• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.26-28
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• 2000

A novel oxidant generation and ion precipitation cell with slits on parallel plate electrodes system has been proposed and an effect of the number and size of slits on ion precipitation and oxidant generation characteristics. As a result, with the electrodes with 48 slits($S=200{\times}60[mm^2]$. d = 1.5, 5.0 [mm]), it is found that the oxidant contained waters of 17.0 [ppmm] and 23.5 [ppmm] in acid water were obtained with 0.1 [wt%] NaCl dissolved tap water fed. And oxidant contained waters of 0.5 [ppmm] and 1.5 [ppmm] in alkali water were obtained with 0.1 [wt%] NaCl dissolved tap water fed. And the oxidant contained waters of 7.0 [ppmm] and 11.5 [ppmm] in mixed water were obtained with tap water and 0.1 [wt%] NaCl dissolved tap water fed. Consequently, very high ion precipitation and dense oxidant generation characteristics can be realized by having slits on the electrodes of conventional cells as these slits increase the electric fields and decrease the space charge limiting actions in interelectrode space.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.4
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• pp.328-336
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• 2000

In order to compare the effect of water quality on two service systems, tank and direct connection service, we selected randomly 30 rooftop tanks installed in the buildings with five or fewer floors, and collected water samples from each tank as well as tap water by direct service. At the same time each tank was investigated on their cleanliness and sanitary control. 30 water samples from direct service met Korean Drinking water quality standard. But 5 tank water samples(17%) were not able to meet Coliform or Total Colony Counts standard and free chlorine of 12 tank water samples(40%) were less than 0.2mg/L. Also Fe, Turbidity, TOC, Total Algae in tank water were higher than tap water on direct service. We concluded that thorough health control of water tank is necessary and conversion into direct connection service results in improving tap water quality importantly.

• IE interfaces
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• v.22 no.4
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• pp.347-358
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• 2009

Panning tasks caused by both a small screen and the lower resolution of handheld devices are known to decrease the usability of a mobile internet service. To solve this problem, we proposed FTND, an improved version of Tap-N-Drag widely used in various mobile web browsers. 30 participants performed the panning tasks with FTND embedded in combinations of 2 panning directions of Push Background user interface and Push Viewpoint user interface and 5 panning ratios of 100% (a panning ratio of Tap- N-Drag), 300%, 500%, 700%, and 900%. The usability of FTND was assessed by an objective performance and a subjective preference. The objective performance was measured by a task completion time, the number of clicks, and the number of pixels. The subjective preference was measured by satisfaction, accuracy and ease of use. Push Viewpoint user interface at the panning ratios of 300%, 500%, and 700% proved to be the most efficient way for panning tasks with small handheld devices when performing the task by using the right hand thumb.

• Journal of the Korean earth science society
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• v.41 no.4
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• pp.405-414
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• 2020

In this study, we analyzed the development of high school students' argumentation through their writings on socio-scientific Issues (SSI) related to the Climate Change Unit in the Earth Science I curriculum. Pre- and post-writing assignments on the two main causes of global warming were analyzed and compared. In addition, an in-depth interview of the focus group was conducted with 7 students who showed a distinct change in the level of argumentation. According to the results, 16 of 52 students remained at the same argumentation level in pre- and post-writing assignments, and students remaining at Level 2 among five levels had difficulty in understanding the Toulmin's argument pattern (TAP) structure. Using the TAP structure, 29 of 52 students demonstrated increased argumentation levels in the post-writing assignments. The conclusions include that writing lessons on SSI using the TAP in Earth science classes can improve the level of high school students' argumentative writing, and that the level of students' argumentation can develop with the elaboration of their level of falsification. Also, it is suggested that the science curriculum should increase students' science writing competencies by specifying science writing as one of the goals.

• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.69-75
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• 1988

The drinking water in the apartment is stored in reservior tank and thereafter supplied each household. In case the drinking water is stored too long or insanitary, tap water might change in quality. This study was carried out to evaluate the physico-chemical and microbiological conditions of 36 samples of tap water of apartments compared to 18 samples of tap water of independence houses in Taegu City from May to October, 1987. Main findings are summarized as follows : PH values were within normal range in all samples. Samples less than 0.2ppm in residual chlorine accounted for 16.7% in the appartment and 5.6% in the independence house. Nitrite nitrogen was detected 2.8% of apartment samples only. Among the total of 54 samples, 11.1% of the apartment and independence samples were over the normal value in standard plate count. Samples more than 1.8 of most probable number(MPN) accounted for 27.8% in the apartment and 33.3% in the independence house. In result of test for residual chlorine, nitrite nitrogen, standard plate count, and MPN, the proportion of the samples revealed inappropriated in respect of drinking water standards. In case of all sorts of tests was 2.7% in apartment and nothing in independence houses, in case of 3 sorts of tests was 2.7% in apartment and 5.6% in independence houses, in case of 2 sorts of tests was 8.3% in apartment and 5.6% in independence houses, and in case of only 1 test was 25.0% in apartment and 22.2% in independence houses. Correlation between residual chlorine and standard plate count, and between standard plate count and MPN were observed. It was found that the more years since construction of apartment were, the worse tap water was in quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.726-732
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• 2019

