• Journal of Intelligence and Information Systems
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• v.20 no.2
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• pp.93-107
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• 2014

In this paper, we report what we have observed with regard to user-perspective issue clustering based on multi-layered two-mode network analysis. This work is significant in the context of data collection by companies about customer needs. Most companies have failed to uncover such needs for products or services properly in terms of demographic data such as age, income levels, and purchase history. Because of excessive reliance on limited internal data, most recommendation systems do not provide decision makers with appropriate business information for current business circumstances. However, part of the problem is the increasing regulation of personal data gathering and privacy. This makes demographic or transaction data collection more difficult, and is a significant hurdle for traditional recommendation approaches because these systems demand a great deal of personal data or transaction logs. Our motivation for presenting this paper to academia is our strong belief, and evidence, that most customers' requirements for products can be effectively and efficiently analyzed from unstructured textual data such as Internet news text. In order to derive users' requirements from textual data obtained online, the proposed approach in this paper attempts to construct double two-mode networks, such as a user-news network and news-issue network, and to integrate these into one quasi-network as the input for issue clustering. One of the contributions of this research is the development of a methodology utilizing enormous amounts of unstructured textual data for user-oriented issue clustering by leveraging existing text mining and social network analysis. In order to build multi-layered two-mode networks of news logs, we need some tools such as text mining and topic analysis. We used not only SAS Enterprise Miner 12.1, which provides a text miner module and cluster module for textual data analysis, but also NetMiner 4 for network visualization and analysis. Our approach for user-perspective issue clustering is composed of six main phases: crawling, topic analysis, access pattern analysis, network merging, network conversion, and clustering. In the first phase, we collect visit logs for news sites by crawler. After gathering unstructured news article data, the topic analysis phase extracts issues from each news article in order to build an article-news network. For simplicity, 100 topics are extracted from 13,652 articles. In the third phase, a user-article network is constructed with access patterns derived from web transaction logs. The double two-mode networks are then merged into a quasi-network of user-issue. Finally, in the user-oriented issue-clustering phase, we classify issues through structural equivalence, and compare these with the clustering results from statistical tools and network analysis. An experiment with a large dataset was performed to build a multi-layer two-mode network. After that, we compared the results of issue clustering from SAS with that of network analysis. The experimental dataset was from a web site ranking site, and the biggest portal site in Korea. The sample dataset contains 150 million transaction logs and 13,652 news articles of 5,000 panels over one year. User-article and article-issue networks are constructed and merged into a user-issue quasi-network using Netminer. Our issue-clustering results applied the Partitioning Around Medoids (PAM) algorithm and Multidimensional Scaling (MDS), and are consistent with the results from SAS clustering. In spite of extensive efforts to provide user information with recommendation systems, most projects are successful only when companies have sufficient data about users and transactions. Our proposed methodology, user-perspective issue clustering, can provide practical support to decision-making in companies because it enhances user-related data from unstructured textual data. To overcome the problem of insufficient data from traditional approaches, our methodology infers customers' real interests by utilizing web transaction logs. In addition, we suggest topic analysis and issue clustering as a practical means of issue identification.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.239-240
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• 2008

