• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.2
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• pp.33-40
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• 2014

The purpose of this study is to examine vegetation of the outer walls of the Jeongyi Town Wall in Jeju and analyze the characteristics and problems identified, for suggesting preliminary data for selecting species of plants appropriate for the greening of the walls in the southern temperate climate region, including Jeju. The result of this study is as follows. The number of plants growing naturally around the walls of the town was identified to be 52 taxa. Based on the list of naturalized plants, there are 5 taxa; Sonchus oleraceus, Houttuynia cordata, Crassocephalum crepidioides, Erigeron annuus and Lamium purpureum. The number of species by district was from 3 to 14 taxa with 7.1 taxa on average. Analyzing by the constancy class, plants in class III included Sedum bulbiferum, Trichosanthes kirilowii, Hedera rhombea and Boehmeria nivea. Manipulation of the species composition table shows that the number of plant species growing naturally around the walls of Jeongyi Town Wall is a total of 52 taxa, including 11 taxa by differential species of community and 41 taxa by companion species. The types of plants very useful for the covering of the walls are evergreen climbing vine, such as Hedera rhombea, Ficus thunbergii and Euonymus fortunei and deciduous climbing vine, such as Parthenocissus tricuspidata, Trichosanthes kirilowii and Paederia scandens. In addition, Ficus stipulata is identified as a vegetation more appropriate for the southern-ward lattice-blocked walls. Woody plants, such as Akebia quinata, Celastrus flagellaris, Ampelopsis brevipedunculata for. citrulloides, Rubus hirsutus, Clematis apiifolia and herbaceous plants, such as Dioscorea tenuipes, D. quinqueloba, D. nipponica, Cayatia japonica and Paederia scandens var. angustifolia are highly useful materials for climbing plants for covering the walls of the southern province. Pteridophyte, such as Lemmaphyllum microphyllum, Pteris multifida, Cyrtomium falcatum and Lygodium japonicumare suggested as very useful for increasing unique regional characteristics of the southern province, including Jeju.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.77-88
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• 2000

In this paper, the 3-mode variable gain high power amplifier for a transmitter of INMARSAT-B operating at L-band(1626.5-1646.5 MHz) was developed. This SSPA can amplify 42 dBm in high power mode, 38 dBm in medium power mode and 36 dBm in low power mode for INMARSAT-B. The allowable errol sets +1 dBm as the upper limit and -2 dBm as the lower limit, respectively. To simplify the fabrication process, the whole system is designed by two parts composed of a driving amplifier and a high power amplifier. The HP's MGA-64135 and Motorola's MRF-6401 were used for driving amplifier, and the ERICSSON's PTE-10114 and PTF-10021 for the high power amplifier. The SSPA was fabricated by the RP circuits, the temperature compensation circuits and 3-mode variable gain control circuits and 20 dB parallel coupled-line directional coupler in aluminum housing. In addition, the gain control method was proposed by digital attenuator for 3-mode amplifier. Then il has been experimentally verified that the gain is controlled for single tone signal as well as two tone signals. In this case, the SSPA detects the output power by 20 dB parallel coupled-line directional coupler and phase non-splitter amplifier. The realized SSPA has 41.6 dB, 37.6 dB and 33.2 dB for small signal gain within 20 MHz bandwidth, and the VSWR of input and output port is less than 1.3:1. The minimum value of the 1 dB compression point gets more than 12 dBm for 3-mode variable gain high power amplifier. A typical two tone intermodulation point has 36.5 dBc maximum which is single carrier backed off 3 dB from 1 dB compression point. The maximum output power of 43 dBm was achieved at the 1636.5 MHz. These results reveal a high power of 20 Watt, which was the design target.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.53-62
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• 2018

Follofwing the accelerating speed-up of trains and rising demand for large-volume transfer capacity, not only in Korea, but also around the world, track structures for trains have been improving consistently. Precast concrete slab track (PST), a concrete structure track, was developed as a system that can fulfil new safety and economic requirements for railroad traffic. The purpose of this study is to provide the information required for the development and design of the system in the future, by analyzing the behavior of each structural member of the PST system. The stress distribution result for different combinations of appropriate loads according to the KRL-2012 train load and KRC code was analyzed by conducting a three-dimensional finite element analysis, while the result for different thicknesses of the grouting layer is also presented. Among the structural members, the largest stress took place on the grouting layer. The stress changed sensitively following the thickness and the combination of loads. When compared with a case of applying only a vertical KRL-2012 load, the stress increased by 3.3 times and 14.1 times on a concrete panel and HSB, respectively, from the starting load and temperature load. When the thickness of the grouting layer increased from 20 mm to 80 mm, the stress generated on the concrete panel decreased by 4%, while the stress increased by 24% on the grouting layer. As for the cracking condition, tension cracking was caused locally on the grouting layer. Such a result indicates that more attention should be paid to the flexure and tension behavior from horizontal loads rather than from vertical loads when developing PST systems. In addition, the safety of each structural member must be ensured by maintaining the thickness of the grouting layer at 40 mm or more.

