better operability for pushing. Interhandle distance was also related to upper limb exertion especially for pushing. A narrow interhandle distance caused smaller shoulder adduction but larger elbow flexion. The normalized EMG data revealed that muscular activity became smaller with a narrow interhandle distance in shoulder extensor. During the pulling task, elbow flexion was smaller at a narrow interhandle distance, although subjective operability and normalized EMG were not significantly varied. Conclusion: A wider interhandle distance, such as 80 cm, was not suitable in the forwardbackward movement of the RBP. Therefore, this study concluded that an interhandle distance of 40 cm would be suitable for pushing and pulling an RBP to protect the workers' hands against the risk of injury by installing inner handles.

• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.227-232
• /
• 2008

In this research, organic extracts from roots of platycodon grandiflorum was tested to see the possibility for cosmetic natural surfactant. Interfacial properties of extracts of Platycodon grandiflorum was checked for interfacial tension, forming force, dispersion force, emulsion force, emulsion activity, and emulsion stability. At 0.005 wt% concentration, the interfacial tension against the caster oil was 11.5 dyn/cm which was lower than that of Tween 40 and quillaja bark. Extracts of Platycodon grandiflorum showed excellent emulsification activity and stability for cosmetic oils such as olive oil, soybean oil, and canola oil. In patch test using 2-5% of the extract and glycerin, the extract showed mild skin irritation. From the experiment, the extracts of platycodon grandiflorum root showed good interfacial properties as a cosmetic agent with minor skin irritation.

• Applied Chemistry for Engineering
• /
• v.28 no.3
• /
• pp.326-331
• /
• 2017

Castor oil can be used as a useful raw material for chemical industries such as intermediates of surfactants through hydrogenation reaction. In this study, effects of the preparation method and pretreatment condition on the nickel catalyst for the hydrogenation of castor oil were investigated. The nickel catalyst was supported on the silica carrier by the precipitation method with different Ni contents, solution pH values, and precipitants. Repeated pretreatments of oxidation and reduction cycles were then carried out. The activity of the nickel catalyst was measured by comparing the iodine value of the castor oil. The dispersion of nickel on the catalyst was analyzed by X-ray diffraction (XRD), $N_2$ adsorption-desorption, and transmission electron microscopy (TEM). The activity of nickel catalyst was also compared by CO oxidation experiments. The redispersion of nickel occurred on the silica by repeated oxidation and reduction cycles, and this effect contributed to promoting the castor oil hydrogenation activity.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.25 no.5
• /
• pp.338-344
• /
• 2016

Recent trends in transport system for carrying heavy freight are that demands of a high efficiency, economic efficiency, convenience and safety are increased. Conventional transport systems were poor in transport efficiency and economic efficiency. And Safety problems can be caused to products and workers. In order to overcome these problems, an air cushion transport device with a high-pressure air is required. The air cushion transporter is a device for reducing the frictional force of floor surface and lifting the heavy freight by spraying the high-pressure air to the floor. Technology to float and transfer freight using high-pressure air is very convenient and initial cost can be reduced. In this paper, the study on the levitation performance and transport efficiency of air cushion transport system is conducted and verified that air cushion transporter has a significantly higher transport efficiency than conventional heavy handling systems.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.22 no.5
• /
• pp.570-576
• /
• 2012

In this research a moving platform for a mobile robot which can run with upright posture is proposed. It is able to stand with standing arms and run uprightly based on an inverted pendulum mechanism. Conventional mobile robots generally may equip 4 wheels or 3 wheels including a caster and have good statistic stability. They need a steering mechanism to choose which way to go since they have a square or rectangular configuration with multiple wheels. When a mobile robot meets a sharply perpendicular and narrow crossroad, it may need a special steering scheme such as going forward and backward repeatedly or it sometimes cannot even pass through the crossroad because of its size. The proposed moving platform for a mobile robot changes to a upright posture which has a small planar area and is able to pass through the crossroad. We propose a moving platform for a mobile robot with a inverted pendulum mechanism and standing arms which can make the mobile robot upright.