As semiconductor devices are scaled down for better performance and more functionality, the Cu-based interconnects suffer from the increase of the resistivity of the Cu wires. The resistivity increase, which is attributed to the electron scattering from grain boundaries and interfaces, needs to be addressed in order to further scale down semiconductor devices [1]. The increase in the resistivity of the interconnect can be alleviated by increasing the grain size of electroplating (EP)-Cu or by modifying the Cu surface [1]. Another possible solution is to maximize the portion of the EP-Cu volume in the vias or damascene structures with the conformal diffusion barrier and seed layer by optimizing their deposition processes during Cu interconnect fabrication, which are currently ionized physical vapor deposition (IPVD)-based Ta/TaN bilayer and IPVD-Cu, respectively. The use of in-situ etching, during IPVD of the barrier or the seed layer, has been effective in enlarging the trench volume where the Cu is filled, resulting in improved reliability and performance of the Cu-based interconnect. However, the application of IPVD technology is expected to be limited eventually because of poor sidewall step coverage and the narrow top part of the damascene structures. Recently, Ru has been suggested as a diffusion barrier that is compatible with the direct plating of Cu [2-3]. A single-layer diffusion barrier for the direct plating of Cu is desirable to optimize the resistance of the Cu interconnects because it eliminates the Cu-seed layer. However, previous studies have shown that the Ru by itself is not a suitable diffusion barrier for Cu metallization [4-6]. Thus, the diffusion barrier performance of the Ru film should be improved in order for it to be successfully incorporated as a seed layer/barrier layer for the direct plating of Cu. The improvement of its barrier performance, by modifying the Ru microstructure from columnar to amorphous (by incorporating the N into Ru during PVD), has been previously reported [7]. Another approach for improving the barrier performance of the Ru film is to use Ru as a just seed layer and combine it with superior materials to function as a diffusion barrier against the Cu. A RulTaN bilayer prepared by PVD has recently been suggested as a seed layer/diffusion barrier for Cu. This bilayer was stable between the Cu and Si after annealing at $700^{\circ}C$ for I min [8]. Although these reports dealt with the possible applications of Ru for Cu metallization, cases where the Ru film was prepared by atomic layer deposition (ALD) have not been identified. These are important because of ALD's excellent conformality. In this study, a bilayer diffusion barrier of Ru/TaCN prepared by ALD was investigated. As the addition of the third element into the transition metal nitride disrupts the crystal lattice and leads to the formation of a stable ternary amorphous material, as indicated by Nicolet [9], ALD-TaCN is expected to improve the diffusion barrier performance of the ALD-Ru against Cu. Ru was deposited by a sequential supply of bis(ethylcyclopentadienyl)ruthenium [Ru$(EtCp)_2$] and $NH_3$plasma and TaCN by a sequential supply of $(NEt_2)_3Ta=Nbu^t$ (tert-butylimido-trisdiethylamido-tantalum, TBTDET) and $H_2$ plasma. Sheet resistance measurements, X-ray diffractometry (XRD), and Auger electron spectroscopy (AES) analysis showed that the bilayer diffusion barriers of ALD-Ru (12 nm)/ALD-TaCN (2 nm) and ALD-Ru (4nm)/ALD-TaCN (2 nm) prevented the Cu diffusion up to annealing temperatures of 600 and $550^{\circ}C$ for 30 min, respectively. This is found to be due to the excellent diffusion barrier performance of the ALD-TaCN film against the Cu, due to it having an amorphous structure. A 5-nm-thick ALD-TaCN film was even stable up to annealing at $650^{\circ}C$ between Cu and Si. Transmission electron microscopy (TEM) investigation combined with energy dispersive spectroscopy (EDS) analysis revealed that the ALD-Ru/ALD-TaCN diffusion barrier failed by the Cu diffusion through the bilayer into the Si substrate. This is due to the ALD-TaCN interlayer preventing the interfacial reaction between the Ru and Si.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.365-370
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• 2012

In this study, Economic analysis of supercritical coal-fired power plant with $CO_2$ capture process was performed. For this purpose, chemical absorption method using amine solvent, which is commercially available and most suitable for existing thermal power plant, was studied. For the evaluation of the economic analysis of coal-fired power plant with post-combustion $CO_2$ capture process in Korea, energy penalty after $CO_2$ capture was calculated using the power equivalent factor suggested by Bolland et al. And the overnight cost of power plant (or cost of plant construction) and the operation cost reported by the IEA (International Energy Agency) were used. Based on chemical absorption method using a amine solvent and 3.31 GJ/$tonCO_2$ as a regeneration energy in the stripper, the net power efficiency was reduced from 41.0% (without $CO_2$ capture) to 31.6% (with $CO_2$ capture) and the levelized cost of electricity was increased from 45.5 USD/MWh (Reference case, without $CO_2$ capture) to 73.9 USD/MWh (With $CO_2$ capture) and the cost of $CO_2$ avoided was estimated as 41.3 USD/$tonCO_2$.

