• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.9
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• pp.597-604
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• 2016

A parallel algorithm of bi-conjugate gradient method was developed based on CUDA for parallel computation of the incompressible Navier-Stokes equations. The governing equations were discretized using splitting P2P1 finite element method. Asymmetric stenotic flow problem was solved to validate the proposed algorithm, and then the parallel performance of the GPU was examined by measuring the elapsed times. Further, the GPU performance for sparse matrix-vector multiplication was also investigated with a matrix of fluid-structure interaction problem. A kernel was generated to simultaneously compute the inner product of each row of sparse matrix and a vector. In addition, the kernel was optimized to improve the performance by using both parallel reduction and memory coalescing. In the kernel construction, the effect of warp on the parallel performance of the present CUDA was also examined. The present GPU computation was more than 7 times faster than the single CPU by double precision.

• Journal of Nutrition and Health
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• v.35 no.9
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• pp.943-951
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• 2002

This study was designed to investigate the effects of iron supplementation and nutrition education on the iron status and anemia of high school girls. The subjects resided in Ulsan city in Korea and were already diagnosed as having anemia or iron deficiency. Over a period of three months, one iron tablet (80 mg Fe as ferrous sulfate/day) was administered to the iron deficient subjects and two tablets (160 mg Fe as ferrous sulfate/day) were administered to the anemia subjects. The average height and weight of anemia subjects were 161.24 $\pm$ 4.50 cm and 50.87 $\pm$ 5.86 kg, respectively. The average BMI (kg/$m^2$ )was 19.58 $\pm$ 2.03 and the PIBW(percent ideal body weight) were 92.52 $\pm$ 9.84%. Except for vitamin A and vitamin C intakes, the intake levels of all other nutrients were below the RDA. Total calorie intakes of anemia subjects were 73.5% of RDA. The iron intakes of subjects from food were 69. 1% of RDA and the Ca intakes were 59.1% of RDA. The basal hemoglobin(Hb) concentration of anemia subjects averaged 10.77 $\pm$ 1.33 g/dl, and this increased significantly (p < 0.001) to 12.12 $\pm$ 1.08 g/dl, after iron supplementation. The basal ferritin, and transferrin saturations ｛TS (%)｝of anemia subjects were 12.51 $\pm$ 15.19 ng/$m\ell$ and 8.43 $\pm$ 7.56%, respectively, and these significantly increased to 20.59 $\pm$ 22.39 ng/$m\ell$ and 15.56 $\pm$ 12.87%, respectively. The level of total iron binding protein (TIBC) significantly decreased from the initial 486.80 $\pm$ 70.16 $\mu\textrm{g}$/dl to 417.86 $\pm$ 67.73 $\mu\textrm{g}$/dl (p < 0.001) after iron supplementation. For the iron deficiency subjects, the ferritin, iron and TS(%) levels were increased significantly (p < 0.001) and the TIBC levels were significantly (p <0.001) decreased after iron supplementation. Anemia symptoms such as 'Feeling blue (p<0.05)', 'Decreased ability to concentrate (p<0.001)' and 'Poor memory (p<0.05)' improved significantly after iron supplementation in the anemia subjects. The number of tablets administered was positively correlated with changes in serum hemoglobin (t=0.194, p< 0.01), serum ferritin (t=0.181, p<0.01), TS(%) (t=0.141, p<0.05), and hematocrit (t=0.254, p<0.01), and was negatively correlated with changes in TIBC (t=-0.143. p<0.05) and red cell distribution width (RDW, t=-0.140, p<0.05). In conclusion, daily iron supplementation was effective in improving the iron status and reducing symptoms of anemia in high school girls. (Korean J Nutrition 35 (9) : 943~951,2002)

• Journal of Nutrition and Health
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• v.37 no.3
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• pp.176-181
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• 2004

