• The Journal of the Korea Contents Association
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• v.19 no.6
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• pp.347-358
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• 2019

This study used Q methodology for analogizing culinary arts major students' subjectivity through their participation of one of restaurant start-up experience program, called pop-up restaurant. The study tried to figure out particular structure of among students' responses and noticed five distinctive types. There were Increase learning effect type(Type 1, N=4), Collaboration of members importance type(Type2, N=8), Marketing PR need type(Type3, N=6), Restaurant business plan type(Type4, N=4), Industry work experience required type(Type5, N=3). The study also revealed that each type contained diverse characteristics figures in their own. The research finding could be used as fundamental source of future similar research but in other research methodology in the format of difference among students or diverse measuring point of time frame.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.2
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• pp.133-142
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• 2023

The large process plant is currently implementing predictive maintenance technology to transition from the traditional Time-Based Maintenance (TBM) approach to the Condition-Based Maintenance (CBM) approach in order to improve equipment maintenance and productivity. The traditional techniques for predictive maintenance involved managing upper/lower thresholds (Set-Point) of equipment signals or identifying anomalies through control charts. Recently, with the development of techniques for big analysis, machine learning-based AAKR (Auto-Associative Kernel Regression) and deep learning-based VAE (Variation Auto-Encoder) techniques are being actively applied for predictive maintenance. However, this predictive maintenance techniques is only effective during steady-state operation of plant equipment, and it is difficult to apply them during start-up and shutdown periods when rises or falls. In addition, unlike processes such as nuclear and thermal power plants, which operate for hundreds of days after a single start-up, because the pumped power plant involves repeated start-ups and shutdowns 4-5 times a day, it is needed the prediction and alarm algorithm suitable for its characteristics. In this study, we aim to propose an approach to apply the optimal predictive alarm algorithm that is suitable for the characteristics of Pumped Storage Power Plant(PSPP) facilities to the system by analyzing the predictive maintenance techniques used in existing nuclear and coal power plants.

• Asia-Pacific Journal of Business
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• v.14 no.3
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• pp.241-250
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• 2023

Purpose - The purpose of this study was to investigate the perception of 'unmanned cafes' on the network through big data analysis, and to identify the latest trends in rapidly changing consumer perception. Based on this, I would like to suggest that it can be used as basic data for the revitalization of unmanned cafes and differentiated marketing strategies. Design/methodology/approach - This study collected documents containing unmanned cafe keywords for about three years, and the data collected using text mining techniques were analyzed using methods such as keyword frequency analysis, centrality analysis, and keyword network analysis. Findings - First, the top 10 words with a high frequency of appearance were identified in the order of unmanned cafes, unmanned cafes, start-up, operation, coffee, time, coffee machine, franchise, and robot cafes. Second, visualization of the semantic network confirmed that the key keyword "unmanned cafe" was at the center of the keyword cluster. Research implications or Originality - Using big data to collect and analyze keywords with high web visibility, we tried to identify new issues or trends in unmanned cafe recognition, which consists of keywords related to start-ups, mainly deals with topics related to start-ups when unmanned cafes are mentioned on the network.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.1
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• pp.29-43
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• 2022

This study measures the realized rate of return of venture capital(VC) fund at the level of investment agreement(as opposed to fund level returns reported by most of the relevant studies). It also measures the stock price return of the VC's portfolio firms (unlisted start-ups) at firm level(as opposed to fund returns) and its variance for the first time using unique data of the VC funds held by the Korean Venture Capital Association. Results of the analysis confirm that VC fund returns exceed individual stock price returns. Additionally, it is confirmed that VC portfolio firms exhibit a positive relationship between risk and return measured by total risk. Finally, we find that stock price returns at firm level are lower than that implied by the associated levels of risk. Consequently, this may make individual investors hesitate to directly buy unlisted startups' stocks even when investment in individual startup companies guarantees high risk-high returns relationship.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.157-165
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• 2004

Real-time(RT) object-oriented(OO) distributed computing is a form of RT distributed computing realized with a distributed computer system structured in the form of an object network. Several approached proposed in recent years for extending the conventional object structuring scheme to suit RT applications, are briefly reviewed. Then the approach named the TMO(Time-triggered Message-triggered Object)structuring scheme was formulated with the goal of instigating a quantum productivity jump in the design of distributed time triggered simulation. The TMO scheme is intended to facilitate the pursuit of a new paradigm in designing distributed time triggered simulation which is to realize real-time computing with a common and general design style that does not alienate the main-stream computing industry and yet to allow system engineers to confidently produce certifiable distributed time triggered simulation for safety-critical applications. The TMO structuring scheme is a syntactically simple but semantically powerful extension of the conventional object structuring approached and as such, its support tools can be based on various well-established OO programming languages such as C++ and on ubiquitous commercial RT operating system kernels. The Scheme enables a great reduction of the designers efforts in guaranteeing timely service capabilities of application systems. Start after striking space key 2 times.