• Korean Journal of Environment and Ecology
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• v.26 no.1
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• pp.46-56
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• 2012

Benthic macroinvertebrates were investigated in Hoeongseong Lake region from March to October 2010, Korea. Macroinvertebrate communities, composition of the functional feeding groups, habitiat oriented groups and the biological water quality were assessed above and below Hoeongseong Dam in the lake region. Six sites, two (St.1~2) above the lake, two (St. 3~4) into the lake, and two (St. 5~6) below the dam, were selected for quantitative (Surber sampler $30cm{\times}30cm$, mesh size 0.2 mm) and qualitative (Hand net) samplings of benthic macroinvertebrates. As a result, a total of 83 species belonging to 43 families, 17 orders, 8 classes, and 5 phyla were recognized. The EPT-group (50 spp. : 60.24%) that is major taxa or EPT-group plus Diptera (61 spp. : 73.49%) occupied most of benthic macroinvertebrates community. Based on quantitative sampling, the number of benthic maroinvertebrates above the lake was 2,399 individuals including 54 species, 28 families, 11 orders, 4 classes, and 4 phyla, whereas 510 individuals including 16 species, 12 families, 7 orders, 4 classes, and 3 phyla in the lake and 626 individuals including 62 species, 33 families, 13 orders, 6 classes, and 4 phyla below the dam were collected respectively. Dominance index was the highest, with 0.82-0.93 ($0.87{\pm}0.05$) in Hoeongseong lake (St. 3-4), diversity index was 3.04-3.16 ($3.10{\pm}0.06$), evenness index was 0.79-0.85 ($0.82{\pm}0.03$), and richness index was 7.27-8.52 ($7.90{\pm}0.63$), which were relatively higher below the dam sites. In the functional feeding groups, collector-gatherers and collector-filterers were the highest in the whole sites, and predators (Micronecta sedula) was appeared highly in the lake. Moreover, swimmers, burrowers, and clingers were considerably occupied in all collecting sites. The result of the DCA, similarity analysis, and MRPP were well reflective of the composition of lake and stream macroinvertebrates. ESB indicate that the lake sites were evaluated heavily polluted under priority improvement waters. Also, Semisulcospira gottschei, Ecdyonurus kibunensis, Epeorus pellucidus, Rhoenanthus coreanus, Stenelmis sp., and Cheumatopsyche brevilineata are considered as an indicator species above and below Hoeongseong Lake, whereas Macrobrachium nipponense and Micronecta sedula are indicated in the lake.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.387-394
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• 2017

Temperature-dependent oviposition model and life table parameters of Paromius exiguus (Distant), the causal agent of 'pecky' rice grain were examined at eight constant temperatures (17.5, 20, 22.5, 25, 27.5, 30, 32.5, and $35{\pm}^{\circ}C$) and a photoperiod of 14:10 (L:D) h. Unit functions of the oviposition model were developed and life table parameters were estimated. The longevity of P. exiguus adults decreased with increasing temperature (123.8 days at $17.5^{\circ}C$ and 23.6 days at $32.5^{\circ}C$). Total fecundity was highest at $30^{\circ}C$ (585.2 eggs/female) and lowest at $17.5^{\circ}C$ (21.5 eggs/female). In order to develop a temperature-dependent oviposition model, adult aging-rate, temperature-dependent fecundity, age-specific survival rate, and age-specific cumulative oviposition rate equations were estimated. All unit equations ($r^2=0.92{\sim}0.98$) except for the temperature-dependent fecundity equation ($r^2=0.83{\sim}0.85$), described oviposition characteristics of P. exiguus adequately. Life table parameters of P. exiguus were estimated at various constant temperatures. Net reproduction rate ($R_0$) was highest at $30^{\circ}C$ (118.21). Mean generation time (T) was shortest at $32.5^{\circ}C$ (32.99 days) and doubling time (Dt) was shortest at $30^{\circ}C$ (5.69 days). The highest values of intrinsic rate of increase ($r_m$) and finite rate of increase (${\lambda}$) were 0.122 and 1.129 at $30^{\circ}C$, respectively.

