• Korean Journal of Remote Sensing
• /
• v.32 no.4
• /
• pp.365-382
• /
• 2016

The results from the Global Positioning System (GPS) measurements of the Mobile Observation Vehicle (MOVE) on the eastern coast of Korea have been compared with REFerence (REF) values from the fixed GPS sites to assess the performance of Precipitable Water Vapor (PWV) retrievals in a kinematic environment. MOVE-PWV retrievals had comparatively similar trends and fairly good agreements with REF-PWV with a Root-Mean-Square Error (RMSE) of 7.4 mm and $R^2$ of 0.61, indicating statistical significance with a p-value of 0.01. PWV retrievals from the June cases showed better agreement than those of the other month cases, with a mean bias of 2.1 mm and RMSE of 3.8 mm. We further investigated the relationships of the determinant factors of GPS signals with the PWV retrievals for detailed error analysis. As a result, both MultiPath (MP) errors of L1 and L2 pseudo-range had the best indices for the June cases, 0.75-0.99 m. We also found that both Position Dilution Of Precision (PDOP) and Signal to Noise Ratio (SNR) values in the June cases were better than those in other cases. That is, the analytical results of the key factors such as MP errors, PDOP, and SNR that can affect GPS signals should be considered for obtaining more stable performance. The data of MOVE can be used to provide water vapor information with high spatial and temporal resolutions in the case of dramatic changes of severe weather such as those frequently occurring in the Korean Peninsula.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.73-81
• /
• 2003

The construction industry has been experiencing a major challenge in its work force, 'the shortage of skilled craft workers.' This problem has been caused by several factors such as the poor image of the construction industry, lack of training and education, unclear career path, declining wages, and changing work force demographics. A 'step-change' approach called the 'Two-Tier Work Force Strategy' has been proposed by the Center for Construction Industry Studies (CCIS) to deal with the work force related issues in a radical way. It is composed of two separate strategies, Tier I and II. The Tier I strategy uses less skilled and task trained craft workers, and has a larger administrative site management team than the Tier II strategy. The Tier II strategy utilizes fewer, better-educated, and higher skilled workers who perform some lower-management functions in addition to craft functions. They are paid more, but produce more through higher skills, stay on the job longer through multi-skilling, and deliver improved project performance in safety, quality, schedule, and cost The Two-Tier Work Force Strategy has the potential to resolve the current work force problems and foster a better work force environment in the future.

• Journal of Broadcast Engineering
• /
• v.12 no.2
• /
• pp.148-158
• /
• 2007

Recently, IEEE 802.15.4a(low-rate UWB) technique has been paid much attention to the LR-UWB communication system for WPAN. However, there are various interferences such as MPI(Multi Path Interference) or IPI(Inter Piconet Interference) in IEEE 802.15.4a wireless channel. In order to cancel various interferences occurred to WPAN environment, in this paper, we propose a UWB wireless communication system with high QoS(Quality of Service) which is a chaotic-OOK(On-Off Keying) system using unipolar ZCD(Zero Correlation Duration) spreading code in physical layer level. Furthermore, we analyze its performance via simulations and verify the availability of proposed system with prototype implementation.

• Journal of Broadcast Engineering
• /
• v.10 no.2
• /
• pp.210-220
• /
• 2005

This paper presents and analyzes laboratory test results of Equalization Digital On-Channel Repeater (EDOCR) using ATSC(Advanced Television Systems Committee) terrestrial digital TV broadcasting system. The EDOCR laboratory test, which is done at CRC(Communications Research Centre) Canada, is classified to receiver test, transmitter test, and synchronization test between transmission and reception frequencies. The receiver part includes feedback signal, random noise, single echo, multi-path ensemble, and NTSC/DTV interference test. The transmitter part includes out-of channel emission, quality of transmitting signal, and phase noise test. By the field test results, the receiver part of the EDOCR eliminates average 5.5 dB of feedback or single echo signal in range of 0 to 11 ${\mu}s$ and has average 18.6 dB at TOV(Threshold of Visibility) under random noise environment. Also, the transmitter part of the EDOCR satisfies the specification of US FCC(Federal Communications Commission), and frequency difference between transmitter and receiver is zero.

