• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.2
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• pp.65-73
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• 2008

The characterization process for the accurate color reproduction in mobile phone with camera and LCD is popular. The camera and LCD characterization, gamut mapping process is necessary to map the camera's input color stimulus, CIEXYZ value, into the LCD's output color stimulus. Each characterization is the process estimating the relation between input and output signals. In case of LCD, because of output device, the output color stimulus for the arbitrary input signal can be measured by spectro-radiometer However, in the camera, as the input device, the characterization is an inaccurate and needs the manual works in the process obtaining the output signal because the input signal can not be generated. Moreover, after gamut mapping process, the noise is increased because the optimized gamma tone curve of camera for the noise is distorted by the characterization. Thus, this paper proposed the system of obtaining the output signal of camera and the method of gamma correction for the noise. The camera's output signal is obtained by RGB values of patches from captured the color chart image. However, besides the illumination, the error for the location of the chart in the viewfinder is generated when many camera modules are captured the chart. The method of correcting the position to correct the error from manual works. The position of camera is estimated by captured image. This process and moving of camera is accomplished repeatedly, and the optimized position can be obtained. Moreover, the lightness curve of camera output is corrected partly to reduce the noise from the characterization process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.12-18
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• 2008

Ag paste was employed for source and drain electrode of OTFTs and for the data metal lines of OTFT-OLED array on PC(polycarbonate) substrate. We tested two kinds of Ag-pastes such as pastes for 325 mesh and 500 mesh screen mask to examine the pattern ability and electrical performance for OTFTs. The minimum feature size was 60 ${\mu}m$ for 325 mesh screen mask and 40 ${\mu}m$ for 500 mesh screen mask. The conductivity was 60 $m{\Omega}/\square$ for 325 mesh and 133.1 $m{\Omega}/\square$ for 500 mesh. For the OTFT performance the mobility was 0.35 $cm^2/V{\cdot}sec$ and 0.12 $cm^2/V{\cdot}sec$, threshold voltage was -4.7 V and 0.9 V, respectively, and on/off current ratio was ${\sim}10^5$, for both screen masks. We applied the 500 mash Ag paste to OTFT-OLED array because of its good patterning property. The pixel was composed of two OTFTs and one capacitor and one OLED in the area of $2mm{\times}2mm$. The panel successfully worked in active mode operation even though there were a few bad pixels.

• Korean Institute of Interior Design Journal
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• v.20 no.4
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• pp.174-182
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• 2011

This study analyzed visitors' behaviors in the viewpoint of Attraction Power and Holding Power of exhibits on the basis of exhibition layout of real science museums. Through the analysis, the study grasped efficiency of analysis index and exhibition environment elements which might have an effect on planning the exhibition space of a large-scale museum and producing detailed ranges of exhibition. The main indicators used are: 1. Attraction Power: it indicates the relative incidence of people who have stopped in front of an object/exhibit during the exhibition tour. It is calculated by dividing the number of people who stop by the total number of people who have visited the museum or gallery. 2. Holding Power: it measures the average time spent in front of an information/communication element. It is calculated by dividing the average time of stay by the time "necessary" to read an element. As a result of analyzing the exhibition areas of National Science Museum (Daejeon) and National Museum of Emerging Science and Innovation(Tokyo), the Holding Power was found to be relatively lower than the Attracting Power. This means that 3.5 out of 10 visitors stop in front of the exhibit in 6 exhibition areas, and among these, only 1/10 is used when compared to the user required time of the exhibits. In other words, like the method of deriving an analysis index, the stage of viewing can be categorized as Attracting Power and Holding Power, and because the stage from Attracting Power to the stage of Holding Power are strongly linked, it shows that it is not easy to display a meaningful result. Except, the general distribution of Attracting Power was shown to be high from the entrance area of the exhibition hall based on the standard of viewing sequence. Also, the Holding Power became sequentially lower according to the sequence of exhibition viewing and displayed a meaningful interrelationship with the distribution ratio of island exhibits. In the case of island exhibition method, it is less influenced by the movement flow of visitors when compared to the wall type method of exhibition and can be understood as an exhibition method that provides spatial chances enabling stopping and viewing.