• Journal of Conservation Science
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• v.31 no.1
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• pp.37-46
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• 2015

In the case of adhesives & restoration agents currently being used for the preservation treatment of ceramics and earthenware, epoxy type, cellulose type and cellulose type are mainly being used. However, they are showing various problems such as re-detachment from severe contraction, color change from yellowing, work inconvenience of staining on tools and hand during usage and irreversibility. For the purpose of solving the issues of yellowing and irreversibility of epoxy resin being used to restore ceramics, urethane synthetic resin with low yellowing excellent reversibility has been developed in this study. The adhesive strength of urethane resin that has been developed has excellent properties with 2.07MPa for undiluted solution, which is 1.5 times higher than that of existing material EPO-$TEK301^{(R)}$ 1.21MPa. The result of workability measurement showed that the wear rate of urethane resin (in Talc 50wt%) was 1.09%, which was somewhat higher than that of existing material Quick $Wood^{(R)}$ (1.02%). In addition, its wear rate is two times higher than that of $EPO-TEK301^{(R)}$ (0.41%) and $L30^{(R)}$ (0.39%), thereby showing an advantage in its forming process compared to existing materials. As for the advantage of urethane resin of reversibility experiment, 12 hours after acetone, ethyl alcohol deposition, urethane resin and filler talc were dissolved 100% while showing powdering phenomenon. Compared to 0% reversibility of existing epoxy resin, it has much superior reversibility. The result of UV rays experiment to evaluate its durability showed that ${\Delta}E^*ab$ color change value based on undiluted solution of urethane resin was 2.76 before & after UV rays exposure, which was a decrease by about 7-20 times compared to that of existing resin, thereby minimizing the issue of heterogeneity.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.101-108
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• 1993

$TiO_{2}$/Se : Te heterojunction for color sensor has been fabricated by RF reactive sputtering and thermal evaporation methods onto glass substrate. The optimum deposition condition of $TiO_{2}$ films was such that RF power was 120 W, substrate temperature was $100^{\circ}C$, oxygen concentration was 50%, working pressure was 50 mTorr for the $TiO_{2}$ film thickness of $1000{\AA}$. In this case, the optical transmittance of $TiO_{2}$ film at 550 nm-wavelength was 85%, resistivity was $2{\times}10^9{\Omega}{\cdot}cm$, refractive index was 2.3, and optical bandgap was 3.58 eV. The composition ratio of 0 to Ti by AES analysis was 1.7. When $TiO_{2}$ films were annealed at $400^{\circ}C$ for 30 min. in $O_{2}$ ambient, the optical transmittance of $TiO_{2}$ films at the wavelength range of $300{\sim}580$ nm was improved from 0 to 25%. When Se : Te films were annealed at $190^{\circ}C$ for 1 min., photosensitivity under illumination of 1000 lux was 0.75. The optical bandgap of Se : Te films was 1.7 eV. The structures of Se : Te films were the hexagonal with (100) and (110) orientation. The spectral response of a-Se was improved by the addition of Te, especially in the long wavelength region. The $TiO_{2}$/Se : Te heterojunction showed wide spectral response, and more improved one than that of a-Si film in the blue light region.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.257-271
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• 2002

One of the main interests in relation to heavily contaminated gully-pot sediment in urban area is the short term mobility of heavy metals, which depends on the pH of acidic rainwater and on the buffering effects of carbonate minerals. The buffering effects of carbonates are determined by titration (acid addition). Leaching experiments are carried out in solutions with variable initial HN03 contents for 24h. The gully-pot sediment appears to be predominantly buffered by calcite and dolomite. In case of sediment samples, which highly contain carbonates, pH decreases more slowly with increasing acidity. On the other hand, for the sediment samples, which less contain carbonate minerals, pH rapidly drops until it reaches about 2 then it decreases slowly. The leaching reactions are delayed until more acid is added to compensate for the buffering effects of carbonates. The Zn, Cu, Pb and Mn concentrations of leachate rapidly increase with decreased pH, while Cd, Co, Ni, Cr and Fe dissolutions are very slow and limited. The solubility of heavy metals depends not only on thc pH values of leachatc but also on the speciation in which metals are associated with sediment particles. In slightly to moderately acid conditions, Zn, Cd, Co, Ni and Cu dissolutions become increasingly important. As deduced from leaching runs, the relative mobility of heavy metals at pH of 5 is found to be: Zn > Cd > Co > Ni > Cu » Pb > Cr, suggesting that moderately acid rainwater leach Zn, Cd, Co, Ni and Cu from thc contaminated gully-pot sediment, while Pb and Cr would remain fixed. The buffering effects of Ca- and Mg-carbonates play an important role in delaying as well as limiting the leaching reactions of heavy metals from highly contaminated gully-pot sediment. The extent of such a secondary environmental pollution will thus depends on how well the metals in sediment can be leached by somewhat acidic rain water. Changes in the physicochemical environments may result in the severe environmental pollution of heavy metals. These results are to be taken into account in the management of contaminated sediments during rainstorms.

