• The Journal of the Korean bone and joint tumor society
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• v.13 no.2
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• pp.96-104
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• 2007

Purpose: The authors investigated whether 35 flexible nail-rotating hinge composite reconstructions around knee joint minimize junctional osteolysis of host bone. Material and Method: The reconstructive technique was as follows: 1) en bloc tumor resection, 2) filling of the host bone marrow cavity with multiple Ender nails, 3) assembling the Ender nails and an Endo-Link type total knee component with wire and bone cement. Result: Mean follow-up was 53 months (ranged 30~79). At final follow-up, 29 patients retained a mobile joint. Resection of more than 40% of bone showed a positive relationship with junctional hypertrophy (p=0.028). Eight patients showed nail breakage and eight prostheses were removed due to early or late infection. The cumulative prosthetic survival rate was 33% at 6 year. Average functional score according to the MSTS criteria was 26.8. Conclusion: Mid-term evaluations showed that results were fair. The revision process was straightforward. Junctional hypertrophy observed appears to give some clues as to how to minimize osteolysis at the prosthesis-host junction after modular prosthesis fixation.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.263-268
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• 2010

Purpose: Eye movements and fixation ability are an important procedure to obtain external information and essential means of clear vision. The purpose of this study was to determine the reading performance such as reading time and number of fixations when random text was viewed at varying distances. Methods: Twenty two presbyopes were participated. All subjects were screened for their suitability to participate in the study by clinical examination, and none of the participants had previously worn contact lenses and no previous experience of wearing any types of presbyopic vision correction except single vision. The reading time and number of fixations were recorded using eye tracker while each subjects was waring four vision corrections which included single vision for distance (SV), bifocal spectacle lenses (BIF), progressive addition lenses (PAL), and monovision (MV). The reading material was presented at distance and near distance. Results: Reading time and number of fixations for near stimulus were significantly different among vision correction used in this study (p<0.001). In particular, wearing SV required longer reading time and produced longer fixation duration for near text. However, reading distance text was similarity performed across vision corrections tested and there was no statistical difference found for either reading time and number of fixations. Conclusions: Wearing presbyopic vision correction is advantageous for reading task of near stimuli, but not having near correction such as wearing SV could result in longer reading time and higher number of fixation due to lacks of accommodative ability for near task. For the future studies, it would be interesting to examine the performance of reading both at adapted and unadapted stages as examining only unadapted wearers was limitation of this study.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.3
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• pp.318-329
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• 2010

The purpose of this study was to develop the $PM_{2.5}$ source profiles for diesel and gasoline-powered vehicles, which contained mass abundances in terms of mass fraction of $PM_{2.5}$ of chemical species. Seven diesel-powered vehicles and nine gasoline-powered vehicles were sampled from a chassis dynamometer exhaust dilution system. The species measured were water-soluble ions, elements, elemental carbon (EC), and organic carbon (OC). From this study, the large abundances of EC (54.5%), OC (26.0%), ${SO_4}^{2-}$ (1.5%), ${NO_3}^-$ (0.8%), and S (0.6%) were observed from the diesel-powered vehicle exhaust showing that carbons were dominant species. The gasoline-powered vehicle exhaust emitted large abundances of OC (38.3%), EC (4.2%), ${SO_4}^{2-}$ (3.6%), ${NH_4}^+$ (3.5%), and ${NO_3}^-$ (3.0%). The abundances of ${SO_4}^{2-}$, ${NH_4}^+$, and ${NO_3}^-$ from gasoline vehicle were greater than those of diesel vehicle. The emissions of P, S, Ca, Fe, and Zn among trace elements for the gasoline vehicle were greater than 1% of the $PM_{2.5}$ mass unlike those for the diesel vehicle. Particularly, the fraction of Zn was five times higher from the gasoline vehicle than that from the diesel vehicle. The source profiles developed in this work were intensively examined by applying chemical mass balance model.

