• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.43-49
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• 2006

The surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value, hard-to-remove water content, freezing and non-freezing bound water content, polymer adsorption, and crystallinity index. For a high-dosage enzyme treatment (0.10 g/g), the fiber length was significantly decreased and the fibers were 'cut' in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high-dosage treatment. Three independent measurements (non-freezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions. Based on the experimental results obtained herein, a model was proposed to explain surface and pore structure modification of cellulose fibers via enzymatic treatment.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.1-8
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• 2016

Optical particle sizer (OPS), optical particle counter (OPC), and aethalomter were deployed to measure the particle number concentrations from 0.3 to $10.0{\mu}m$ and black carbon (BC) concentrations. Comparisons of particle number concentrations measured by OPS and OPC were conducted to evaluate the performance of the each optical instrument at the Gwangju sampling site ($35.23^{\circ}N$, $126.84^{\circ}E$) for 14 days from Dec. 27 in 2014. Although a good correlation ($r^2=0.99$) between the OPS and OPC was observed for both the particle number and volume concentrations, different relationships by BC concentrations can be associated with the intensities by different light scattering angles. In addition, based on diurnal patterns of size distributions in 24 hr running correlation coefficient determination, BC concentrations were highly related to the particles less than $0.3{\mu}m$ observed in the morning traffic hour.

• Journal of Biosystems Engineering
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• v.22 no.2
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• pp.137-150
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• 1997

To investigate the feasibility of a boom sprayer in the paddy field, an experimental boom sprayer for both broadcast and directed spraying to the lower part of rice plants was developed. The droplet deposition characteristics of the boom sprayers were experimentally compared to those of power sprayer. Water sensitive papers(WSP) and a machine vision system were used to evaluate the coverage rate and droplet density. It was shown that the broadcast application by the boom sprayer was the best coverage among the tested sprayers. Coverage tate and droplet density were affected by the distance between nozzles and the sprayer ground speed, The best result was obtained when the distance of 30cm and the speed of 1.7km/hr. The directed application showed inconsistency in overall droplet distribution. The inconsistency was judged to be caused by conflict between plants and boom extenders. The power sprayer showed a very wide range of droplet size distribution, relatively larger droplets and inconsistency in cove The power sprayer was judged to be inadequate for the low-volume precision application because of inconsistency in performance and difficulty in adjusting the spraying rate. Based on the droplet coverage characteristics, it was concluded that the self-propelled boom sprayer for the broadcast application was feasible for an alternative to the power sprayer in case of low volume, precision application in paddy condition.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2909-2912
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• 2010

Hydrogenated microcrystalline silicon (${\mu}c$-Si:H) thin film for solar cells is prepared by plasma-enhanced chemical vapor deposition and physical properties of the ${\mu}c$-Si:H p-layer has been investigated. With respect to stable efficiency, this film is expected to surpass the performance of conventional amorphous silicon based solar cells and very soon be a close competitor to other thin film photovoltaic materials. Silicon in various structural forms has a direct effect on the efficiency of solar cell devices with different electron mobility and photon conversion. A Raman microscope is adopted to study the degree of crystallinity of Si film by analyzing the integrated intensity peaks at 480, 510 and $520\;cm^{-1}$, which corresponds to the amorphous phase (a-Si:H), microcrystalline (${\mu}c$-Si:H) and large crystals (c-Si), respectively. The crystal volume fraction is calculated from the ratio of the crystalline and the amorphous phase. The results are compared with high-resolution transmission electron microscopy (HR-TEM) for the determination of crystallinity factor. Optical properties such as refractive index, extinction coefficient, and band gap are studied with reflectance spectra.

• Journal of Radiation Protection and Research
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• v.34 no.4
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• pp.165-169
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• 2009

Two dosimeters are provided to radiation workers participating in tasks where high radiation exposure is expected during maintenance at nuclear power plants. At Korean nuclear power plants, two dosimeters are currently provided for tasks where exposure rates exceed 1 mSv/hr, the difference of equivalent dose to specific parts of the body is more than 30% and an exposure of more than 2 mSv is expected in a single task. These conditions for the provisioning of two dosimeters are based on previous field test results, and it is recommended that the dosimeters be worn on the chest and back. It was also found that the workers felt it was more convenient when they wore two dosimeters on chest and back rather than on chest and head. After the application of previous field test results to practice, it was found that the calculated effective dose for workers during radiation work was lower than the maximum dose of chest or back dosimeter by approximately 10%-30%. This performance is regarded not only to meet the international guideline but also to provide convenience for workers during radiation work.

• Journal of Wetlands Research
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• v.21 no.4
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• pp.384-391
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• 2019

Nutrients in stormwater runoff have raised concerns regarding water quality degradation in the recent years. Low impact development (LID) technologies are types of nature-based solutions developed to address water quality problems and restore the predevelopment hydrology of a catchment area. Two LID facilities, infiltration trench (IT) and infiltration planter (IP), are known for their high removal rate of nutrients through sedimentation and vegetation. Long-term monitoring was conducted to assess the performance and cite the advantages and disadvantages of utilizing the facilities in nutrient removal. Since a strong ionic bond exists between phosphorus compounds and sediments, reduction of total phosphorus (TP) (more than 76%), in both facilities was associated to the removal of total suspended solids (TSS) (more than 84%). The efficiency of nitrogen in IP is 28% higher than IT. Effective nitrification occurred in IT and particulate forms of nitrogen were removed through sedimentation and media filters. Decrease in ammonium- nitrogen (NH₄-N) and nitrite-nitrogen (NO₂-N), and increase in nitrate-nitrogen (NO₃-N) fraction forms indicated that effective nitrification and denitrification occurred in IP. Hydrologic factors such as rainfall depth and rainfall intensity affected nutrient treatment capabilities of urban stormwater LID facilities The greatest monitored rainfall intensity of 11 mm/hr for IT yielded to 34% and 55% removal efficiencies for TN and TP, respectively, whereas, low rainfall intensities below 5 mm resulted to 100 % removal efficiency. The greatest monitored rainfall intensity for IP was 27 mm/hr, which still resulted to high removal efficiencies of 98% and 97% for TN and TP, respectively. Water quality assessment showed that both facilities were effective in reducing the amount of nutrients; however, IP was found to be more efficient than IT due to its additional provisions for plant uptake and larger storage volume.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.159-170
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• 2021