• Archives of design research
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• v.19 no.2 s.64
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• pp.323-332
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• 2006

Information devices such as a cellular phone, smart phone, and PDA become smaller to such an extent that people put them into their pockets without any difficulties. This drastic miniaturization causes to deteriorate the readability of text-based contents. The morphological characteristics of size and proportion are supposed to have close relationships with the pocketability and text readability of mobile information devices. This research was aimed to investigate the optimal morphological characteristics to satisfy the two usability factors together. For this purpose, we conducted an controlled experiment, which was designed to evaluate the pocketability according to $size(4000mm^2/8000mm^2)$, proportion(1:1/2:1/3:1), and weight(100g/200g) of information devices as well as participants' pose and carrying method. In the case of male participants putting the models of information device into their pockets, 2:1 morphological proportion was preferred. On the other hand, the female participants carrying the models in their hands preferred 2:1 proportion$(size:4000mm^2{\times}2mm)$ and 3:1 proportion$(size:8000mm^2{\times}20mm)$. For the device in the size of $4000mm^2$, it was found that the weight of device has an significant effect on pocketability. In consequence, 2:1 proportion is optimal to achieve better pocketability. The second experiment was about how text readability is affected by size $(2000mm^2/4000mm^2/8000mm^2)$ and proportion(1:1/2:1/3:1) of information devices as well as interlinear space of displayed text(135%/200%). From this experiment result, it was found that reading speed was increased as line length increased. Regarding the subjective assessment on reading task, 2:1 proportion was strongly preferred. Based on these results, we suggest 2:l proportion as an optimal proportion that satisfy pocketability of mobile information devices and text readability displayed on the screen together. To apply these research outputs to a practical design work efficiently, it is important to take into account the fact that the space for input devices is also required in addition to a display screen.

• Journal of Nutrition and Health
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• v.50 no.1
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• pp.85-97
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• 2017

Purpose: This study was conducted to investigate dietary habits related to weight reduction and snack intake habits of $4^{th}$ to $5^{th}$ grade elementary students located in Jeju-si, Jeju, South Korea. Methods: The $4^{th}$ and $5^{th}$ grade elementary school students (total n = 234, equally matched numbers of normal weight children and overweight/obese children (n = 117/group)) were surveyed using a questionnaire and a 24-hour dietary recall method in Oct 2015. Results: The percentage of students who experienced reduced food intake to control weight was 26.3% in the normal weight group (NG) and 77.6% in the obese group (OG). Most frequently answered meal for reduced intake was snacks in the NG and dinner in the OG. Percentages of daily calorie intake among subjects were 17.2% for breakfast, 33.8% for lunch, 29.7% for dinner, and 19.3% for snacks. Frequency of snack intake was 2.1 times a week in NG and 1.6 times a week in OG, which showed a statistical difference between body weight groups. Types of snack foods were distinctly different depending on where children consumed them, although no difference was observed between NG and OG. In addition, snack intake level of low energy and nutrient-dense foods was significantly lower in the OG compared to the NG, whereas snack intake level of energy dense and low-nutritive foods was not different between the OG and NG. Conclusion: Taken together, snack intake level with consideration of frequency and amount of snack intake showed that children in the OG consumed significantly less low energy and nutrient-dense foods compared to the NG. Therefore, nutritional education for choosing healthy snack foods for children regardless of body weight status is crucial based on family-school links.