This study was designed to investigate the effects of buthanol (BuOH) fraction of pine (Pinus densiflora Sieb et Zucc) needle on cholesterol and lipofuscin (LF) accumulations, acetylcholine (ACh) and its related enzyme activities such as choline acetyltransferase (CAhT) and acetylcholinesterase (AChE), and monoamone oxidase-B (MAO-B) activity, which destroyed the catecholamine-related neurotransmitters in brain membranes of Sprague-Dawley (SD) rats. Male SD rats were fed basic diets (control group) or experimental diets (BuOH-25, BuOH-50 and BuOH-100) for 45 days. Cholesterol accumulations in mitochondria and microsomes were significantly inhibited (about 14 - 17％ and 23 - 34％, respectvely) in BuOH-50 and BuOH-100 groups, whereas LF levels were significantly inhibited (about 10 - 14％) in BuOH-50 and BuOH-100 groups compared with control group. ACh levels and ChAT activities were significantly increased (about 11 - 17％ and 11 - 23％, respectively) in membranes of BuOH-50 and BuOH-100 groups compared with control group. AChE activities were significantly increased (about 14 - 17％) in membranes of BuOH-50 and BuOH-100 groups. There was no significant difference in MAO-B activities between control and experimental diet groups. The results suggest that butanol fraction of pine needle may play an effective role in an antiaging effect and improving a learning and memory impairments.

• The Korea Journal of Herbology
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• v.31 no.1
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• pp.7-15
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• 2016

Objectives : Polygalae Radix (POL) has an ameliorating effect on learning and memory impairment caused by cerebral hypoperfusion. In regard to POL's action mechanism, this study was carried out to investigate the effects of POL on oxidative damage and neuronal apoptosis induced by cerebral hypoperfusion in rats.Methods : The cerebral hypoperfusion was induced by permanent bilateral common carotid artery occlusion (pBCAO) in Sprague-Dawley rats. POL was administered orally once a day (130 mg/kg of water-extract) for 28 days starting at 4 weeks after the pBCAO. Superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels in the brain tissue were measured using ELISA method. Expressions of 4-hydroxynonenal (4HNE) and 8-hydroxy-2'- deoxyguanosine (8-OHdG) were observed using immunohistochemistry. In addition, neuronal apoptosis was evaluated with Cresyl violet staining, TUNEL labeling, and immunohistochemistry against Bax and caspase-3.Results : POL treatment significantly increased SOD activities and significantly reduced MDA levels in the cerebral cortex. The up-regulations of 4HNE and 8-OHdG expression caused by pBCAO in the CA1 of hippocampus were significantly attenuated by POL treatment. POL treatment also restored the reduction of CA1 thickness and CA1 neurons caused by pBCAO and significantly attenuated the apoptotic markers including TUNEL-positive cells, Bax, and caspase-3 expression in the CA1 of hippocampus.Conclusions : The results show that POL attenuated the oxidative damage in brain tissue and neuronal apoptosis in the hippocampus caused by the cerebral hypoperfusion. It suggests that POL can be a beneficial medicinal herb to treat the brain diseases related to cerebral hypoperfusion.

• Journal of The Korean Association For Science Education
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• v.34 no.7
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• pp.635-645
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• 2014

The purpose of this study is to identify elementary school teachers' perceptions, practices, and background factors related to introducing students' everyday experience in science teaching process. The participants of this study were four elementary school teachers who have different features such as major, teaching period, gender, growth area, and age. The data was collected through semi-constructed and in-depth interviews. The results of the research are as follows: Teachers mostly used students' everyday experience during the introduction phase of science lessons for the purpose of motivation. They hold a positive view of using students' everyday experience during science lessons and thought that science teaching needs to actively use more of students' everyday experience, while in actual practice they disregarded or only passively introduced students' everyday experience. The various background factors found to affect teachers' practice are as follows: positive memory on their science class; educational experience of their own children; their own childhood environment; their learning style; their insufficient knowledge or enthusiasm; perceived educational value of everyday life in science education; teacher's duties; importance of students' achievement; difficulty in guiding experiment; reaction of students on introducing everyday experience; characteristics of science textbook and teacher's guidebook; lack of lesson time; realization of national common basic education; characteristics of their students; demands from parents or students; effect of introducing everyday experience. In addition, we found that the teachers behave not in accordance with what they thought due to external factors related to their profession and that, for a more active use of students' everyday experience in their teaching, teachers need support from textbooks and teachers' guidebooks.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.993-994
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• 2008

