• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1451-1458
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• 2001

The effects of a specularly reflecting surface on the wall heat flux and medium temperature distribution are studied. The system is an infinite square duct enclosing an absorbing and emitting medium. The walls are opaque, and black or gray. The walls emit diffusely but reflect diffusely or speculary. Heat is transferred by the combined effect of conduction and radiation. The radiative heat transfer is analyzed using direct discrete-ordinates method. The parameters under study are conduction, to radiation parameter, optical depth, wall emissivity, and reflection characteristics. The specular reflection and diffuse reflection show sizeable differences when the conduction to radiation parameter is less than around 0.01. The differences appear only either on the side wall heat flux or on the medium temperature profiles for the range of this study. The differences on the side wall heat flux are observed for optical thickness less than around 0.1 However the differences on the medium temperate profiles are found for optical thickness greater than around 1. The difference increase with increasing reflectance. The specular reflection increases the well heat flux gradient along the side wall.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.3
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• pp.52-59
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• 1987

The flatness of a precision surface plate is generally measured by using precision angular measuring instruments such as laser interferometers, autocollimators and electronic levels. Since these instruments are expensive and measurement procedures are complex, such methods are not widely used in industries. In this study, an electronic micrometer that is easy to use and inexpensive to produce was developed in order to solve this problem. The flatness of a black granite surface plate, measured using this device was compared with the values obtained by using the conventional three methods. The results were consistent within ${\pm}1{\mu}m$. It proves that the flatness measuring method using electronic micrometers can be utilized for quantitative measurement. An accessory device that can improve the precision of measurement by attaching to the electronic micrometer was also designed and fabricated.

• Tribology and Lubricants
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• v.32 no.2
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• pp.44-49
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• 2016

Diamond mechanical polishing (DMP) is a crucial process in a sapphire wafering process to improve flatness and achieve the target thickness by using free abrasives. In a DMP process, material removal rate (MRR) is a key factor to reduce process time and cost. Controlling mechanical parameters, such as velocity and pressure, can increase the MRR in a DMP process. However, there are limitations of using high velocities and pressures for achieving a high MRR owing to their side effects. In this paper, we present the lapping characteristics and improvement of MRR by using a fixed abrasive plate through an experimental study. The change in MRR as a function of velocity and pressure follows Preston's equation. The surface roughness of a wafer decreases as the plate velocity and pressure increases. We observe a sharp decrease in MRR over the lapping time at a high velocity and pressure in the velocity and pressure test. An analysis of surface roughness (Rq and Rpk) indicates that wear of abrasives decreases the MRR sharply. In order to investigate the effect of abrasive wear on the MRR, we utilize a cutting fluid and a rough wafer. The cutting fluid delays the wear of abrasives resulting in improvement of MRR drop. The rough wafer maintains the MRR at a stable rate by self-dressing.

• Tribology and Lubricants
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• v.32 no.2
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• pp.50-55
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• 2016

Recently, a double-side machining process has been adopted in fabricating a sapphire glass to enhance the manufacturability. Double-side lap grinding (DLG) is one of the emerging processes that can reduce process steps in the fabrication of sapphire glasses. The DLG process uses two-body abrasion with fixed abrasives including pallet. This process is designed to have a low pressure and high rotational speed in order to obtain the required material removal rate. Thus, the temperature is distributed on the DLG platen during the process. This distribution affects the shape of the substrate after the DLG process. The coolant that is supplied into the cooling channel carved in the base platen can help to control the temperature distribution of the DLG platen. This paper presents the results of computational fluid dynamics with regard to the heat transfer in a DLG platen, which can be used for fabricating a sapphire glass. The simulation conditions were 200 rpm of rotational speed, 50℃ of frictional temperature on the pallet, and 20℃ of coolant temperature. The five cases of the coolant flow rate (20~36 l/min) were simulated with a tetrahedral mesh and prism mesh. The simulation results show that the capacity of the generated cooling system can be used for newly developed DLG machines. Moreover, the simulation results may provide a process parameter influencing the uniformity of the sapphire glass in the DLG process.

• Tribology and Lubricants
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• v.32 no.2
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• pp.67-71
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• 2016

This study investigates the characteristics of the sapphire wafer chemical mechanical polishing (CMP) process. The material removal rate is one of the most important factors since it has a significant impact on the production efficiency of a sapphire wafer. Some of the factors affecting the material removal rate include the pressure, platen speed and slurry. Among the factors affecting the CMP process, we analyzed the trends in the material removal rate and surface roughness, which are mechanical factors corresponding to both the pressure and platen speed, were analyzed. We also analyzed the increase in the material removal rate, which is proportional to the pressure and platen speed, using the Preston equation. In the experiment, after polishing a 4-inch sapphire wafer with increasing pressure and platen speed, we confirmed the material removal rate via thickness measurements. Further, surface roughness measurements of the sapphire wafer were performed using atomic force microscopy (AFM) equipment. Using the measurement results, we analyzed the trends in the surface roughness with the increase in material removal rate. In addition, the experimental results, confirmed that the material removal rate increases in proportion to the pressure and platen speed. However, the results showed no association between the material removal rate and surface roughness. The surface roughness after the CMP process showed a largely consistent trend. This study demonstrates the possibility to improve the production efficiency of sapphire wafer while maintaining stable quality via mechanical factors associated with the CMP process.