• Analytical Science and Technology
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• v.29 no.5
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• pp.234-241
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• 2016

The approach presented in this article refers to the bioanalytical method validation for the detection and quantitative determination of arsenic species including arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) in dog plasma by high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP/MS). The arsenic species were separated using an agilent As speciation column by a mobile phase of 2 mM sodium phosphate monobasic, 0.2 mM ethylenediaminetetraacetic acid disodium salt dehydrate, 10 mM sodium acetate, 3 mM sodium nitrate and 1 % ethyl alcohol at pH 11 (adjusted with 1M NaOH). The method validation experiment was obtained selectivity, linearity, accuracy, precision, matrix effect, recovery, system suitability, dilution integrity and various stabilities. All calibration curves showed good linearity (R²>0.999) within test ranges. The lower limit of quantitation (LLOQ) was 5 ng/mL for As(III), As(V) and DMA, and 20 ng/mL for MMA. The system suitability and dilution values were within 6.5 % and 7.7 %. Subsequently, the developed and validated HPLC-ICP/MS method was also successfully applied to determine the arsenic speciation in dog plasma samples, and the recoveries for the spiked samples were in the range of 91.5–102.2 %. Therefore, this method could be applied to the evaluation of arsenic exposure, health effect assessment and other bio-monitoring studies in biological samples.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.209-217
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• 2022

The purpose of this study was to confirm the dissolution of arsenic from the stabilized soil around abandoned coal mines by cultivation activities. Experimental soils were collected from the agricultural field around Okdong and Buguk coal mines, and the concentration of arsenic in the soil and the geochemical mobility were confirmed. The average arsenic concentration was 20 mg/kg. The soil with relatively high geochemical mobility of arsenic in the soil was used in the batch and column experiment. The limestone was mixed with soil for soil stabilization, and the mixing ratio was 3% of limestone, based on the soil weight. The phosphoric acid fertilizer (NH₄H₂PO₄) was added to the soil to simulate a cultivation condition according to the Rural Development Administration's rules. Comparative soil without mixing limestone was prepared and used as a control group. The arsenic extraction from soil was increased following the fertilizer mixing amount and it shows a positive relationship. The concentration of phosphate in the supernatant was relatively low under the condition of mixing limestone, which is determined to be result of binding precipitation of phosphate ions and calcium ions dissolved in limestone. Columns were set to mix phosphoric acid fertilizers and limestone corresponding to cultivation and stabilization conditions, and then the column test was conducted. The variations of arsenic extraction from the soil indicated that the stabilization was effectible until 10 P.V.; however, the stabilization effect of limestone decreased with time. Moreover, the geochemical mobility of arsenic has transformed by increasing the mobile fractions in soil compared to initial soil. Therefore, based on the arsenic extraction results, the cultivation activities using phosphoric fertilizer could induce a decrease in the stabilization effect.

• Journal of Global Scholars of Marketing Science
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• v.19 no.4
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• pp.11-23
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• 2009