• Korean Journal of Computational Design and Engineering
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• v.8 no.4
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• pp.254-261
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• 2003

In mold and die shops, NC machining process mainly affects the quality of the machined surface and the manufacturing time of molds and dies. The estimation of NC machining time is a prerequisite to measure the machining productivity and to generate a process schedule, which generally includes the process sequence and the completion time of each process. It is required to take into account dynamic characteristics in the estimation, such as the ac/deceleration of NC machine controllers. Intensive observations at start and end points of NC blocks show that a minimum feedrate, a key variable in a machining time model, has a close relation to a block distance, an angle between blocks, and a command feedrate. Thus, this study addresses regression models for the minimum feedrate estimation on short and long NC blocks considering these parameters. Furthermore, machining time estimation models by the four types of feedrate behaviors are suggested based on the estimated minimum feedrate. To show the validity of the proposed machining time model, the study compares the estimated with the actual machining time in the sculptured surface machining of several mold dies.

• Journal of Computational Design and Engineering
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• v.3 no.2
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• pp.132-139
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• 2016

In this paper, a minimum time path planning strategy is proposed for multi points manufacturing problems in drilling/spot welding tasks. By optimizing the travelling schedule of the set points and the detailed transfer path between points, the minimum time manufacturing task is realized under fully utilizing the dynamic performance of robotic manipulator. According to the start-stop movement in drilling/spot welding task, the path planning problem can be converted into a traveling salesman problem (TSP) and a series of point to point minimum time transfer path planning problems. Cubic Hermite interpolation polynomial is used to parameterize the transfer path and then the path parameters are optimized to obtain minimum point to point transfer time. A new TSP with minimum time index is constructed by using point-point transfer time as the TSP parameter. The classical genetic algorithm (GA) is applied to obtain the optimal travelling schedule. Several minimum time drilling tasks of a 3-DOF robotic manipulator are used as examples to demonstrate the effectiveness of the proposed approach.

• Design & Manufacturing
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• v.15 no.3
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• pp.45-49
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• 2021

In this study, during the injection molding process, a device was manufactured and evaluated that calculates a cooling time by measuring a vibration signal generated from a mold using an acceleration. The last two parts, one of which has a large magnitude change in the measured vibration signal of a mold, were divided into a cooling start section (paking end section) and a mold opening section, and the time difference at the relevant points was calculated as the cooling time. The cooling time was monitored on a 5-inch light guide plate mold by applying the method. The manufactured device was attached to a fixed base of mold to measure the cooling time, and data was obtained remotely using Bluetooth technology. Then, the measured cooling time was compared with the cooling time set in the injection molding machine to evaluate the accuracy. As a result of the experiment, the cooling times measured by the devices were 15.675±0.024 sec, 20.637±0.014 sec and 25.623±0.079 sec of each conditions. Also, the measurement results were shown with errors of 0.655±0.044 sec, 0.637±0.014 sec, and 0.662±0.013 sec, respectively.

• Korean Journal of Pharmacognosy
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• v.14 no.2
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• pp.60-63
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• 1983

Two prescriptions of 'Ssanghwa-Tang', Korean traditional medicine, and their individual crude drugs were studied on the analgesic and the anticonvulsionary effects. Two prescriptions showed very significant analgesic effects and the prescription B was more effective. Individual crude drugs had decreasing effects on the convulsion-start-time, but two prescriptions did not show significant activities.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.09a
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• pp.257-261
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• 2004

Recently, Pb free solder technologies are developed, and start using for many packaging items. But this technology contains many problems. They are very high re-flow temperature and high cost than normal solder paste. Specially, high re-flow temperature effects heavy damage to packaging and occur many crack to packaging. We developed special ACI (anisotropic conductive ink) that becomes substitution of solder paste. This technology cans adhesive lower temperature such as $120\~150^{\circ}C$. Adhesion time is very short, too. This technology is suitable for mass production.