• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.97-101
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• 1991

Gas-phase pyrolyses of carbonate esters, ${\alpha}$- and ${\beta}$-hydroxy esters and ${\beta}$-hydroxy ketones have been studied theoretically by the AM1 MO method. Carbonate esters were found to decompose by two types of processes; in the reaction pathway involving an intermediate, the decomposition of the intermediate was rate-limiting, but direct pyrolyses were also possible via a six-membered cyclic transition state in which the methoxy oxygen attacks a hydrogen atom on the ${\beta}$-carbon. The hydroxy esters and ketones were found to decompose in a concerted process involving a six-membered cyclic transition state. Successive methylation on the ${\alpha}$- and ${\gamma}$-carbon led to an increase in the reactivity in agreement with experiments.

• Structural Engineering and Mechanics
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• v.71 no.5
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• pp.503-513
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• 2019

Genetic Algorithms (GAs) have found the best design for reinforced concrete frames. The design of the optimum beam sections by GAs has been unified. The process of the optimum-design sections has satisfied axial, flexural, shear and torsion necessities based on the designing code. The frames' function has contained the function of both concrete and reinforced steel besides the function of the frames' formwork. The results have revealed that limiting the dimension of frame-beam with the dimension of frame-column have increased the optimum function of the structure, thereby reducing the reanalysis requirement for checking the optimum-designed structures through GAs.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.2
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• pp.16-26
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• 2020

Improving operator performance in complex and time-critical situations is critical to maintain plant safety and operability. These situations require quick detection, diagnosis, and mitigation actions to recover from the root cause of failure. One of the key challenges for operators in nuclear power plants is information management and following the control procedures and instructions. Nowadays Digital Twin technology can be used for analyzing and fast detection of failures and transient situations with the recommender system to provide the operator or maintenance engineer with recommended action to be carried out. Systems engineering approach (SE) is used in developing a digital twin for the CEDM system to support operator actions when there is a misalignment in the control element assembly group. Systems engineering is introduced for identifying the requirements, operational concept, and associated verification and validation steps required in the development process. The system developed by using a machine learning algorithm with a text mining technique to extract the required actions from limiting conditions for operations (LCO) or procedures that represent certain tasks.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.31-31
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• 2022

Rice contains a wealth of genetic diversity, both within Oryza sativa and in related A-genome species. Decades of genetic research into this diversity have identified dozens of major genes contributing to a wide variety of important traits, including disease resistance, abiotic stress tolerance (drought, salinity, submergence, heat, cold etc.), grain quality, flowering date and maturity and plant architecture. Yet despite these opportunities, very few of the major genes and QTLs known have been successfully applied through rice breeding programs to produce sustained changes in farmer's fields. This presentation will briefly examine some of the factors limiting application of major genes in the mainstream breeding programs, and steps that have been taken to alleviate those limitations. As a result of these interventions, dozens of major genes that were previously unavailable to breeders are now being used confidently in the variety development process. Case studies will be discussed of genes critical for blast resistance worldwide, rice yellow mottle virus for Africa, and new validated QTLs for salinity tolerance.

• Membrane and Water Treatment
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• v.9 no.5
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• pp.373-383
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• 2018

Fouling by solids and microorganisms is the major obstacle limiting the efficient use of membrane wastewater treatment. In our previous study, two stages microalgae/membrane filtration system was proposed to treat anaerobic digested palm oil mill effluent (AnPOME). This two stages microalgae/membrane filtration system had showed great potential for the treatment of AnPOME with high removal of COD, $NH_3-N$, $PO_4{^{3-}}$, TSS, turbidity, and colour. However, fouling behavior of the membrane in this two stages microalgae/membrane filtration system was still unknown. In this study, empirical models that describe permeate flux decline for dead-end filtration (pore blocking - complete, intermediate, and standard; and cake layer formation) presented by Hermia were used to fit the experimental results in identifying the fouling mechanism under different experimental conditions. Both centrifuged and non-centrifuged samples were taken from the medium with 3 days RT intervals, from day 0 to day 12 to study their influence on fouling mechanisms described by Hermia for ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) filtration mode. Besides, a more detailed study on the use of resistance-in-series model for deadend filtration was done to investigate the fouling mechanisms involved in membrane filtration of AnPOME collected after microalgae treatment. The results showed that fouling of UF and NF membrane was mainly caused by cake layer formation and it was also supported by the analysis for resistance-in-series model. Whereas, fouling of RO membrane was dominated by concentration polarization.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.2
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• pp.37-42
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• 2008