• The Journal of the Convergence on Culture Technology
• /
• v.6 no.2
• /
• pp.437-447
• /
• 2020

The purpose of this study is to research the countermeasures and expected effects through the use of drones in the field of disaster prevention as a drone-based smart quarantine performance method. The environmental, market, and technological approaches to the review of the current quarantine performance task and its countermeasures are as follows. First, in terms of the environment, the effectiveness of the quarantine performance business using drone-based control is to broaden the utilization of forest, bird flu, livestock, facility areas, mosquito larvae, pests, and to simplify and provide various effective prevention systems such as AI and cholera. Second, in terms of market, the standardization of livestock and livestock quarantine laws and regulations according to the use of disinfection and quarantine missions using domestic standardized drones through the introduction of new technologies in the quarantine method, shared growth of related industries and discovery of new markets, and animal disease prevention It brings about the effect of annual budget savings. Third, the technical aspects are (1) on-site application of disinfection and prevention using multi-drone, a new form of animal disease prevention, (2) innovation in the drone industry software field, and (3) diversification of the industry with an integrated drone control / control system applicable to various markets. (4) Big data drone moving path 3D spatial information analysis precise drone traffic information ensures high flight safety, (5) Multiple drones can simultaneously auto-operate and fly, enabling low-cost, high-efficiency system deployment, (6) High precision that this was considered due to the increase in drone users by sector due to the necessity of airplane technology. This study was prepared based on literature surveys and expert opinions, and the future research field needs to prove its effectiveness based on empirical data on drone-based services. The expected effect of this study is to contribute to the active use of drones for disaster prevention work and to establish policies related to them.

• Journal of Navigation and Port Research
• /
• v.34 no.1
• /
• pp.15-19
• /
• 2010

Recently, the wireless LAN system is rapidly growing because of its convenience of high speed communication. However, the wireless LAN systems at indoor places occur multi-propagation path by reflected waves from walls, ceilings, floors, and desks. Multipath problems cause transmission errors and degradation of communication speed. These problems can be solved by using EM wave absorbers. In this paper, we analyzed property of Graphite and derived the optimum ratio of Graphite: CPE to develop EM wave absorber for the wireless LAN system. First, we fabricated several samples in different composition ratios of Graphite and CPE, and then measured the reflection coefficient of each samples. Material constants of permittivity and permeability were calculated using the measured data and designed EM wave absorber. Secondly, the EM wave absorber was fabricated and tested on the base of the simulation data. As a result, it showed that the EM wave absorber in 1.7 mm thickness with the ratio of Graphite: CPE=50:50 wt.% has excellent absorption ability more than 27 dB at 5.2 GHz.

• International Area Studies Review
• /
• v.14 no.1
• /
• pp.221-254
• /
• 2010

This study is for analyzing the mgmt performances of Korean tourism firms, operating as preparing strategically against FTA, one of the most importantly external environment in int'l mgmt since in the mid of 1990s. The main purpose can be mentioned to test empirically some relations between the mgmt performances of Korean tourism ones and the economic effects originated from FTA. The dependent variables of mgmt performances are classified with sales, profits and mgmt satisfaction, while the independent one regarding with economic effects from FTA are sorted based on the previous studies with the 2 following factors like direct with inbound/outbound and indirect effects. This study is conducted in two stages. Firstly, the research model is designed by the reviewing relevant theories and previous studies. Secondly, the survey of Korean tourism firms engaging in mgmt activities is implemented by collecting questionnaires. And for testing the hypothesis, the analyzing tools are used for correlation, reliability, validity and multi-regression on SPSS 12.0 and the path analysis of structural equation modeling is activated with AMOS 11.0.