In this study, we proposed an asymmetric differential inductor to improve the linearity of differential power amplifiers. Considering the phase error between differential signals of the differential amplifier, the location of the center tap of the differential inductor was modified to minimize the error. As a result, the center tap was positioned asymmetrically inside the differential inductor. With the asymmetric differential inductor, the AM-to-AM and AM-to-PM distortions of the amplifier were suppressed. To confirm the feasibility of the inductor, we designed a 2.4 GHz differential CMOS PA for IEEE 802.11n WLAN applications with a 64-quadrature amplitude modulation (QAM), 9.6 dB peak-to-average power ratio (PAPR), and a bandwidth of 20 MHz. The designed power amplifier was fabricated using the 180-nm RF CMOS process. The measured maximum linear output power was 17 dBm, whereas EVM was 5%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.565-568
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• 2008

In this paper, we present bit error rate(BER) performance of an adaptive decision feedback equalizer(DFE) with experimental data. The experiment was performed at the shore of Geoje in November 2007. The BER performance of the adaptive DFE whose tap weight is updated by RLS is described with change of feedforward tap number, feedback tap number, traning seqence length and delay, which shows that the uncoded average BER is $4{\times}10^{-2}\;and\;1.5{\times}10^{-2}$ with transmission range 9.7km and 4km, respectively.

• Environmental Analysis Health and Toxicology
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• v.18 no.3
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• pp.199-208
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• 2003

A new technique was proposed for the determination of alkylphenols, chlorophenols and bisphenol A in tap water samples. The sample preparation consists of a solid phase extraction (SPE) of alkylphenols, chlorophenols and bisphenol A from a water sample with XAD-4 and subsequent conversion to isobutyloxycarbonyl (isoBOC) derivatives or tert-butyldimethylsilyl (TBDMS) derivatives for sensitive analysis with the CC/MS SIM mode. The recoveries were 86.6 ∼ 105.2％ (isoBOC derivatization) and 97.6∼484.5％ (TBDMS derivatization), respectively. The limit of quantitation of alkylphenols, chlorophenols and bisphenol h for SIM were 0.001∼0.050 $\mu\textrm{g}$/1 (isoBOC derivatization) and 0.003∼0.050 $\mu\textrm{g}$/1 (TBDMS derivatization). The SIM responses were linear with the correlation coefficient varying 0.9755∼0.9981 (isoBOC derivatization), and 0.9908∼0.9996 (TBDMS derivatization). When these methods were applied to tap water samples, the range of concentrations were 22.8∼31.3 ng/1 in 2,4-dichlorophenol, 28.6∼70.3 ng/1 in pentachlorophenol, 15.2∼17.4 ng/1 in t-butylphenol, 10.8∼13.2 ng/1 in t-octylphenol and 17.6∼36.3 ng/l in bisphenol A, respectively.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.1
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• pp.1-10
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• 2013

In JPEG2000, the Cohen-Daubechies-Feauveau (CDF) 9/7-tap wavelet filter is implemented using the conventional lifting scheme. On the other hand, this wavelet filter has two problems: the filter coefficients remain complex, and the conventional lifting scheme does not consider the image edges in the coding process. This paper proposes an effective lifting scheme to solve these problems. For this purpose, optimal 9/7-tap wavelet filters were designed in two steps. In the first step, the appropriate filter coefficients were selected. In the second step, a median operator was employed to consider the image edges. The experimental results with the median lifting scheme and the combination of filter optimization with the median lifting show that the proposed methods outperform the well-known CDF 9/7-tap wavelet filter of JPEG2000 on the edge-dominant images.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.998-1004
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• 1987

This paper describes the design theory of a weakly-coupled Tap-off with high density of coupling intervals for CATV ynd/or MyTV systyms, by yhich the degree of freedom in design and density of coupling intervals are significantly increased compared with the intrinsic one. It is also described how a 2-way power divider(Tap-off) is constructed in the generalized type. Furtuermore, the practical measurements of the frequency characteristics for a fabricated circuit show very good agreements with theoretical results, and, hence, the validity of the proposed design and analyses methods are confirmed.