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A Study of 5G Systems to Improve Receiver Performance in the mmWave Band (밀리미터파 대역의 수신 성능을 개선하기 위한 5G 시스템에 대한 연구)

  • Myeong-saeng Kim;Dong-ok Kim
    • Journal of Advanced Navigation Technology
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    • v.28 no.3
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    • pp.362-368
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    • 2024
  • In this paper, we investigated the performance of directional and omnidirectional precoding schemes when transmitting to improve downlink performance in massive MIMO. Omnidirectional precoding was used to broadcast a common signal, such as a synchronization or control signal, to all users. The main purpose of omnidirectional precoding is to design the precoding matrix so that the signal transmitted in the downlink is the same in all directions and emitted with maximum energy. We propose a flexible omnidirectional precoding method for full-dimensional massive MIMO that can set the spatial coverage range to less than 120 degrees. The constraints of omnidirectionality of all antennas, equal transmit power, and maximum transmit rate are used to design the encoding matrix of the proposed method. The performance was evaluated in terms of spatial coverage by considering changing the spatial coverage of the antenna array by changing the distance between neighboring antennas in the antenna array.

A Study on Trade Structure between MERCOSUR and Korea (남미공동시장(MERCOSUR)과 한국의 교역구조에 관한 연구)

  • Chong-Suk Park
    • Asia-Pacific Journal of Business
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    • v.14 no.4
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    • pp.371-385
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    • 2023
  • Purpose - The purpose of this study is to analyze Korea's trade relations centered on the MERCOSUR, a major economic integration in Latin America, and identify its problems and suggest measures that can be taken by the government and corporations to reinforce economic cooperation. Design/methodology/approach - To improve the level of contribution of the study, an empirical analysis is necessary. However, due to limited data access, the study will approach the topic of trade relations between Korea and the MERCOSUR with various statistics and literature. Findings - First, there is an urgent need for changes in import-export goods between Korea and the MERCOSUR, as trade is focused on specific items. Second, although foreign direct investment from Korea to the MERCOSUR is centered in manufacturing and mining industries, there should be different investment strategies by countries and industries. Third, it is necessary to reinforce commercial cooperation. Korea currently has Free Trade Agreements with Chile, Peru, and Columbia, but not with MERCOSUR. Therefore, Korea must take active measures to sign an TA with MERCOSUR, which has been put on hold. Research implications or Originality - Latin America has the most thriving market when it comes to Free Trade Agreements worldwide. MERCOSUR is a South American Trade Bloc established by the Treaty of Asunción in 1991 and Protocol of Ouro Preto in 1994. Its full members are Brazil, Argentina, Uruguay and Paraguay. However, there is still a lack of research on the MERCOSUR, and corporations that aim to enter the Latin American market face difficulties due to lack of information. By investigating MERCOSUR and its prospects and analyzing the trade relations with Korea, this study will provide strategic measures for corporations that wish to enter the Latin American market.

A Study on the Job Burnout and Turnover Intention due to Work Overload: Focusing on IT workers (업무과부하에 따른 직무소진 및 이직의도에 관한 연구: IT 종사자들을 중심으로)

  • Jung-Min Lee;Min-Hee Hong
    • Advanced Industrial SCIence
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    • v.3 no.3
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    • pp.20-28
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    • 2024
  • This study aimed to verify the mediating effect of job burnout on the relationship between work overload and turnover intention among IT workers. For this study, a sample of 499 IT workers completed the online questionnaires: job demand scale, job burnout(emotional exhaustion, cynicism, professional efficacy) scale, turnover intention scale. The collected data were statistically analyzed using SPSS 25.0, and the Sobel test was conducted to verify the mediating effect. The results showed that work overload had a significant positive correlation with emotional exhaustion, cynicism, and turnover intention. Work overload had significant positive effects on emotional exhaustion and turnover intention. The full mediating effect of emotional exhaustion on the relationship between work overload and turnover intention was verified. Based on the findings, we discussed the necessity of addressing emotional exhaustion to prevent issues related to work overload and turnover intention among IT workers. Finally, we proposed human resource management strategies to address job burnout in IT workers and suggested directions for future research.