HSDPA (High-Speed Downlink Packet Access) is a 3.5-generation asynchronous mobile communications service based on the third generation of W-CDMA. In Korea, it is mainly provided in through videophone service. Because of the diffusion of more powerful and diversified services, along with steep advances in mobile communications technology, consumers demand a wide range of choices. However, because of the variety of technologies, which tend to overflow the market regardless of consumer preferences, consumers feel increasingly confused. Therefore, we should not adopt strategies that focus only on developing new technology on the assumption that new technologies are next-generation projects. Instead, we should understand the process by which consumers accept new forms of technology and devise schemes to lower market entry barriers through strategies that enable developers to understand and provide what consumers really want. In the Technology Acceptance Model (TAM), perceived usefulness and perceived ease of use are suggested as the most important factors affecting the attitudes of people adopting new technologies (Davis, 1989; Taylor and Todd, 1995; Venkatesh, 2000; Lee et al., 2004). Perceived usefulness is the degree to which a person believes that a particular technology will enhance his or her job performance. Perceived ease of use is the degree of subjective belief that using a particular technology will require little physical and mental effort (Davis, 1989; Morris and Dillon, 1997; Venkatesh, 2000). Perceived pleasure and perceived usefulness have been shown to clearly affect attitudes toward accepting technology (Davis et al., 1992). For example, pleasure in online shopping has been shown to positively impact consumers' attitudes toward online sellers (Eighmey and McCord, 1998; Mathwick, 2002; Jarvenpaa and Todd, 1997). The perceived risk of customers is a subjective risk, which is distinguished from an objective probabilistic risk. Perceived risk includes a psychological risk that consumers perceive when they choose brands, stores, and methods of purchase to obtain a particular item. The ability of an enterprise to revolutionize products depends on the effective acquisition of knowledge about new products (Bierly and Chakrabarti, 1996; Rothwell and Dodgson, 1991). Knowledge acquisition is the ability of a company to perceive the value of novelty and technology of the outside (Cohen and Levinthal, 1990), to evaluate the outside technology that has newly appeared (Arora and Gambaradella, 1994), and to predict the future evolution of technology accurately (Cohen and Levinthal, 1990). Consumer innovativeness is the degree to which an individual adopts innovation earlier than others in the social system (Lee, Ahn, and Ha, 2001; Gatignon and Robertson, 1985). That is, it shows how fast and how easily consumers adopt new ideas. Innovativeness is regarded as important because it has a significant effect on whether consumers adopt new products and on how fast they accept new products (Midgley and Dowling, 1978; Foxall, 1988; Hirschman, 1980). We conducted cross-national comparative research using the TAM model, which empirically verified the relationship between the factors that affect attitudes - perceived usefulness, ease of use, perceived pleasure, perceived risk, innovativeness, and perceived level of knowledge management - and attitudes toward HSDPA service. We also verified the relationship between attitudes and usage intention for the purpose of developing more effective methods of management for HSDPA service providers. For this research, 346 questionnaires were distributed among 350 students in the Republic of Korea. Because 26 of the returned questionnaires were inconsistent or had missing data, 320 questionnaires were used in the hypothesis tests. In UK, 192 of the total 200 questionnaires were retrieved, and two incomplete ones were discarded, bringing the total to 190 questionnaires used for statistical analysis. The results of the overall model analysis are as follows: Republic of Korea x2=333.27(p=0.0), NFI=0.88, NNFI=0.88, CFI=0.91, IFI=0.91, RMR=0.054, GFI=0.90, AGFI=0.84, UK x2=176.57(p=0.0), NFI=0.88, NNFI=0.90, CFI=0.93, IFI=0.93, RMR=0.062, GFI=0.90, AGFI=0.84. From the results of the hypothesis tests of Korean consumers about the relationship between factors that affect intention to use HSDPA services and attitudes, we can conclude that perceived usefulness, ease of use, pleasure, a high level of knowledge management, and innovativeness promote positive attitudes toward HSDPA mobile phones. However, ease of use and perceived pleasure did not have a direct effect on intention to use HSDPA service. This may have resulted from the fact that the use of video phones is not necessary for everyday life yet. Moreover, it has been shown that attitudes toward HSDPA video phones are directly correlated with usage intention, which means that perceived usefulness, ease of use, pleasure, a high level of knowledge management, and innovativeness. These relationships form the basis of the intention to buy, contributing to a situation in which consumers decide to choose carefully. A summary of the results of the hypothesis tests of European consumers revealed that perceived usefulness, pleasure, risk, and the level of knowledge management are factors that affect the formation of attitudes, while ease of use and innovativeness do not have an effect on attitudes. In particular, with regard to the effect value, perceived usefulness has the largest effect on attitudes, followed by pleasure and knowledge management. On the contrary, perceived risk has a smaller effect on attitudes. In the Asian model, ease of use and perceived pleasure were found not to have a direct effect on intention to use. However, because attitudes generally affect the intention to use, perceived usefulness, pleasure, risk, and knowledge management may be considered key factors in attitude development from which usage intention arises. In conclusion, perceived usefulness, pleasure, and the level of knowledge management have an effect on attitude formation in both Asian and European consumers, and such attitudes shape these consumers' intention to use. Furthermore, the hypotheses that ease of use and perceived pleasure affect usage intention are rejected. However, ease of use, perceived risk, and innovativeness showed different results. Perceived risk had no effect on attitude formation among Asians, while ease of use and innovativeness had no effect on attitudes among Europeans.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.491-501
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• 2002