• Journal of Bio-Environment Control
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• v.29 no.2
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• pp.171-180
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• 2020

The effect of three different light qualities on growth, photosynthesis, quality and safe parameters of hydroponic cultivated spinach (Spinacia oleracea L.) were investigated indoor. Three different light qualities were created of red (660 nm), blue (450 nm) and green (550 nm) LEDs corresponding at ratio R660/B450 = 4/1 (RBL); R660/B450/G550= 5/2/3 (WWL); R660/B450/G550 = 1/1/1 (WL), which were tested at the same intensity (PPFD =190 μmol m^-2 s^-1). The results showed that the plant height and leaf number were the lowest in WL treatment. The SPAD, Net photosynthesis rate Pn, Fv/Fm, Leaf area index LAI values and all parameters of root characteristics were the highest in RBL treatment and were significantly different from two others. Fresh weight of stem, leaf and root, dry weight of root in the three light qualities were significantly different. In contrast, the highest K⁺ content in WL was different from WWL and RBL treatments, while Ca²⁺ and Fe²⁺ content were the highest in the RBL treatment. Vitamin C content was significantly different between the three treatments. nitrate and oxalic acid contents were the highest in WL treatment, whereas soluble-solids contents and vitamin C contents were the highest in RBL treatment. Oxalic acid, nitrate contents were observed tending reduced under WWL although oxalic acid content in RBL treatment was not different from WL and WWL treatments. In all three different light treatments were not detected Salmonella, E.coli. Our results suggest that RBL may be appropriate light for growth of spinach, but supplementary green light to a combination of red and blue LEDs at the reasonable rate can change the quality of spinach in a positive direction. Hydroponic cultivated spinach was safe for users.

• Asian Journal of Turfgrass Science
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• v.24 no.1
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• pp.16-23
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• 2010

Mowing is an important practice in golf course management. Mowing interval and height can affect net photosynthesis of turfgrass and finally shoot density, tillering, rooting and regrowth of turfgrass. The objectives of this study were to investigate the regrowth rate of zoysiagrass shoot under different mowing height for determination of proper mowing frequency. Recommended mowing interval were calculated by a rule that no more than 33% of the above ground height be removed in a single mowing. Daily shoot growth of zoysiagrass at 10 mm mowing height were 2.1~4.7 mm (July), 1.9~2.9 mm (August), 0.9~1.5 mm (September), and 0.6 mm (October). These results indicate that recommended mowing interval were 1.1~2.3 day for July, 1.7~2.4 day for August, 3.5~5.4 day for September, and 8.5 day for October, respectively. Daily shoot growth of zoysiagrass at 15 to 17 mm mowing height were 4.0~5.3 mm (July), 2.9~4.5 mm (August), 1.4~3.7 mm (September), and 1.3 mm (October). These results indicate that recommended mowing interval were 1.4~1.9 day for July, 1.7~2.5 day for August, 2.3~6.3 day for September, and 6.8 day for October, respectively. Daily shoot growth of zoysiagrass at 18 to 21 mm mowing height were 3.5~4.7 mm (July), 2.9~4.9 mm (August), and 1.5~1.8 mm (September). These results indicate that recommended mowing interval were 1.9~2.6 day for July, 1.8~3.1 day for August, and 5.9~7.0 day for September, respectively. Daily shoot growth of zoysiagrass at 50 mm mowing height were 4.6~4.9 mm (July), 5.0~6.5 mm (August), and 2.5~4.7 mm (September). These results indicate that recommended mowing interval were 5.1~5.4 day for July, 3.9~5.0 day for August, and 5.3~9.8 day for September, respectively.