Long-term shape sensing of bridge girders using automated ROI extraction of LiDAR point clouds

  • Ganesh Kolappan Geetha;Sahyeon Lee;Junhwa Lee;Sung-Han Sim
    • Smart Structures and Systems
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    • v.33 no.6
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    • pp.399-414
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    • 2024
  • This study discusses the long-term deformation monitoring and shape sensing of bridge girder surfaces with an automated extraction scheme for point clouds in the Region Of Interest (ROI), invariant to the position of a Light Detection And Ranging system (LiDAR). Advanced smart construction necessitates continuous monitoring of the deformation and shape of bridge girders during the construction phase. An automated scheme is proposed for reconstructing geometric model of ROI in the presence of noisy non-stationary background. The proposed scheme involves (i) denoising irrelevant background point clouds using dimensions from the design model, (ii) extracting the outer boundaries of the bridge girder by transforming and processing the point cloud data in a two-dimensional image space, (iii) extracting topology of pre-defined targets using the modified Otsu method, (iv) registering the point clouds to a common reference frame or design coordinate using extracted predefined targets placed outside ROI, and (v) defining the bounding box in the point clouds using corresponding dimensional information of the bridge girder and abutments from the design model. The surface-fitted reconstructed geometric model in the ROI is superposed consistently over a long period to monitor bridge shape and derive deflection during the construction phase, which is highly correlated. The proposed scheme of combining 2D-3D with the design model overcomes the sensitivity of 3D point cloud registration to initial match, which often leads to a local extremum.

Analysis of Research Trends and Issues in Smart Tourism: A Comparative Study between South Korea and China (스마트관광 연구 동향 및 이슈 분석: 한국과 중국 비교연구)

  • Soo Jin Kim;Yang Gi Kim;Sang Jeong Moon
    • Smart Media Journal
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    • v.13 no.9
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    • pp.18-26
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    • 2024
  • The development of information and communication technology and advanced technologies has led to the full-fledged implementation of smart tourism in the tourism industry. Concurrently, both domestic and international research on smart tourism has been actively pursued. This study aimed to compare and analyze the trends and issues in smart tourism research between South Korea and China, to identify differences in issues related to smart tourism in both countries, and to suggest directions for future research in smart tourism. For this purpose, a text mining analysis was conducted on 69 Korean papers and 42 Chinese papers related to smart tourism published from January 2020 to June 2024. The analysis showed that Korean research on smart tourism focused heavily on improving the quality and satisfaction of tourists' experiences and understanding their behavioral intentions, while Chinese research emphasized provision of immersive contents and studies on sustainable tourism. Based on the analysis results, implications for smart tourism research were presented, along with limitations of this study and future research directions.

Expression of full and fragment-B of diphtheria toxin genes in Escherichia coli for generating of recombinant diphtheria vaccines

  • Shaimaa Abulmagd;Abd El-Nasser A. Khattab;Hamdallah Zedan
    • Clinical and Experimental Vaccine Research
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    • v.11 no.1
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    • pp.12-29
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    • 2022
  • Purpose: In the present study, whole diphtheria toxin (dt) and fragment B (dtb) genes from Corynebacterium diphtheriae Park William were cloned into Escherichia coli, the purified expressed proteins were evaluated for ultimately using as a candidate vaccine. Materials and Methods: The dt and dtb genes were isolated from bacterial strain ATCC (American Type Culture Collection) no. 13812. Plasmid pET29a+ was extracted by DNA-spin TM plasmid purification kit where genes were inserted using BamHI and HindIII-HF. Cloned pET29a+dt and pET29a+dtb plasmids were transformed into E. coli BL21(DE3)PlysS as expression host. The identity of the sequences was validated by blasting the sequence (BLASTn) against all the reported nucleotide sequences in the NCBI (National Center for Biotechnology Information) GenBank. Production of proteins in high yield by different types and parameters of fermentation to determine optimal conditions. Lastly, the purified concentrated rdtx and rdtb were injected to BALB/c mice and antibody titers were detected. Results: The genetic transformation of E. coli DH5α and E. coli BL21 with the pET-29a(+) carrying the dt and dtb genes was confirmed by colony polymerase chain reaction assay and were positive to grow on Luria-Bertani/kanamycin medium. The open reading frame of dt and dtb sequences consisted of 1,600 bp and 1,000 bp, were found to be 100% identical to dt and dtb sequence of C. diphtheriae (accession number KX702999.1 and KX702993.1) respectively. The optimal condition for high cell density is fed-batch fermentation production to express the rdtx and rdtb at 280 and 240 Lf/mL, dissolved oxygen was about 24% and 22% and the dry cell weight of bacteria was 2.41 g/L and 2.18 g/L, respectively. Conclusion: This study concluded with success in preparing genetically modified two strains for the production of a diphtheria vaccine, and to reach ideal production conditions to achieve the highest productivity.