A cross-examination between KT&G Central Research Institute and Guangzhou Institute for Drug Control was carried out in order to select optimum conditions for extraction, separation and determination of ginsenosides in red ginseng and to propose a better method for the quantitative analysis of ginsenosides. The optimum extraction conditions of ginsenosides from red ginseng were as follows: the extraction solvent, $70\%$ methanol; the extraction temperature, $100^{\circ}C;$ the extraction time, 1 hour for once; and the repetition of extraction, twice. The optimum separation conditions of ginsenosides on the SepPak $C_{18}$ cartridge were as follows: the loaded amount, 0.4 g of methanol extract; the washing solvents, distilled water of 25 ml at first and then $30\%$ methanol of 25 ml; the elution solvent, $90\%$ methanol of 5 ml. The optimum HPLC conditions for the determination of ginsenosides were as follows: column, Lichrosorb $NH_2(25{\times}0.4cm,$ 5${\mu}m$, Merck Co.); mobile phase, a mixture of acetonitrile/water/isopropanol (80/5/15) and acetonitrile/water/isopropanol (80/20/15) with gradient system; and the detector, ELSD. On the basis of the optimum conditions a method for the quantitative analysis of ginsenosides were proposed and another cross-examination was carried out for the validation of the selected analytical method conditions. The coefficient of variances (CVs) on the contents of ginsenoside-$Rg_{1}$, -Re and $-Rb_1$ were lower than $3\%$ and the recovery rates of ginsenosides were $89.4\~95.7\%,$ which suggests that the above extraction and separation conditions may be reproducible and reasonable. For the selected HPLC/ELSD conditions, the CVs on the detector responses of ginsenoside-Rg, -Re and $-Rb_1$) were also lower than $3\%$, the regression coefficients for the calibration curves of ginsenosides were higher than 0.99 and two adjacent ginsenoside peaks were well separated, which suggests that the above HPLC/ELSD conditions may be good enough for the determination of ginsenosides.

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.25-39
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• 1994

The Deogbong napseok clay deposit which is composed mainly of dickite and pyrophyllite has been formed by hydrothermal alteration of the Late Cretaceous volcanic rocks consisting of andesitic tuff and andesite. The mineralogy of the napseok ores and the hydrothermal alteration processes have been studied in order to know the nature of the interaction between minerals and fluids for the formation of the deposit. Chemical distribution shows that alkali elements and silica were mobile but alumina was relatively immobile during the hydrothermal processes. It is evident that enrichment of alumina and leaching of silica from the host rock led to the formation of the napseok ore, whereas the enrichment of silica in the outer zone of the deposit gave rise to the silica zone. A large amount of microcrystalline quartz closely associated with dickite and pyrophyllite suggests the increasing activity of silica. Thus Si which was released away from the argillic zone by the increasing activity of silica. Thus Si which was released away from the argillic zone by the increasing activity of silica solubility moved out precipitating in the margin of the deposit to form the silica zone. Variation in dickite crystallinity implies the local change in the stability of the system. Thermodynamic calculation shows that the invariant point of pyrophyllite-dickite (kaolinite)-diaspore-quartz assemblages at 500 bars in the system $Al_{2}O_{3}-SiO_{2}-H_{2}O$ is about 300 $^{\circ}C$. Based on the mineral assemblages and the experimental data reported, it is estimated that the main episode of hydrothermal alteration occurred at least above 270 to 300 $^{\circ}C$ and $X_{CO_2}$ <0.025. Mineral occurrence and chemical variation indicate that the activity of Al is high in the upper part of the deposit, whereas the activity of Si is high in the lower part and the margin of the deposit. The nonequilibrium phase relations observed in the Deogbong deposit might be due to local change in intensive thermodynamic variables and fluid transport properties that resulted in the formation of nonequilibrium phases b of several stages.

• Journal of Nutrition and Health
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• v.48 no.2
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• pp.180-191
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• 2015

Purpose: There is a lack of data on the energy cost of children's everyday activities, adult values are often used as surrogates. In addition, the influence of body weight on the energy cost of activity when expressed as metabolic equivalents (METs) has not been vigorously explored. Methods: In this study 20 elementary school students 9~12 years of age completed 18 various physical activities while energy expenditure was measured continuously using a portable telemetry gas exchange system ($K_4b^2$, Cosmed, Rome, Italy). Results: The average age was 10.4 years and the average height and weight was 145.1 cm and 43.6 kg, respectively. Oxygen consumption ($VO_2$), energy expenditure and METs at the time of resting of the subjects were 5.41 mL/kg/min, 1.44 kcal/kg/h, and 1.5 METs, respectively. METs values by 18 physical activities were as follows: Homework and reading books (1.6 METs), playing game with a mobile phone or video while sitting (1.6 METs), watching TV while sitting on a comfortable chair (1.7 METs), playing video game or mobile phone game while standing (1.9 METs), sweeping a room with a broom (2.7 METs) and playing a board game (2.8 METs) belong to light intensity physical activities. By contrary, speedy walking and running were 6.6 and 6.7 METs, respectively, which belong to high intensity physical activities over 6.0 METs. When the effect of body weight on physical activity energy expenditure was determined, $R^2$ values increased with 0.116 (playing a game at sitting), 0.176 (climbing up and down stairs), 0.246 (slow walking), and 0.455 (running), which showed that higher activity intensity increased explanation power of body weight on METs value. Conclusion: This study is important for direct evaluation of energy expenditure by physical activities of children, and it could be used directly for revising and complementing the existing activity classification table to fit for children.