As the main purpose of R&D changes from the center of knowledge creation to the center of economic value creation through technology transfer and commercialization, public technologies can also secure economic feasibility as well as make a social contribution. Korea has been focusing on fostering core human resources who can lead the commercialization of basic and original research results by launching the 'Support project for exploring startups linked with public technology-based markets' since 2015 in order to promote public technology startup. This study is based on the results of a survey for the purpose of analyzing the performance of this project. In addition, this study derived four factors related to the I-corps project performance from the results of this survey and verified the relationship between these factors through structural equation model analysis. In summary, it was confirmed that 'Application Level' and 'Business Model,' which are positively affected directly from 'Entrepreneurship Learning,' have positive effects on 'Financial Resources'. Furthermore, the indirect effect of 'Entrepreneurship Learning' on 'Financial Resources' was verified. In particular, the high level of impact of 'Entrepreneurship Learning' on 'Application Level,' and the impact of 'Application Level' on 'Business Model' and 'Financial Resources' were also positive.

• Science of Emotion and Sensibility
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• v.21 no.1
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• pp.177-186
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• 2018

The mechanism of emotion is complex and influenced by a variety of factors, so that it is crucial to analyze emotion in broad and diversified perspectives. In this study, we classified neutral and negative emotions(sadness, fear, surprise) using arousal evaluation, which is one of the psychological evaluation scales, as well as physiological signals. We have not only revealed the difference between physiological signals coupled to the emotions, but also assessed how accurate these emotions can be classified by our emotional recognizer based on neural network algorithm. A total of 146 participants(mean age $20.1{\pm}4.0$, male 41%) were emotionally stimulated while their physiological signals of the electrocardiogram, blood flow, and dermal activity were recorded. In addition, the participants evaluated their psychological states on the emotional rating scale in response to the emotional stimuli. Heart rate(HR), standard deviation(SDNN), blood flow(BVP), pulse wave transmission time(PTT), skin conduction level(SCL) and skin conduction response(SCR) were calculated before and after the emotional stimulation. As a result, the difference between physiological responses was verified corresponding to the emotions, and the highest emotion classification performance of 86.9% was obtained using the combined analysis of arousal and physiological features. This study suggests that negative emotion can be categorized by psychological and physiological evaluation along with the application of machine learning algorithm, which can contribute to the science and technology of detecting human emotion.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.4
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• pp.319-345
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• 2011

In case of tunnels in cold regions, a freeze of groundwater around tunnel may act as a barrier of tunnel drainage in winter, or may cause the inner extrusion of lining. In spite of that, a design of insulation for preventing the frost damage of tunnel lining has not been introduced in Korea, while foreign countries such as Norway and so on have a standard on insulation. In this study, a few freezing cases of road tunnels have been reviewed, and the results show that the freezing protection is necessary. In order to characterize the thermal distribution in the tunnel, following measurements have been performed at Hwa-ak tunnel; the temperature distribution by longitudinal lengths, the internal temperature of lining and the temperature distribution of the ground under pavement. From these measurements, the characteristics of the tunnel's internal temperature distribution due to temperature change in the air has been analyzed. Based on the measurement results on the temperature distribution at Hwa-ak tunnel, thermal flow tests on the rock specimen with and without insulation have been performed in the artificial climate chamber to investigate the performance of the insulation. Also, a number of 3D numerical analyses have been performed to propose appropriate insulation and insulation thicknesses for different conditions, which could prevent the frost damage of tunnel lining. As a result of the numerical analysis, air freezing index of 291$^{\circ}C{\cdot}$ Hr has been suggested as the threshold value for freezing criteria of groundwater behind the tunnel lining.

• Knowledge Management Research
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• v.25 no.2
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• pp.19-47
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• 2024

Organizational ability to analyze and utilize data plays an important role in knowledge management and decision-making. This study aims to investigate the potential application of large language models in corporate data analysis. Focusing on the field of human resources, the research examines the data analysis capabilities of these models. Using the widely studied IBM HR dataset, the study reproduces machine learning-based employee turnover prediction analyses from previous research through ChatGPT and compares its predictive performance. Unlike past research methods that required advanced programming skills, ChatGPT-based machine learning data analysis, conducted through the analyst's natural language requests, offers the advantages of being much easier and faster. Moreover, its prediction accuracy was found to be competitive compared to previous studies. This suggests that large language models could serve as effective and practical alternatives in the field of corporate data analysis, which has traditionally demanded advanced programming capabilities. Furthermore, this approach is expected to contribute to the popularization of data analysis and the spread of data-driven decision-making (DDDM). The prompts used during the data analysis process and the program code generated by ChatGPT are also included in the appendix for verification, providing a foundation for future data analysis research using large language models.