• Progress in Medical Physics
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• v.13 no.3
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• pp.149-155
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• 2002

Recent advances in radiation transport algorithms, computer hardware performance, and parallel computing make the clinical use of Monte Carlo based dose calculations possible. To compare the speed and accuracies of dose calculations between different developed codes, a benchmark tests were proposed at the XIIth ICCR (International Conference on the use of Computers in Radiation Therapy, Heidelberg, Germany 2000). A Monte Carlo treatment planning comprised of 28 various Intel Pentium CPUs was implemented for routine clinical use. The purpose of this study was to evaluate the performance of our system using the above benchmark tests. The benchmark procedures are comprised of three parts. a) speed of photon beams dose calculation inside a given phantom of 30.5 cm$\times$39.5 cm $\times$ 30 cm deep and filled with 5 ㎣ voxels within 2% statistical uncertainty. b) speed of electron beams dose calculation inside the same phantom as that of the photon beams. c) accuracy of photon and electron beam calculation inside heterogeneous slab phantom compared with the reference results of EGS4/PRESTA calculation. As results of the speed benchmark tests, it took 5.5 minutes to achieve less than 2% statistical uncertainty for 18 MV photon beams. Though the net calculation for electron beams was an order of faster than the photon beam, the overall calculation time was similar to that of photon beam case due to the overhead time to maintain parallel processing. Since our Monte Carlo code is EGSnrc, which is an improved version of EGS4, the accuracy tests of our system showed, as expected, very good agreement with the reference data. In conclusion, our Monte Carlo treatment planning system shows clinically meaningful results. Though other more efficient codes are developed such like MCDOSE and VMC＋＋, BEAMnrc based on EGSnrc code system may be used for routine clinical Monte Carlo treatment planning in conjunction with clustering technique.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2002.11a
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• pp.29-30
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• 2002