Electrochromic (EC) devices are capable of reversibly changing their optical properties upon charge injection and extraction induced by the external voltage. The characteristics of the EC device, such as low power consumption, high coloration efficiency, and memory effects under open circuit status, make them suitable for use in a variety of applications including smart windows and electronic papers. Coloration due to reduction or oxidation of redox chromophores can be used for EC devices (e-paper), but the switching time is slow (second level). Recently, with increasing demand for the low cost, lightweight flat panel display with paper-like readability (electronic paper), an EC display technology based on dye-modified $TiO_2$ nanoparticle electrode was developed. A well known organic dye molecule, viologen, was adsorbed on the surface of a mesoporous $TiO_2$ nanoparticle film to form the EC electrode. On the other hand, ZnO is a wide bandgap II-VI semiconductor which has been applied in many fields such as UV lasers, field effect transistors and transparent conductors. The bandgap of the bulk ZnO is about 3.37 eV, which is close to that of the $TiO_2$ (3.4 eV). As a traditional transparent conductor, ZnO has excellent electron transport properties, even in ZnO nanoparticle films. In the past few years, one-dimension (1D) nanostructures of ZnO have attracted extensive research interest. In particular, 1D ZnO nanowires renders much better electron transportation capability by providing a direct conduction path for electron transport and greatly reducing the number of grain boundaries. These unique advantages make ZnO nanowires a promising matrix electrode for EC dye molecule loading. ZnO nanowires grow vertically from the substrate and form a dense array (Fig. 1). The ZnO nanowires show regular hexagonal cross section and the average diameter of the ZnO nanowires is about 100 nm. The cross-section image of the ZnO nanowires array (Fig. 1) indicates that the length of the ZnO nanowires is about $6\;{\mu}m$. From one on/off cycle of the ZnO EC cell (Fig. 2). We can see that, the switching time of a ZnO nanowire electrode EC cell with an active area of $1\;{\times}\;1\;cm^2$ is 170 ms and 142 ms for coloration and bleaching, respectively. The coloration and bleaching time is faster compared to the $TiO_2$ mesoporous EC devices with both coloration and bleaching time of about 250 ms for a device with an active area of $2.5\;cm^2$. With further optimization, it is possible that the response time can reach ten(s) of millisecond, i.e. capable of displaying video. Fig. 3 shows a prototype with two different transmittance states. It can be seen that good contrast was obtained. The retention was at least a few hours for these prototypes. Being an oxide, ZnO is oxidation resistant, i.e. it is more durable for field emission cathode. ZnO nanotetropods were also applied to realize the first prototype triode field emission device, making use of scattered surface-conduction electrons for field emission (Fig. 4). The device has a high efficiency (field emitted electron to total electron ratio) of about 60%. With this high efficiency, we were able to fabricate some prototype displays (Fig. 5 showing some alphanumerical symbols). ZnO tetrapods have four legs, which guarantees that there is one leg always pointing upward, even using screen printing method to fabricate the cathode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.122-122
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• 2008

Recently, Metal/Alumina/Silicon-Nitride/Silicon-Oxide/Silicon (MANOS) structures are one of the most attractive candidates to realize vertical scaling of high-density NAND flash memory [1]. However, as ANO layers are miniaturized, negative and positive bias temperature instability (NBTI/PBTI), such as the flat band voltage shift, ${\Delta}V_{FB}$, the interfacial trap density increase, ${\Delta}D_{it}$, the gate leakage current, ${\Delta}I_G$. and the retention characteristics, in MONOS capacitors, becomes an important issue in terms of reliability. It is well known that tunnel oxide degradation is a result of the oxide and interfacial traps generation during FN (Fowler-Nordheim) stress [2]. Because the bias temperature stress causes an increase of both interfacial-traps and fixed oxide charge could be a factor, witch can degrade device reliability during the program and erase operation. However, few studies on NBTI/PBTI have been conducted on improving the reliability of MONOS devices. In this work, we investigate the effect of post-annealing gas on bias temperature instability (BTI), such as the flat band voltage shift, ${\Delta}V_{FB}$, the interfacial trap density shift, ${\Delta}I_G$ retention characteristics, and the gate leakage current characteristics of MANOS capacitors. MANOS samples annealed at $950^{\circ}C$ for 30 s by a rapid thermal process were treated via additional annealing in a furnace, using annealing gases $N_2$ and $N_2-H_2$ (2 % hydrogen and 98 % nitrogen mixture gases) at $450^{\circ}C$ for 30 min. MANOS samples annealed in $N_2-H_2$ ambient had the lowest flat band voltage shift, ${\Delta}V_{FB}$ = 1.09/0.63 V at the program/erase state, and the good retention characteristics, 123/84 mV/decade at the program/erase state more than the sample annealed at $N_2$ ambient.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.53-63
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• 2009