• Journal of Intelligence and Information Systems
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• v.17 no.1
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• pp.53-69
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• 2011

Vision and voice-based technologies are commonly utilized for human-robot interaction. But it is widely recognized that the performance of vision and voice-based interaction systems is deteriorated by a large margin in the real-world situations due to environmental and user variances. Human users need to be very cooperative to get reasonable performance, which significantly limits the usability of the vision and voice-based human-robot interaction technologies. As a result, touch screens are still the major medium of human-robot interaction for the real-world applications. To empower the usability of robots for various services, alternative interaction technologies should be developed to complement the problems of vision and voice-based technologies. In this paper, we propose the use of accelerometer-based gesture interface as one of the alternative technologies, because accelerometers are effective in detecting the movements of human body, while their performance is not limited by environmental contexts such as lighting conditions or camera's field-of-view. Moreover, accelerometers are widely available nowadays in many mobile devices. We tackle the problem of classifying acceleration signal patterns of 26 English alphabets, which is one of the essential repertoires for the realization of education services based on robots. Recognizing 26 English handwriting patterns based on accelerometers is a very difficult task to take over because of its large scale of pattern classes and the complexity of each pattern. The most difficult problem that has been undertaken which is similar to our problem was recognizing acceleration signal patterns of 10 handwritten digits. Most previous studies dealt with pattern sets of 8~10 simple and easily distinguishable gestures that are useful for controlling home appliances, computer applications, robots etc. Good features are essential for the success of pattern recognition. To promote the discriminative power upon complex English alphabet patterns, we extracted 'motion trajectories' out of input acceleration signal and used them as the main feature. Investigative experiments showed that classifiers based on trajectory performed 3%~5% better than those with raw features e.g. acceleration signal itself or statistical figures. To minimize the distortion of trajectories, we applied a simple but effective set of smoothing filters and band-pass filters. It is well known that acceleration patterns for the same gesture is very different among different performers. To tackle the problem, online incremental learning is applied for our system to make it adaptive to the users' distinctive motion properties. Our system is based on instance-based learning (IBL) where each training sample is memorized as a reference pattern. Brute-force incremental learning in IBL continuously accumulates reference patterns, which is a problem because it not only slows down the classification but also downgrades the recall performance. Regarding the latter phenomenon, we observed a tendency that as the number of reference patterns grows, some reference patterns contribute more to the false positive classification. Thus, we devised an algorithm for optimizing the reference pattern set based on the positive and negative contribution of each reference pattern. The algorithm is performed periodically to remove reference patterns that have a very low positive contribution or a high negative contribution. Experiments were performed on 6500 gesture patterns collected from 50 adults of 30~50 years old. Each alphabet was performed 5 times per participant using $Nintendo{(R)}$ $Wii^{TM}$ remote. Acceleration signal was sampled in 100hz on 3 axes. Mean recall rate for all the alphabets was 95.48%. Some alphabets recorded very low recall rate and exhibited very high pairwise confusion rate. Major confusion pairs are D(88%) and P(74%), I(81%) and U(75%), N(88%) and W(100%). Though W was recalled perfectly, it contributed much to the false positive classification of N. By comparison with major previous results from VTT (96% for 8 control gestures), CMU (97% for 10 control gestures) and Samsung Electronics(97% for 10 digits and a control gesture), we could find that the performance of our system is superior regarding the number of pattern classes and the complexity of patterns. Using our gesture interaction system, we conducted 2 case studies of robot-based edutainment services. The services were implemented on various robot platforms and mobile devices including $iPhone^{TM}$. The participating children exhibited improved concentration and active reaction on the service with our gesture interface. To prove the effectiveness of our gesture interface, a test was taken by the children after experiencing an English teaching service. The test result showed that those who played with the gesture interface-based robot content marked 10% better score than those with conventional teaching. We conclude that the accelerometer-based gesture interface is a promising technology for flourishing real-world robot-based services and content by complementing the limits of today's conventional interfaces e.g. touch screen, vision and voice.