The goal of this research was to develop the effectiveness of in vitro culture method for A. formosanus and study the environment in vitro conditions affecting on growth. The first series of experiments were examined to investigate the response of three different basal media, MS (Murashige and Skoog, 1962), Knudson (KC; Knudson, 1946) and modified hyponex on growth and multiplication during in vitro culture. Multiple shoot proliferation was induced in shoot tip explants on Hyponex (H3) media supplemented with BA (1 mg1$\^$-1/) or TDZ (1-2 mg1$\^$-1/). Addition of activated charcoal (1%) to the TDZ containing medium promoted rapid shoot tip proliferation (11.1 shoots per explant) but the same medium had an opposite effect resulting in poor proliferation in the nodal explants. However, the regenerated shoots had slow growth rate and failed to elongate. This problem was overcome by transferring the shoot clumps to a hormone free H3 media supplemented with 2% sucrose and 0.5% activated charcoal. Using bioreactor culture for scaling up was also shown the best way for multiple shoot induction and growth of this plant. The second series of experiments was studied to investigate the effect of physical environment factors on growth of in vitro plantlets. The Anoectochilus formosanus plantlets were cultured under different air exchange rate (0.1, 0.9, 1.2h$\^$-1/), without sucrose or supplement 20g.1$\^$-1/ (photoautotrophic or photomixotrophic, respectively), and different photosynthesis photon flux (40, 80, 120 ,${\mu}$mol.m$^2$.s$\^$-1/- PPF). Under non-enrichment CO$_2$ treatment, slow growth was observed in photoautotrophical condition as compared with photomixotrophical condition on shoot height, fresh weigh and dry weight parameters; High air exchange (1.2.h-l) was found to be inadequate for plant growth in photomixotrophical condition. On the contrary, under CO$_2$, enrichment treatment, the plant growth parameters were sharply (visibly) improved on photoautotrophic treatments, especially on the treatment with air exchange rate of 0.9.h-1. The growth of plant in photoautotrophic condition was not inferior compared with photomixotrophic, and the best growth of plantlet was observed in treatment with low air exchange rate (0.9.h-1). Raising the PPF level from 80 to 120${\mu}$mol.m$\^$-2/.s$\^$-1/ decreased the plant height, particularly at 120${\mu}$mol.m$\^$-2/.s$\^$-1/ in photoautotrophic condition, fresh weight and dry weight declined noticeably. At the PPF of 120${\mu}$mol.m$\^$-2/,s$\^$-1/, chlorophyll contents lowed compared to those grown under low PPF but time courses of net photosynthesis rate was decreased noticeably. Light quality mainly affected morphological variables, changes of light quality also positively affected biomass production via changes in leaf area, stem elongation, chlorophyll content. Plant biomass was reduced when A. formosanus were grown under red LEDs in the absence of blue wavelengths compare to plants grown under supplemental blue light or under fluorescent light. Stem elongation was observed under red and blue light in the present experiment. Smaller leaf area has found under blue light than with other lighting treatments. Chlorophyll degradation was more pronounced in red and blue light compared with white light or red plus blue light which consequent affected the photosynthetic capacity of the plant. The third series of experiment were studied to investigate the effect of physical environment factors on growth of ex vitro plants including photosynthesis photon flux (PPF), light quality, growing substrates, electrical conductivity (EC) and humidity conditions. In the present experiments, response of plant on PPF and light quality was similar in vitro plants under photosynthesis photon flux 40${\mu}$mol.m,$\^$-2/.s$\^$-1/ and white light or blue plus red lights were the best growth. Substrates testing results were indicated cocopeat or peat moss were good substrates for A. formosanus growth under the greenhouse conditions. In case of A. formosanus plants, EC is generally maintained in the range 0.7 to 1.5 dS.m-1 was shown best results in growth of this plant. Keeping high humidity over 70% under low radiation enhanced growth rate and mass production.

• Korean journal of applied entomology
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• v.37 no.2
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• pp.143-149
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• 1998

Development and life table statistics of indian meal moth (Plodia interpunctella, Hiibner)on brown rice (Sativa oryzae L., var 'Ilpum' ) were tested under five different temperatures (17, 20, 25,28 and 3 2 f 0.5"C). The developmental response of females to the temperature was not significantlydifferent from that of males. In the tested temperature range, developmental period and life span of adultmoth decreased as the temperature increased and ranged from 149.9f30.4 to 38.1 k5.6 days and from19.4f 5.1 to 6.9k2.0 days at 17$^{\circ}$C and 32"C, respectively. Emergence rate increased with the increaseof temperature and ranged from 13.0f 6.2% at 17$^{\circ}$C to 49.2f 25.9% at 32$^{\circ}$C. However, hatching ratecurve in relation to the temperature was dome shape with the peak of 73.8 k5.37~a t 25"C, suggesting thathatching is inhibited by high temperature above that temperature. As the temperature increased, femalesconcentrated their oviposition on the second day after emergence. In the temperature range of 17 SIM 25"C, the number of eggs laid per female were not related to the temperature and ranged from 133.4f 37.6to 154.3k57.4. But the number of eggs laid per female decreased at 32$^{\circ}$C which suggests closerelationship with hatching ability. The net reproduction rate was highest at 28$^{\circ}$C and followed by those at25$^{\circ}$C and 20$^{\circ}$C. However intrinsic rate of natural increase of the moth population on brown rice wasestimated to be highest at 32$^{\circ}$C (0.065 per day), probably due to the short developmental period, highemergence rate and the concentrated oviposition of females on earlier days of the emergence.ition of females on earlier days of the emergence.