Defects of corrugated board were limiting factors to the corrugated industry's growth. On-line detecting systems of defects are beneficial to increase profits of the corrugated board companies by reducing base paper consumption, increasing process reliability, and increasing productivity. By replacing naked eye inspection of defects to a defects detecting system, continuous inspection without fatigue may guarantee final products quality. The system was developed, which was consisted of line scan CCD camera, lens, illuminating parts, high speed image processor, software, various input parts, and output parts. First installation location of the system was at before fluting process after base paper unwinding, and surface of liner board was inspected by the system. Second installation location was after fluting process and combining process for liner board. Production loss includes ragged appearance of edge, irregular flute shape, wrong combination of flute, score cracking, defects in base paper, and flute cracking. The production loss was analyzed before and after the system installation at a commercial domestic mill. The production loss ratio was defined as a production loss weight per total production weight. The production loss ratio before the installation was decreased a lot from 1.28%(during 3 months before installation) to 0.76%(during 12 months after the first installation) and to 0.25%(during 6 months after the second installation).

• Composites Research
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• v.31 no.1
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• pp.23-29
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• 2018

The RFI process can be applied to very thick structures without limiting the resin viscosity. When the proper thickness of the resin film cannot be set, the resin film creates either the non-impregnated section or the excessive resin contents and this leads to the deterioration of mechanical properties. Therefore, this study proposed a method for setting the resin film thickness in the RFI process. The fiber compaction behavior test was proposed by setting the proper resin film thickness and the properties of composites were evaluated through short beam shear strength test, compression test and porosity measurement to verify the proposed method. The evaluation of physical properties of composites was conducted and an appropriate level of resin film thickness was found based on the results of fiber compaction behavior test.

• Korean Journal of Legislative Studies
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• v.24 no.1
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• pp.31-66
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• 2018

The purpose of this study is to analyze the institutional factors and the political environment in which the influence of the president is limited in South Korea's decision making process of the policy toward North Korea. Although the president has the highest decision-making power over policy toward North Korea as a head of state, the president's influence is not always absolute. Many reasons, such as bureaucratic government through the separation of power, the political environment such as divided government or the remaining term of the president,and the specificity of policy act as factors limiting the president's influence on policy toward North Korea. This study analyzed the dynamics of the decision making process of the 'Special Zone for Peace and Cooperation in the West Sea' which was planned by the agreement between the two Koreas in 2007, and examined the influence of the president, limited by the institutional environment and political conditions in the process.

• Journal of Information Technology Services
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• v.20 no.2
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• pp.57-76
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• 2021

Today's ERP system has become a core system of IT·SW that not only supports and manages enterprise resources efficiently, but also encompasses major business tasks. In other words, the ERP system is an essential strategic element for the survival of a company as a powerful means to innovate the management of an organization. This study analyzed the impact on the utilization of IT·SW from the perspective of the entire organization's process without limiting the performance evaluation of the ERP system itself, which is a core system of a company. The measurement data for evaluating the performance of the ERP system was the 2018 domestic company IT·SW utilization survey result report (subject to survey : 3,017 domestic companies with 10 or more employees). Based on this data, this study analyzed the impact of the ERP system on the entire enterprise's IT·SW utilization. In particular, attention was paid to whether there would be a difference in the use of IT·SW if the type of ERP system introduction was changed through the improvement of the business process of the company. Multiple regression analysis was performed using the statistical package SPSS 25. As a result, among the ERP system introduction types, the greatest degree of (+)influence on the company's IT·SW utilization is when the ERP package SW or ASP service is used as it is. Although the difference is insignificant, the second case was to build an ERP system through self-development or outsourcing, followed by customizing the package SW or system through self-development or outsourcing. Through the results of this study, it is expected that the organization will improve the business process and use the standard ERP package SW as it is without modification, thereby effectively enhancing the use of IT·SW of the company and leading to management performance.

• The Korean Journal of Applied Statistics
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• v.29 no.2
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• pp.301-308
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• 2016

The process capability index is used to determine whether a production process is capable of producing items within a specified tolerance. Some process capability indices $C_p$, $C_{pk}$ and $C_{pm}$ have been of particular interest as useful management tools for tracking process performance. Most evaluations on process capability indices focus on statistical estimation and test of hypothesis. It is necessary to investigate their asymptotic correlationship among basic estimators ${\hat{C}}_p$, ${\hat{C}}_{pk}$ and ${\hat{C}}_{pm}$ of process capability indices $C_p$, $C_{pk}$ and $C_{pm}$. In this paper, we study their asymptotic correlationship for three process capability indices ${\hat{C}}_p$, ${\hat{C}}_{pk}$ and ${\hat{C}}_{pm}$ under bivariate normal distribution BN(${\mu}_x,{\mu}_y,{\sigma}^2_x,{\sigma}^2_y,{\rho}$). With some nonnormal processes, the asymptotic correlation coefficient of any two respective process capability index estimators could be established.