• Journal of Global Scholars of Marketing Science
• /
• v.20 no.2
• /
• pp.123-134
• /
• 2010

Considering the benefits for both consumers and suppliers, firms are taking advantage of the Internet as a medium to communicate with and sell products to their consumers. This trend makes the online shopping environment a growing field for both researchers and practitioners. This paper contributes by testing a model of online consumer behavior with websites varying in levels of hedonism. Unlike past studies, we included all three types of emotions (arousal, pleasure, and dominance) and flow into the model. In this study, we assumed that website interfaces, such as background colors, music, and fonts impact the three types of emotions at the initial exposure to the site (Mazaheri, Richard, and Laroche, 2011). In turn, these emotions influence flow and consumers' perceptions of the site atmospherics-perception of site informativeness, effectiveness, and entertainment. This assumption is consistent with Zajonc (1980) who argued that affective reactions are independent of perceptual and cognitive operations and can influence responses. We, then, propose that the perceptions of site atmospherics along with flow, influence customers' attitudes toward the website and toward the product, site involvement, and purchase intentions. In addition, we studied the moderating impact of the level of hedonism of websites on all the relationship in the model. Thus, the path coefficients were compared between "high" and "low" hedonic websites. We used 39 real websites from 12 product categories (8 services and 4 physical goods) to test the model. Among them, 20 were perceived as high hedonic and 19 as low hedonic by the respondents. The result of EQS 6.1 support the overall model: $\chi^2$=1787 (df=504), CFI=.994; RMSEA=.031. All the hypotheses were significant. In addition, the results of multi-groups analyses reveal several non-invariant structural paths between high and low hedonic website groups. The findings supported the model regarding the influence of the three types of emotions on customers' perceptions of site atmospherics, flow, and other customer behavior variables. It was found that pleasure strongly influenced site attitudes and perceptions of site entertainment. Arousal positively impacted the other two types of emotions, perceptions of site informativeness, and site involvement. Additionally, the influence of arousal on flow was found to be highly significant. The results suggested a strong association between dominance and customers' perceptions of site effectiveness. Dominance was also found to be associated with site attitudes and flow. Moreover, the findings suggested that site involvement and attitudes toward the product are the most important antecedents of purchase intentions. Site informativeness and flow also significantly influenced purchase intentions. The results of multi-group analysis supported the moderating impacts of hedonism of the websites. Compared to low (high) hedonic sites, the impacts of utilitarian (hedonic) attributes on other variables were stronger in high (low) hedonic websites. Among the three types of emotions, dominance (controlling feelings) effects were stronger in high hedonic sites and pleasure effects were stronger in low hedonic sites. Moreover, the impact of site informativeness was stronger for high hedonic websites compared to their low-hedonic counterparts. On the other hand, the influence of effectiveness of information on perceptions of site informativeness and the impact of site involvement on product attitudes were stronger for low hedonic websites than for high hedonic ones.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.15 no.3
• /
• pp.191-206
• /
• 2020

Although several studies have been conducted on unification and the life of North Korean refugees, there have been few studies comparing the characteristics of North Korean refugees with South Korean workers, in terms of human resources in business administration. By considering the limitations of these prior studies, this study analyzed whether there are differences in factors affecting organizational commitment and turnover intention through a group comparative analysis between North Korean refugees and South Korean workers. For a comparative analysis between the two groups, we recruited 145 workers from North Korea and 213 South Korea-born workers. We found the following results with a multi-group structural equation model. We confirmed the measurement homogeneity by ensuring that both groups were equally aware of the measurement tools affecting organizational commitment and turnover intentions. As a result of testing the homogeneity of measurement, we also confirmed that there was a significant difference in optimism between the two groups; optimism affects organizational commitment and among social supports, affectionate support and interaction support affect organizational commitment. Analyzing the path between the two groups, we first were able to find that optimism influenced organizational commitment for both groups, in relation to positive psychological capital. However, in terms of degree, South Korean workers were found to be strongly affected. Second, with regard to social support, we were not able to find that affectionate support and interaction support have a significant impact on organizational commitment for South Korean workers, while for North Korean refugees, we confirmed that both supports have a significant impact. Third, we were unable to find any differences between the two group, in terms of other sub-components of positive psychological capital (self-efficacy, hope, and resiliency) or the sub-components of social support (informational support, tangible support). These results suggest that companies or managers employing North Korean refugee workers need to create an organizational environment that allows them to perceive social support, especially affectionate support and interaction support.