• Journal of Distribution Science
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• v.13 no.3
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• pp.69-77
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• 2015

Purpose - The purpose of this study is to examine whether the cash policies of retail firms listed on Korean stock markets are consistent with the evidence provided in the study of Almeida et al. (2004). Liquidity management is an important issue for financially constrained firms relative to financially unconstrained firms. Because there are few sources of external funding, the optimal liquidity policies of financially constrained firms should reflect their own earnings or cash inflows to create opportunities for current and future real investments. According to this simple idea, we estimate the sensitivity of cash to cash flows and simply check whether the estimated sensitivity to cash flows of the cash retained by constrained retail firms is greater than that of the cash retained by unconstrained retail firms. Through this work, we aim to explain why the cash policies of the retail firms listed on the Korean stock markets differ from those of listed manufacturing enterprises. Research design, data, and methodology - To explain a firm's cash holdings, we use only three explanatory variables: earnings before interest and taxes (EBIT), Tobin's q, and size. All the variables are defined as the value of the numerator divided by aggregate assets. Thanks to this definition, it is possible to treat all the sample firms as a single large firm. The sample financial data for this study are collected from the retail enterprises listed on the KOSPI and KOSDAQ markets from 1991 to 2013. We can obtain these data from WISEfn, the financial information company. This study's methodology has its origin in Keynes's simple idea of precautionary liquidity demand: When a firm faces financial constraints, cash savings from earnings or cash inflows become important from the corporate finance perspective. Following this simple idea, Almeida et al. (2004) developed their theoretical model and found empirical evidence that the sensitivity of cash to cash flows varies systematically according to different types of financing frictions. To find more empirical evidence for this idea, we examined the cash flow sensitivity of the cash held by Korean retail firms. Results - Through several robustness tests, we empirically showed that financially constrained Korean retail firms display significant positive propensity to save cash from earnings before interest and taxes, while the estimated cash flow sensitivity of the cash held by unconstrained retail firms is not significant. Despite the relatively low earnings of retail firms, their sensitivity is three times greater than that of manufacturing enterprises. This implies that Korean retail firms have greater intentions of facilitating future investments rather than current investments. Conclusions - The characteristics of the cash policies of Korean retail firms differ from those of manufacturing firms. This contrast may be attributable to industry-oriented policy planning, regulations, and institutional differences. However, the industrial policymakers should observe signals of the long-term growth options of retail firms based on their high propensity to save from their cash inflows.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.1-7
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• 2020

In recent years, as LED display systems are actively spread, study on effective control methods for an LED driver for driving the systems has been in progress. The most representative among them is the uniform brightness control method for the LED driver channel. In this paper, we propose an LED driver IC for BLU with current compensation and system protection functions to minimize channel luminance deviation. It is designed for current accuracy within ±3% between channels and a channel current of 150 mA. In order to satisfy the design specifications, the channel amplifier offset was canceled out by a chopping operation using a channel-driving PWM signal. Also, a pre-charge function was implemented to minimize the fast operation speed and luminance deviation between channels. LED error (open, short), switch TR short detection, and operating temperature protection circuits were designed to protect the IC and BLU systems. The proposed IC was fabricated using a Magnachip 0.35-um CMOS process and verified using Cadence and Synopsys' Design Tool. The fabricated LED driver IC has current accuracy within ±1.5% between channels and 150-mA channel output characteristics. The error detection circuits were verified by a test board.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.183-183
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• 2014

Recently, multiferroic materials gain much attention due to their fascinating fundamental physical properties. These materials offer wide range of potential applications such as data storage, spintronic devices and sensors, where both electronic and magnetic polarizations can be coupled. Among single-phase multiferroic materials, $BiFeO_3$ is typical because of the room-temperature magnetoelectric coupling in view of long-range magnetic- and ferroelectric-ordering temperatures. However, $BiFeO_3$ is well known to have large leakage current and small spontaneous polarization due to the existence of oxygen vacancies and other defects. Furthermore the magnetic moment of pure $BiFeO_3$ is very weak owing to its antiferromagnetic nature. Recently, various attempts have been performed to improve the multiferroic properties of $BiFeO_3$ through the co-doping at the A and the B sites, by making use of the fact that the intrinsic polarization and magnetization are associated with the lone pair of $Bi^{3+}$ ions at the A sites and the partially-filled 3d orbitals of $Fe^{3+}$ ions at the B sites, respectively. In this study, $BiFeO_3$, $Bi_{0.9}Ho_{0.1}FeO_3$, $BiFe_{0.97}Ni_{0.03}O_3$ and $Bi_{0.9}Ho_{0.1}Fe_{0.97}Ni_{0.03}O_3$ bulk compounds were prepared by solid-state reaction and rapid sintering. High-purity $Bi_2O_3$, $Ho_2O_3$, $Fe_2O_3$ and $NiO_2$ powders with the stoichiometric proportions were mixed, and calcined at $500^{\circ}C$ for 24 h to produce the samples. The samples were immediately put into an oven, which was heated up to $800^{\circ}C$ and sintered in air for 1 h. The crystalline structure of samples was investigated at room temperature by using a Rigaku Miniflex powder diffractometer. The field-dependent and temperature-dependent magnetization measurements were performed with a vibrating-sample magnetometer and superconducting quantum-interference device.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.429-440
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• 1994

