• Korean Journal of Optics and Photonics
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• v.20 no.4
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• pp.241-248
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• 2009

We suggest a new method to determine the off-alignment error of the composite film, together with in-plane($R_{in}$) and out-of-plane retardation($R_{th}$) of the compensation film, simultaneously. The composite film consists of a polarizing film and a compensation film for improvement of viewing angle of a liquid crystal display. We regarded the compensation film as o-plate with its optic axis along an arbitrary direction. By using an extended Jones matrix method, the polarization characteristics of the composite film are examined. The calculated Fourier constants, ($\alpha$, $\beta$) curves of the composite film as the azimuth angle is varied at the incident angles of $0^{\circ}$ and $50^{\circ}$, respectively, are used to determine the axis misalignment, the tilt angle and the azimuth angle of the compensation film by adopting the linear regressional analysis technique. Since this method can be applied for the inspection of the composite film even after laminating the polarizing film and the compensation film, it will be useful for simplifying the manufacturing process and reducing the production cost of liquid crystal display panels.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.477-481
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• 2014

Flexible electronics have been to the fore because it is believed that flexibility can add incredible value such as light weight and mobility into the existing electronic devices and create new markets of large-area and low-cost electronics such as wearable eletronics in near future. Offset printing processes are regarded as major candidates for manufacturing the flexible electronics because they can provide the patterning resolution of micron-size effectively in large-area. In view of mechanics, the most important viewpoint in offset printing is how to achieve the synchronized movement of two contact surfaces in order to prevent slip between two contact surfaces and distortion of the blanket surface during ink transfer so that the high-resolution and good-overlay patterns can be printed. In this paper, a novel low-cost measurement method of the synchronization error using the motor control output signals is proposed and the compensation method is presented to minimize the synchronization error.

• Macromolecular Research
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• v.16 no.1
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• pp.6-14
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• 2008

Polypropylene (PP)-layered silicate nanocomposites were developed using a new processing method involving a supercritical carbon dioxide ($scCO_2$)-assisted co-rotating twin-screw extrusion process. The nanocomposites were prepared through two step extrusion processes. In the first step, the PP/clay mixture was extruded with $CO_2$ injected into the barrel of the extruder and the resulting foamed extrudate was cooled and pelletized. In the second step, the foamed extrudate was extruded with venting to produce the final PP/clay nanocomposites without $CO_2$. In this study, organophilic-clay and polypropylene matrix were used. Maleic anhydride grafted polypropylene (PP-g-MA) was used as a compatibilizer. This study focused on the effect of $scCO_2$ on the dispersion characteristics of the clays into a PP matrix and the rheological properties of the layered silicate based PP nanocomposites. The dispersion properties of clays in the nanocomposites as well as the rheological properties of the nanocomposites were examined as a function of the PP-g-MA concentration. The degree of dispersion of the clays in the nanocomposites was analyzed by X-ray diffraction and transmission electron microscope. Various rheological properties of the nanocomposites were measured using a rotational rheometer. In the experimental results, the $scCO_2$ assisted continuous manufacturing extrusion system was used to successfully produce the organophilic-clay filled PP nanocomposites. It was found that $scCO_2$ had a measurable effect on the clay dispersion in the polymer matrix and the melt intercalation of a polymer into clay layers.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.564-573
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• 2018

External environment of enterprises are rapidly changing brought about mainly by global competition, cost and profitability pressures, and emerging new technology. In particular, frequent change of customer requirements is a tough challenge to manufacturing company. To cope with these challenges, a production planning and scheduling (PP&S) function might be established to provide accountability for both customer service and operational efficiency. PP&S deals with short-term decision making in the production process of whole supply chain. The task of PP&S is to seek a balance between customer orders and limited resources. At present, many PP&S software solutions have been utilized in many enterprises to generate a realistic production plan and schedule efficiently. The aim of this paper is to analyze the PP&S functionalities and its system architecture from the perspective of SCM (Supply Chain Management), and propose the PP&S solution classification framework to facilitate the comparison among various solutions.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.137-146
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• 2017

For the competitive business environment under purchase dependence, this paper proposes a new approximate calculation of order fill rate which is a probability of satisfying a customer order immediately using the existing inventory. Purchase dependence is different to demand dependence. Purchase dependence treats the purchase behavior of customers, while demand dependence considers demand correlation between items, between regions, or over time. Purchase dependence can be observed in such areas as marketing, manufacturing systems, and distribution systems. Traditional computational methods have a difficulty of the curse of dimensionality for the large cases, when deriving the stationary joint distribution which is utilized to calculate the order fill rate. In order to escape the curse of dimensionality and protect the solution from diverging for the large cases, we develop a greedy iterative search algorithm based on the Gauss-Seidel method. We show that the greedy iterative search algorithm is a dependable algorithm to derive the stationary joint distribution of on-hand inventories in the retailer system by conducting a comparison analysis of a greedy iterative search algorithm with the simulation. In addition, we present some managerial insights such as : (1) The upper bound of order fill rate can be calculated by the one-item pure system, while the lower bound can be provided by the pure system that consists of all items; (2) As the degree of purchase dependence declines while other conditions remain same, it is observed that the difference between the lower and upper bounds reduces, the order fill rate increases, and the order fill rate gets closer to the upper bound.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.29-37
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• 2017