• Journal of Intelligence and Information Systems
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• v.18 no.1
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• pp.23-38
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• 2012

There is a large difference between purchasing patterns in an online shopping mall and in an offline market. This difference may be caused mainly by the difference in accessibility of online and offline markets. It means that an interval between the initial purchasing decision and its realization appears to be relatively short in an online shopping mall, because a customer can make an order immediately. Because of the short interval between a purchasing decision and its realization, an online shopping mall transaction usually contains fewer items than that of an offline market. In an offline market, customers usually keep some items in mind and buy them all at once a few days after deciding to buy them, instead of buying each item individually and immediately. On the contrary, more than 70% of online shopping mall transactions contain only one item. This statistic implies that traditional data mining techniques cannot be directly applied to online market analysis, because hardly any association rules can survive with an acceptable level of Support because of too many Null Transactions. Most market basket analyses on online shopping mall transactions, therefore, have been performed by expanding the co-occurrence criteria of traditional association rule mining. While the traditional co-occurrence criteria defines items purchased in one transaction as concurrently purchased items, the expanded co-occurrence criteria regards items purchased by a customer during some predefined period (e.g., a day) as concurrently purchased items. In studies using expanded co-occurrence criteria, however, the criteria has been defined arbitrarily by researchers without any theoretical grounds or agreement. The lack of clear grounds of adopting a certain co-occurrence criteria degrades the reliability of the analytical results. Moreover, it is hard to derive new meaningful findings by combining the outcomes of previous individual studies. In this paper, we attempt to compare expanded co-occurrence criteria and propose a guideline for selecting an appropriate one. First of all, we compare the accuracy of association rules discovered according to various co-occurrence criteria. By doing this experiment we expect that we can provide a guideline for selecting appropriate co-occurrence criteria that corresponds to the purpose of the analysis. Additionally, we will perform similar experiments with several groups of customers that are segmented by each customer's average duration between orders. By this experiment, we attempt to discover the relationship between the optimal co-occurrence criteria and the customer's average duration between orders. Finally, by a series of experiments, we expect that we can provide basic guidelines for developing customized recommendation systems. Our experiments use a real dataset acquired from one of the largest internet shopping malls in Korea. We use 66,278 transactions of 3,847 customers conducted during the last two years. Overall results show that the accuracy of association rules of frequent shoppers (whose average duration between orders is relatively short) is higher than that of causal shoppers. In addition we discover that with frequent shoppers, the accuracy of association rules appears very high when the co-occurrence criteria of the training set corresponds to the validation set (i.e., target set). It implies that the co-occurrence criteria of frequent shoppers should be set according to the application purpose period. For example, an analyzer should use a day as a co-occurrence criterion if he/she wants to offer a coupon valid only for a day to potential customers who will use the coupon. On the contrary, an analyzer should use a month as a co-occurrence criterion if he/she wants to publish a coupon book that can be used for a month. In the case of causal shoppers, the accuracy of association rules appears to not be affected by the period of the application purposes. The accuracy of the causal shoppers' association rules becomes higher when the longer co-occurrence criterion has been adopted. It implies that an analyzer has to set the co-occurrence criterion for as long as possible, regardless of the application purpose period.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.2
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• pp.40-55
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• 2015

This study aims to evaluate the efficiency of the forest experience center for children led by the local community as experiential management for forest kindergarten education. For this, an importance and performance analysis was conducted on the forest experience center for children in Geumcheon-gu, which, of the 12 forest experience center for kids in Seoul, is the only one led by the local community. The questionnaire sheet for the analysis consisted of a total of 36 questions, 20 about place facility areas and 16 about management program areas(including 6 questions about the management led by the local community). The questionnaire survey was done during the period between January 12th and January 19th, 2015. The participants in the survey consisted of 15 forest education specialists and 50 teachers from 19 kindergartens who participated in the forest experience program. The number of questionnaire sheets collected and used for analysis was 13 copies and 43 copies, respectively. The mean values of importance and performance on the place facility areas were 4.07 and 3.78 for forest education specialists, and 4.16 and 3.84 for kindergarten teachers, respectively. The mean values of importance and performance regarding the management program area were 4.38 and 4.16 for forest education specialists, and 4.40 and 4.00 for kindergarten teachers, respectively. Both groups evaluated the place facility areas lower than the management program areas. They also evaluated performance lower than importance. In place facility area, 'accessibility', 'safety' and 'connectivity to forest trail', 'loose parts' and 'safety facilities' were required to 'keep up the good work', because they showed higher importance and performance in place facility areas. Even though most items of management as led by the local community including 'forest experience activity support' were evaluated as 'important', some, including 'effort for local revitalization', were evaluated as low in performance. However, as they were evaluated as higher in importance, if they pursue 'concentrate here', it is expected that they will be evaluated as higher in performance. In addition, considering that program areas including 'forest education specialist's role' are labeled under the management led by the local community, it reflected a positive evaluation. As a result, management led by the local community is efficient as a management system for the forest experience center for children in an experiential forest kindergarten education. Going forward, if this management system is durable in 'keep up the good work' and 'concentrate here', the forest experience center for children led by the local community will be an alternative for an effective experiential forest kindergarten education.