Deep Learning-Based VOTE Classification and Full Occlusion Prediction in Drug-Induced Sleep Endoscopy (약물 유도 수면내시경에서 딥러닝을 이용한 VOTE 분류 및 완전폐쇄 예측)

  • Hyeon-Ji Yang;Seung-Jun Lee;Hyun-Seo Oh;Myungeun Lee;Hyung-Jeong Yang;Hyung-Chae Yang
    • Annual Conference of KIPS
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    • 2024.10a
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    • pp.692-695
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    • 2024
  • 폐쇄성 수면 무호흡증(Obstructive Sleep Apnea, OSA)은 수면 중 상기도의 폐쇄로 호흡 저하 및 중단이 발생하는 질환이다. 약물 유도 수면내시경(Drug-induced sleep endoscopy, DISE)은 이러한 상기도의 폐쇄 위치를 파악하는 데 사용되며, VOTE(Velum, Oropharynx, Tongue base, Epiglottis) scoring을 통해 DISE 결과를 판독한다. 하지만 VOTE scoring은 의료진이 주관적으로 각 해부학적 위치의 폐쇄 정도를 판단하기 때문에, 의료진의 해석에 따라 진단 결과가 달라질 수 있으며, 이로 인한 판독자간 판독 불일치가 상당하다. 따라서 본 연구는 딥러닝 모델을 활용하여 DISE 영상에서 VOTE 영역을 자동으로 분류하고 상기도의 완전폐쇄 여부를 예측하고자 한다. 연구개(V), 연구개 완전폐쇄(V degree 2), 구인두-혀 기저부-후두덮개(OTE), 구인두-혀 기저부-후두덮개 완전폐쇄(OTE degree 2), 왜곡(X) 총 5가지 클래스로 분류하였다. 이러한 분류 체계는 상기도의 부위별 폐쇄를 더 정확하고 체계적으로 예측할 수 있게 해 준다. 이를위해 13명의 환자로부터 수집된 DISE 영상 데이터셋과 임상 정보를 기반으로 ResNet, DenseNet, VGG, EfficientNet과 같은 딥러닝 모델을 구현하고 성능을 비교했다. 그 결과 EfficientNet 모델이 80%의 정확도로 가장 뛰어난 성능을 보였다. 향후 연구에서는 DISE 영상에서 상기도 폐쇄 양상을 더욱 세분화하여 분석하고자 한다.

Validation Study for Image Performance of I-131 Using GATE Simulation Program (GATE 시뮬레이션 프로그램을 이용한 I-131의 영상 특성의 타당성에 관한 연구)

  • Baek, Cheol-Ha;Kim, Dae Ho;Lee, Yong-Gu;Lee, Youngjin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.5
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    • pp.133-137
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    • 2017
  • The purpose of this study was to validate for GATE (Geant4 Application for Tomographic Emission) simulation by comparing the results of GATE simulation and experiment in real SPECT system. Futhermore, we want to prove that it is possible that the quantitative research of gamma camera/SPECT imaging for therapeutic radio isotope by using GATE simulation. In this study, the SPECT system on simulation referred to the parameters of Stream-R Forte version 1.2 (Philips Medical System, Best and Heerlen, Netherlands). To understand the I-131 image of gamma camera/SPECT system, we acquired the energy spectrum and measured the full width at half maximum (FWHM) which comes from line spread function (LSF) with and without scatter material in real SPECT system. And to compare with experiment, we also measured the FWHM and acquired the energy spectrum without scatter material in GATE simulation. As a result, without scatter material, the energy peak was almost same location, which are located nearby 364 keV, and other spectrum factors are same tendency in both cases. The FWHM was increased by increasing the distance of source to detector, and the error rate was approximately 3.8%. When we used the line source with scatter material, energy spectrum also indicated similar tendency in both cases. As you confirmed earlier, GATE simulation included real instrument and radioisotope characters for therapeutic radioisotope. Therefore this result that it was possible that various quantitative study for therapeutic radioisotope imaging in gamma camera/SPECT using GATE simulation.