This papers focuses on remanufacturing processes in a closed loop supply chain. The remanufacturing processes is considered as one of the effective strategies for enterprises' sustainability. For this reason, a lot of companies have attempted to apply remanufacturing related methods to their manufacturing processes. While many research studies focused on the return rate for remanufacturing parts as a control parameter, the relationship with demand certainties has been studied less comparatively. This paper considers a closed loop supply chain environment with remanufacturing processes, where highly fluctuating demands are embedded. While other research studies capture uncertainties using probability theories, highly fluctuating demands are modeled using a fuzzy logic based ambiguity based modeling framework. The previous studies on the remanufacturing have been limited in solving the actual supply chain management situation and issues by analyzing the various situations and variables constituting the supply chain model in a linear relationship. In order to overcome these limitations, this papers considers that the relationship between price and demand is nonlinear. In order to interpret the relationship between demand and price, a new price elasticity of demand is modeled using a fuzzy based nonlinear function and analyzed. This papers contributes to setup and to provide an effective price strategy reflecting highly demand uncertainties in the closed loop supply chain management with remanufacturing processes. Also, this papers present various procedures and analytical methods for constructing accurate parameter and membership functions that deal with extended uncertainty through fuzzy logic system based modeling rather than existing probability distribution based uncertainty modeling.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.215-228
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• 2017

A new approach for measuring the specific fracture energy of concrete denoted modified disk-shaped compact tension (MDCT) test is presented. The procedure is based on previous ideas regarding the use of compact tension specimens for studying the fracture behavior of concrete but implies significant modifications of the specimen morphology in order to avoid premature failures (such as the breakage of concrete around the pulling load holes). The manufacturing and test performance is improved and simplified, enhancing the reliability of the material characterization. MDCT specimens are particularly suitable when fracture properties of already casted concrete structures are required. To evaluate the applicability of the MDCT test to estimate the size-independent specific fracture energy of concrete ($G_F$),the interaction between the fracture process zone of concrete andthe boundary of theMDCTspecimens at the end of the test is properly analyzed. Further, the experimental results of $G_F$ obtained by MDCT tests for normal- and high-strength self-compacting concrete mixes are compared with those obtained using the well-established three-point bending test. The procedure proposed furnishes promising results, and the $G_F$ values obtained are reliable enough for the specimen size range studied in this work.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Journal of the Korean Society of Costume
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• v.65 no.2
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• pp.125-143
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• 2015

This study is to propose an 'education-training-certificate of qualification' design of fashion accessories production, which can be applied to education in universities and individuals. It is based on the National Competency Standards (NCS), which was developed through the '2013 National Competency Standards Development Project' for the fashion accessories production. FGI (Focus Group Interviews), which is a research methodology, is carried out on target groups of educational experts and specialists in the field of fashion accessories production. Through this, five courses were suggested; first, 'fashion accessories design' course was proposed for the education and training of 'design development' and 'development of raw materials'. Secondly, 'fashion product production' course was proposed for the education and training of 'production of samples'. Thirdly, 'fashion product manufacture and planning' course was proposed for the competency element units: 'calculation of cost', 'determination of mass production model and price', 'planning of the main manufacturing process' and 'ordering of raw materials'. Lastly, 'mass production of fashion products' course and the 'field practice of fashion product manufacture' course were proposed for the competency element units: 'planning for mass production', 'preparation for mass production', 'mass production' and 'inspection of completed products'. In addition, a new certificate of 'technician of fashion accessory production' was proposed in order to test qualified skills for the fashion accessories production. The test is composed of a written examination of short-answer questions, technical drawing and production.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.116-121
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• 2009

Thermosonic flip chip bonding is an important technology for the electronic packaging due to its simplicity, cost effectiveness and clean and dry process. Mechanical properties of the horn and the shank, such as the natural frequency and the amplitude, have a great effect on the bonding capability of the transverse flip chip bonding system. In this research, two kinds of study are performed. The first is the new design of the clamp and the second is the effect of tolerance parameters to the performance of the system. The clamp with a bent shape is newly designed to hold the nodal point of the flip chip. The second is the effect of the design parameters on the vibration amplitude and planarity at the end of the shank. The variation of the tolerance parameters changes the amplitude and the frequency of the vibration of the shank. They, in turn, have an effect on the quantity of the plastic deformation of the gold ball bump, which determined the quality of the flip chip bonding. The tolerance parameters that give the great effect on the amplitude of the shank are determined using Taguchi's method. Error of set-up angle, the length and diameter of horn and error of the length of the shank are determined to be the parameters that have peat effect on the amplitude of the system.