This study attempt to evaluate the recreation space(two patterns ; one is open space ; forest, water-front space and free open space, the other recreational fercilities) located in the natural area based on clarifying the relationship between the physical conditions of these spaces and human response(users' cognitive evaluation and users' activity pattern). On this standpoint it was proceeded to analyses of the information which was collected by interviews to users who were in this open space at the natural park of Osaka Prefecture. Through this study, the results were summarized as follows ; 1) Forest and waterfront space are considered to be a basic factor of the composition in natural recreation areas. There was difference on the recreational value depending on condition of forest composition. The hardwood-forest apparently high in its efficiency. 2) Free open space is a definite recreational space surely wide in its scope of active of recreational use. The site should be setted up considering the plants conditions around and geographical features according to the recreational activities, and the ground cover should be well controlled. 3) The recreational facilities in natural settings such as the sightseeing tower, the insect display hall, and the camp site appeared to produce low value as a recreational space. It was desirable that recreational activities be allowed within the scope. Consequently, we should carefully consider environmental capacity and landscape to designing these spaces 4) Traditional history and cultural properties are recognized as part of recreational resource as and also as essence of the compositions. So continuos care and proportion of history and cultural properties should be guaranteed.

• KIISE Transactions on Computing Practices
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• v.21 no.2
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• pp.101-108
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• 2015

This paper presents the implementation of a system that recommends empirical best routes based on classification of large trajectory data. As many location-based services are used, we expect the amount of location and trajectory data to become big data. Then, we believe we can extract the best empirical routes from the large trajectory repositories. Large trajectory data is clustered into similar route groups using Hadoop MapReduce framework. Clustered route groups are stored and managed by a DBMS, and thus it supports rapid response to the end-users' request. We aim to find the best routes based on collected real data, not the ideal shortest path on maps. We have implemented 1) an Android application that collects trajectories from users, 2) Apache Hadoop MapReduce program that can cluster large trajectory data, 3) a service application to query start-destination from a web server and to display the recommended routes on mobile phones. We validated our approach using real data we collected for five days and have compared the results with commercial navigation systems. Experimental results show that the empirical best route is better than routes recommended by commercial navigation systems.

• Resources Recycling
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• v.27 no.3
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• pp.16-29
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• 2018

In this study, metal and nonmetal contents and their economic values in ICT devices such as smart phones and laptop computers were evaluated. The electronic devices made by LG and Samsung were disassembled into 5 parts, which are printed circuit board assembly, battery, display, case and other electronic components. Metal and nonmetal contents in these parts were analyzed, and their economic values were calculated via multiplying the materials' contents by metal price obtained from KOMIS or nonmetal exchange price acquired from Korean recycling markets. Finally, the materials' contents and values according to each electronic parts and electronic devices were calculated. The results showed that the value of the smartphones and laptop computers of LG are 4,449.6 KRW (28,506 KRW/kg) and 6,830.2 KRW (7,053 KRW/kg), and those of Samsung are 1,849.3 KRW (13,499 KRW/kg) and 6,667.5 KRW (4,831 KRW/kg), respectively. It was also found that most of the value was concentrated in batteries and printed circuit board assemblies. In addition, Co, Au and Cu were found to be the most valuable resources in the devices.

• Journal of the Korean association of regional geographers
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• v.16 no.6
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• pp.706-723
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• 2010

The impervious surface was frequently employed as a proxy of the total environmental burden in the urban area. The impervious surface was extracted from a satellite image and the GIS (Geographical Information System) database for childhood asthma hospitalizations was generated for a total of 62,136 children using the National Health Insurance database of South Korea. Children living in an impervious environment do result in almost twice as many hospitalizations (26.58%) for asthma, as compared to the sub-urban pervious living (15.82%). Furthermore, the risk zones with persistently high hospitalizations for three years were specifically identified over the impervious sub-district alone. The impervious zone showed a small inter-year variation of hospitalizations (r: 0.937) while the sub-urban pervious fringe was found to display a yearly variation(r: 0.371). The strong temporal autocorrelation means that the impervious areas have frequent long-lived hospitalizations for asthma, thus children living in impervious areas were likely to have had more chronic asthma attacks than those living in pervious areas. These experimental results indicate that an impervious surface as thematic parameter of analysis is a crucial explanatory variable for asthma hospitalizations and its longer persistence among children.