The Effect of the Participative Leadership on Creative Behavior - Focusing on Unidimensional and Multidimensional Mediating Effects of Psychological Empowerment - (참여적 리더십이 창의적 행동에 미치는 영향 - 심리적 임파워먼트의 단일차원과 다차원 매개효과를 중심으로 -)

  • Tak, Je-Woon;Shin, Je-Goo
    • Management & Information Systems Review
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    • v.36 no.5
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    • pp.61-83
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    • 2017
  • The purpose of this study is to investigate the mediating effects of psychological empowerment between participative leadership and creative behavior. Especially, it aims to analyze the unidimension and multidimension of psychological empowerment in an integrated manner, and to suggest effective practice of participative leadership together with theoretical and methodological implications. In this study, the dependent variable was measured separately with time lag as a method to solve the common method bias that can be shown by the self-report type survey method, and positive emotions and negative emotions expressing emotional states in job situations were employed as control variables along with rank. A total of 283 questionnaires were collected from employees who work for companies in various industries with more than 300 domestic employees. SPSS PROCESS macro program('model 4') was used for statistical analysis. Results, First, the full mediation effect of psychological empowerment(unidimension) was confirmed in the relationship between participative leadership and creative behavior. Second, the analysis of the multidimension of psychological empowerment revealed the full mediating effect of meaning, self-determination, and impact, and the mediating effect of competence was not significant. Third, as a result of comparing the mediating effects of unidimension of psychological empowerment and the mediating effects of multidimension, the magnitude of mediating effect of unidimension was found to be much greater than mediating effect of multidimension. And The magnitudes of the three multidimensional mediating effects were similar. This is a case in which the motivational model of participative leadership revealed in the overseas study is proven in the domestic management environment and is significant in that it is the basis of future research. Based on the results of the empirical studies, the implications and limitations of the study and future research directions are presented.

A Study on Industries's Leading at the Stock Market in Korea - Gradual Diffusion of Information and Cross-Asset Return Predictability- (산업의 주식시장 선행성에 관한 실증분석 - 자산간 수익률 예측 가능성 -)

  • Kim Jong-Kwon
    • Proceedings of the Safety Management and Science Conference
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    • 2004.11a
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    • pp.355-380
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    • 2004
  • I test the hypothesis that the gradual diffusion of information across asset markets leads to cross-asset return predictability in Korea. Using thirty-six industry portfolios and the broad market index as our test assets, I establish several key results. First, a number of industries such as semiconductor, electronics, metal, and petroleum lead the stock market by up to one month. In contrast, the market, which is widely followed, only leads a few industries. Importantly, an industry's ability to lead the market is correlated with its propensity to forecast various indicators of economic activity such as industrial production growth. Consistent with our hypothesis, these findings indicate that the market reacts with a delay to information in industry returns about its fundamentals because information diffuses only gradually across asset markets. Traditional theories of asset pricing assume that investors have unlimited information-processing capacity. However, this assumption does not hold for many traders, even the most sophisticated ones. Many economists recognize that investors are better characterized as being only boundedly rational(see Shiller(2000), Sims(2201)). Even from casual observation, few traders can pay attention to all sources of information much less understand their impact on the prices of assets that they trade. Indeed, a large literature in psychology documents the extent to which even attention is a precious cognitive resource(see, eg., Kahneman(1973), Nisbett and Ross(1980), Fiske and Taylor(1991)). A number of papers have explored the implications of limited information- processing capacity for asset prices. I will review this literature in Section II. For instance, Merton(1987) develops a static model of multiple stocks in which investors only have information about a limited number of stocks and only trade those that they have information about. Related models of limited market participation include brennan(1975) and Allen and Gale(1994). As a result, stocks that are less recognized by investors have a smaller investor base(neglected stocks) and trade at a greater discount because of limited risk sharing. More recently, Hong and Stein(1999) develop a dynamic model of a single asset in which information gradually diffuses across the investment public and investors are unable to perform the rational expectations trick of extracting information from prices. Hong and Stein(1999). My hypothesis is that the gradual diffusion of information across asset markets leads to cross-asset return predictability. This hypothesis relies on two key assumptions. The first is that valuable information that originates in one asset reaches investors in other markets only with a lag, i.e. news travels slowly across markets. The second assumption is that because of limited information-processing capacity, many (though not necessarily all) investors may not pay attention or be able to extract the information from the asset prices of markets that they do not participate in. These two assumptions taken together leads to cross-asset return predictability. My hypothesis would appear to be a very plausible one for a few reasons. To begin with, as pointed out by Merton(1987) and the subsequent literature on segmented markets and limited market participation, few investors trade all assets. Put another way, limited participation is a pervasive feature of financial markets. Indeed, even among equity money managers, there is specialization along industries such as sector or market timing funds. Some reasons for this limited market participation include tax, regulatory or liquidity constraints. More plausibly, investors have to specialize because they have their hands full trying to understand the markets that they do participate in

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