This work proposes a 10b 100MS/s 27.2mW $0.8mm^2$ 0.18um CMOS ADC for WLAN such as an IEEE 802.11n standard. The proposed ADC employs a three-stage pipeline architecture and minimizes power consumption and chip area by sharing as many circuits as possible. Two multiplying DACs share a single amplifier without MOS switches connected in series while the shared amplifier does not show a conventional memory effect. All three flash ADCs use only one resistor ladder while the second and third flash ADCs share all pre-amps to further reduce power consumption and chip area. The interpolation circuit employed in the flash ADCs halves the required number of pre-amps and an input-output isolated dynamic latch reduces the increased kickback noise caused by the pre-amp sharing. The prototype ADC implemented in a 0.18um n-well 1P6M CMOS process shows the DNL and INL within 0.83LSB and 1.52LSB at 10b, respectively. The ADC measures an SNDR of 52.1dB and an SFDR of 67.6dB at a sampling rate of 100MS/s. The ADC with an active die area of $0.8mm^2$ consumes 27.2mW at 1.8V and 100MS/s.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.9
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• pp.611-615
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• 2001

Y$_2$O$_3$ thin films have been proposed as a buffering insulator of metal/ferroelectric/insulator/semiconductor field effect transistor(MFISFET)-type ferroelectric random access memory (FRAM). In this study, $Y_2$O$_3$ thin films were etched with inductively coupled plasma(ICP). The etch rates of $Y_2$O$_3$ and YMnO$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were investigated by varying Cl$_2$/(Cl$_2$＋Ar) gas mixing ratio. The maximum etch rate of $Y_2$O$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were 302$\AA$/min, and 2.4 at Cl$_2$/(Cl$_2$＋Ar) gas mixing ratio of 0.2 respectively. Optical emission spectroscopy(OES) was used to understand the effects of gas combination on the etch rate of $Y_2$O$_3$ thin film. The surface reaction of the etched $Y_2$O$_3$ thin films was investigated by x-ray photoelectron spectroscopy (XPS). XPS analysis confirmed that there was chemical reaction between Y and Cl. This result was confirmed by secondary ion mass spectroscopy(SIMS) analysis.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.27-40
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• 2020

In this paper, we investigate the correlation between the amount of English sentences that Korean English learners (L2ers) are exposed to and their sentence processing patterns by examining what Long Short-Term Memory (LSTM) language models (LMs) can learn about implicit syntactic relationship: that is, the filler-gap dependency. The filler-gap dependency refers to a relationship between a (wh-)filler, which is a wh-phrase like 'what' or 'who' overtly in clause-peripheral position, and its gap in clause-internal position, which is an invisible, empty syntactic position to be filled by the (wh-)filler for proper interpretation. Here to implement L2ers' English learning, we build LSTM LMs that in turn learn a subset of the known restrictions on the filler-gap dependency from English sentences in the L2 corpus that L2ers can potentially encounter in their English learning. Examining LSTM LMs' behaviors on controlled sentences designed with the filler-gap dependency, we show the characteristics of L2ers' sentence processing using the information-theoretic metric of surprisal that quantifies violations of the filler-gap dependency or wh-licensing interaction effects. Furthermore, comparing L2ers' LMs with native speakers' LM in light of processing the filler-gap dependency, we not only note that in their sentence processing both L2ers' LM and native speakers' LM can track abstract syntactic structures involved in the filler-gap dependency, but also show using linear mixed-effects regression models that there exist significant differences between them in processing such a dependency.