• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.917-935
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• 2020

In this study, an automated sensor to measure forest fire surface fuel moistures was developed to predict changes in the moisture content and risk of forest fire surface fuel, which was indicators of forest fire occurrence and spread risk. This measurement sensor was a method of automatically calculating the moisture content of forest fire surface fuel by electric resistance. The proxy of forest fire surface fuel used in this sensor is pine (50 cm long, 1.5 cm in diameter), and the relationship between moisture content and electrical resistance, R(R:Electrical resistance)=2E(E:Exponent of 10)+13X(X:Moisture content)-9.705(R²=0.947) was developed. In addition, using this, the software and case of the automated measurement sensor for forest fire surface fuel moisture were designed to produce a prototype, and the suitability (R²=0.824) was confirmed by performing field monitoring verification in the forest. The results of this study would contribute to develop technologies that can predict the occurrence, spread and intensity of forest fires, and are expected to be used as basic data for advanced forest fire risk forecasting technologies.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.200-207
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• 2003

'||'||'||'&'||'||'||'quot;Overheating index'||'||'||'&'||'||'||'quot;, the normalized difference in incident solar energy between a target surface and a level surface, is helpful in estimating the spatial variation in daily maximum temperature at the landscape scale. It can be computed as the ratio of the 4-hour cumulative solar irradiance surplus or deficit from that over a level surface to the maximum possible deviation (15 MJ $m^{-2}$ ) during the midafternoon. Ecosystem models may, for simplicity, use an empirical proxy (exposure index) variable combining slope and aspect in place of the overheating index to account for the variation of midafternoon solar irradiance. A comparative study with real-world landscape data was carried out to evaluate the performance of exposure index in replacing the overheating index. Overheating indices for summer solstice, fall equinox and winter solstice were calculated at 573,650 grid cells constituting the land surface of Donggye-Myun, Sunchang County in Korea, based on a 10-m DEM. Exposure index was also calculated for the same area and fitted for the variation of overheating index to derive a 2$^{nd}$ -order linear regression equation. The coefficient of determination ($R^2$) was 0.50 on summer solstice, 0.56 on fall equinox, and 0.44 on winter solstice, respectively. These are much lower than the theoretically calculated $R^2$ values ranging from 0.7 in summer to 0.9 in autumn. According to our study, exposure index failed to accurately predict the cumulative solar irradiance over a complex terrain, hindering its application to daily maximum temperature estimation. We suggest direct calculation of the overheating index in preference to using the exposure index.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.661-670
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• 2017

50-year tree-ring ${\delta}^{18}O$ chronologies (1966~2015) for principle conifer tree species (Taxus cuspidata, Pinus koraiensis, Abies koreana) and Quercus mongolica at subalpine zone in Mt. Jiri were established. The establishing of tree-ring ${\delta}^{18}O$ chronologies for each tree species were fulfilled using four trees, which showed the good result in cross-dating. In the comparisons between tree-ring ${\delta}^{18}O$ chronologies within the same tree species all tree species showed reliable results statistically (p < 0.001), and they also showed EPS higher than 0.85. In addition to, the reliable correlations (p < 0.001) were verified between tree-ring ${\delta}^{18}O$ chronologies of four tree species, as well. In the response function analysis in order to investigate the relationships between tree-ring ${\delta}^{18}O$ chronologies and corresponding climatic factors, i.e., monthly precipitation and mean temperature, T. cuspidata showed a negative correlation with May precipitation (p < 0.05) and A. koreana showed a negative correlation with April precipitation (p < 0.05). If long tree-ring ${\delta}^{18}O$ chronologies of T. cuspidata and A. koreana will be established, it will be possible to reconstruct April and May precipitation in the past when we have no the meteorological data.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.72-83
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• 2010

Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.

• Child Health Nursing Research
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• v.20 no.4
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• pp.237-246
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• 2014

Purpose: Helicopter parenting is an emerging concept as a way of rearing adolescents and adult children. However, helicopter parenting from a nursing perspective has not been elucidated. Therefore, we undertook a concept analysis to understand the attributes, antecedents and consequences of helicopter parenting in the context of nursing. Methods: Using Rodgers' evolutionary concept analysis, we analyzed literature on helicopter parenting to discover critical attributes, antecedents, and consequences of this phenomenon. Data were collected from seven electronic search engines. Twelve studies matching inclusion criteria were reviewed. Results: Three core attributes of helicopter parenting were hovering, highly deep involvement, and proxy decision making. The antecedents and consequences were retrieved from three important domains including social, parent, and child aspects. Surrogate terms were black hawk, hummingbird, and hovercraft parenting, and related terms were stealth fighter and Kamikaze parenting. Conclusion: Based on the results of this study, helicopter parenting has both positive and negative effects on both children and parents. To enhance the positive effects, measurement tools for helicopter parenting and nursing interventions on parenting need to be developed.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.34-41
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• 2011

At present wireless internet access service is available through the 3G network, mobile WiMAX and WiFi anytime and anywhere. In this environment where there are various networks, users should be able to select specific networks depending on different situations. And it is necessary to provide mobility support between homogeneous and between heterogenous networks. Given this situation, the many proposals have been presented to link 3G, which has the largest service area among various networks, with mobile WiMAX(IEEE 802.16e), or with WiFi(IEEE 802.11). But, recently, with the increasing volume of wireless internet use and wireless internet data, due to the advents of net-book, e-book and smart phone, the service area of WiFi and mobile WiMAX has rapidly expanded. Especially, the availability of real-time application such as internet phone has led to the relative shrinking of the proportion of 3G mobile communication network giving conventional voice service, and enlargement of those of wireless internet access networks like WiFi and mobile WiMAX. This paper suggests a handover scheme based on PMIPv6, whitch support mobility between WiFi and mobile WiMAX, and minimizes handover delay. In this scheme, the mobile node has a dual stack structure composed of two interfaces-WiFi and mobile WiMAX. Since WiFi dose not support mobility, it is suggested that the mobile node have the capacity to deal with handover signaling between gateway in case of handover between homogeneous networks. This handover scheme, suggested comparing with current handovers between homogeneous networks, has proved, in its analytic evaluation, to be able to reduce handover, transmission, and signaling overhead.