• The Journal of the Convergence on Culture Technology
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• v.2 no.4
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• pp.23-29
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• 2016

The purpose of this study is to study the laws of storage and utilization in various perspectives in order to maximize the storage of knowledge and to use stored knowledge. In other words, it analyzes the relationship rules in five viewpoints of 'human and knowledge', 'human and goods', 'the law of exact intersection with humans', 'human architecture formation process', 'human and knowledge' This course studies how to maximize the relationship rules between knowledge storage and utilization through knowledge management, intuition, rapid decision-making, and understanding of various knowledge. In order to maximize the value of knowledge in the organization, the knowledge management system obtained in this way systematically organizes various information about the knowledge creation of the members and distributes it to all employees to use it for their work. As an information management infrastructure, To effectively manage the various knowledge and know-how accumulated in the organization and to share them with each other.

• Tribology and Lubricants
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• v.32 no.4
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• pp.119-124
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• 2016

In the sapphire wafering process, lapping is a crucial operation in order to reduce the damaged layer and achieve the target thickness. Many parameters, such as pressure, velocity, abrasive, slurry and plate, affect lapping characteristics. This paper presents an experimental investigation on the effect of the plate groove on the material removal rate and roughness of the wafer. We select the spiral pattern and rectangular type as the groove shapes. We vary the groove density by controlling the groove shape dimension, i.e., the groove width and pitch. As the groove density increases to 0.4, the material removal rate increases and gradually reaches a saturation point. When the groove density is low, the pressing load is mostly supported by the thick film, and only a small amount acts on the abrasives resulting to a low material removal rate. The roughness decreases on increasing the groove density up to 0.3 because thick film makes partial participations of large abrasives which make deep scratches. From these results, we could conclude that the groove affects the contact condition between the wafer and plate. At the same groove density, the pitch has more influence on reducing the film thickness than the groove width. By decreasing the groove density with a smaller pitch and larger groove width, we could achieve a high material removal rate and low roughness. These results would be helpful in understanding the groove effects and determining the appropriate groove design.

• Journal of Service Research and Studies
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• v.9 no.2
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• pp.1-15
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• 2019

This study analyzed the service philosophy of Eastern mainstream thought in order to establish a service philosophy. Following a prior study the "study of the service philosophy of major korean ideology", we explored the service philosophy of the Eastern mainstream ideology of China and India and it's coherence. The existing basic structure and operational model of service philosophy were presented in depth and the service philosophy of Oriental mainstream thought was derived. The philosophy of service can be presented as an idea of the structure of the service and as an idea of the operation of the service. It suggested compatibility of the service philosophy of Asian mainstream ideas, and analyzed them mainly in China and India. Indian ideas revolved around the ancient philosophy of Veda, Upanishads philosophy, and representative Buddhist philosophy. It also showed that a major trend of mainstream ideas in China and India was found to be compatible with the service philosophy. Follow-up studies are needed to further refine the structure of service philosophy and develop the principles of operation into larger ideas in the future, and a study of conformity of service philosophy in representative Western ideas, focusing on Greek, Roman, and German philosophy, is also required. Ultimately, it is necessary to establish a service philosophy as an ideological base that drives future economic and social development.

• Journal of Service Research and Studies
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• v.9 no.1
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• pp.1-16
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• 2019

This study analyzed Korean representative ideology to establish a service philosophy. As a follow - up study of the service philosophy consistency study of the Korean original idea, we searched for the coherence as the philosophy of the service age in the Korean representative ideology. The basic structure and operation model of service philosophy are presented, and the service philosophy of major korean ideology is derived. The philosophy of service can be presented by the structure of service and the operation of service. The essential characteristics of the service are relationship, interactivity, horizontality, and harmony, and the service structure that reflects this is the coexistence of products and services. Based on the discussion on the structure and operation of the service philosophy, the service philosophy synthesis of Korean representative ideology is presented. From the Silla era to the Koryo dynasty, the essence of Korean Buddhism thought is in line with the service philosophy, and it was found that Toegye and Yulgok to Dasan's thoughts are also consistent with service philosophy. In the future, we need further studies to refine the structure and operational principles of the service philosophy and to develop it into a big idea. In addition, it is necessary to follow up the service philosophy of Oriental representative ideology centering on Chinese and Indian philosophy. Ultimately, it is necessary to establish a service philosophy as the main philosophical thought and to establish a service philosophy as a desirable future economic and social philosophy.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.107-117
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• 2019

Because shipbuilding is single-product production with limited resources, production management technology is essential to manage the resources effectively and maximize the productivity of ship-process. Therefore, many shipbuilding companies are conducting research on ship production plan and process considering various constraints in the field by applying modeling and simulation. However, it is difficult to provide accurate production plan on sudden schedule and process changes, and to understand the interconnectivity between the processes that produce blocks in existing research. In addition, there are many differences between the production planning and field planning because detailed processes and quantity of blocks can not be considered. In this research, we propose the integrated process-based modeling method considering process-operation sequences, BOM(Bill of materials) and resource constraints of all the scheduled blocks in the indoor system. Through the integrated process-based model, it is easy for the user to grasp the assembly relationship, workspace and preliminary relationship of assembly process between the blocks in indoor system. Also, it is possible to obtain the overall production plan that maximizes resource efficiency without the separate simulation and resource modeling procedures because resource balancing that considers the amount of resource quantity shared in the indoor system is carried out.