• Journal of agricultural medicine and community health
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• v.25 no.2
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• pp.293-302
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• 2000

The relationship between sodium intake and stomach cancer risk has been studied much in Japan but a great portions still remain controversial. There has been few studies on relationship between sodium intake and stomach cancer in Korea. The goal of this nested case-control study is to investigate the association between sodium intake and stomach cancer risk in a rural county of Korea We estimated sodium intake indirectly by the threshold of salt-water taste of patients. This study was based on both of the data from 'Kangwha Cohort Study' which had been conducted from March 1985 and 'Kangwha Community Cancer Registry' which had been launched on July in 1982 by the College of Medicine, Department of Preventive Medicine. Yonsei University. A total of 145 patients who developed stomach cancer in Kangwha County were initially recruited as the case group. We tried to get two community-controls per stomach cancer case by matching age and gender. Finally we got information from 90 cases and 146 controls about the threshold of the salt taste and preference of salty food and so on. Some 79% of the information about ease group came from proxy respondents and 56% among controls. Risk ratios of developing stomach cancer adjusted for smoking, body mass index and self-stated health level were estimated. No statistically significant association between the threshold of salt taste and stomach cancer risk found in this study. We recommend some further studies utilizing urinary salt excretion, diet record method for better estimating of salt intake with a paticular emphasis on interaction effect between salty and spicy food in hospital-based case-control study designs.

• Management & Information Systems Review
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• v.34 no.2
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• pp.193-206
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• 2015

The purposes of this paper are to investigate the impact of managers' agency problem on asymmetrical behavior of SG&C and to examines whether or not the corporate governance mechanisms can have any moderating effects on Asymmetrical behavior of SG&C. To test empirically the above mentioned purposes, we gathered firm-year data of manufacturing firms from 2007 to 2012 and the sample firms are listed on the Korean Stock Exchange. The findings of this research are summarized as follows: Firstly, for those firms whose agency problems are high, the stickiness of SG&A increases as sales variation. The results imply that managers are not willing to reduce their perquisite consumption in proportion with sales reduction. Secondly, we investigate how corporate governance mechanisms influence the cost stickiness behaviors of SG&A for those firms whose agency problem are high(above the median value of free cash flow used as a proxy of agency problem). The results are that as the effectiveness of corporate governance mechanisms improve the cost stickiness of SG&A mitigation except for the insider ownership. These results show that agency problem has impact on the asymmetrical behavior of SG&A. And effective governance mechanisms have moderate effects on the reducing stickiness behavior of SG&A caused by agency problem.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.22-29
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• 2008

The objective of this study is to provide useful information for the establishment of efficient policy implementation strategies of forest road construction policy in South Korea. Data needed for the analysis was collected by a questionnaire survey. For the analysis, policy evaluation model was constructed based on theories of public policy. Evaluation model contains three independent variables (policy initiative factor, policy content, policy environment) and two dependent variables (policy result, policy impact). Since, these variables are unobservable latent variables, observable indicators are needed as proxy measures. LISREL (Linear Structural Relationships) was employed for the analysis since it is a useful measure for analysing linear structural model which consists of structural and measurement equations. It was confirmed that forest road construction is an effective policy mean for the development of rural region and activating forest resources management. The policy outcome, however, was not satisfactory. To improve the effectiveness of forest road construction policy some modification of policy contents are needed such as increased construction budget, allowing more flexibility and participation to the implementation personal and providing technical support.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.13-23
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• 2002

The chemical compositions of groundwaters from the granite areas mainly belong to Ca-HC0$_{3}$ and Na-HC0$_{3}$type, and some of these belong to Ca-(CI+S0$_{4}$) and Na-(CI+S0$_{4}$) type. Spring waters and groundwaters from anorthosite areas belong to Ca-HC03 and Na-HC03 type, respectively. The result of reaction path modeling shows that the chemical compositions of aqueous solution reacted with granite evolve from initial Ca-CI type, via CaHC0$_{3}$ type, to Na-HC0$_{3}$ type. The result of rain water-anorthosite interaction is similar to evolution path of granite reaction and both of these results agree well with the field data. In the reaction path modeling of rain watergranite/anorthosite reaction, as a reaction is progressing, the activity of hydrogen ion decreases (pH increases). The concentrations of cations are controlled by the dissolution of rock-forming minerals and precipitation and re-dissolution of secondary minerals according to the pH. The continuous addition of granite causes the formation of secondary minerals in the following sequence; gibbsite plus hematite, Mn-oxide, kaolinite, silica, chlorite, muscovite (a proxy for illite here), calcite, laumontite, prehnite, and finally analcime. In the anorthosite reaction, the order of precipitation of secondary minerals is the same as with granite reaction except that there is no silica precipitation and paragonite precipitates instead of analcime. The silica and kaolinite are predominant minerals in the granite and anorthosite reactions, respectively. Total quantities of secondary minerals in the anorthosite reaction are more abundant than those in the granite reaction.