• Journal of the Korea Institute of Information Security & Cryptology
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• 제23권5호
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• pp.909-917
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• 2013

CAPTCHA is an automated test to tell apart computers from human mainly for web services, and it has been evolved since the most naive form in which users are requested to input simple strings has been introduced. Though many types of CAPTCHAs have been proposed, text-based CAPTCHAs have been widely prevailed for user convenience. In this paper, we introduce new segmentation schemes and show an attack method to break the CAPTCHA of Naver that occupies more than 70% of the market share in search engine. The experimental results show that 938 trials out of 1000 have successfully analyzed, which implies that we cannot use the CAPTCHA anymore.

• Journal of Service Research and Studies
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• 제13권2호
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• pp.82-98
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• 2023

This study investigates consumers' perceptions when customers participate in the process of innovating new products or new services essential to companies in the era of the 4th industrial revolution. Specifically, this study investigates how consumers' product evaluation varies depending on two types of innovation for a company's new product development (technology-based innovation and market-based innovation) and two customer roles (as information providers and as co-developers) participated in the development process. The research questions are as follows: As technology-based innovation and market-based innovation are different types of innovations, will consumers' product evaluation vary depending on these different types of innovation? If customers participate in the development process of a new product reflecting each innovation, how will the information that the customer participated be perceived by other consumers? In addition, this customer participation method can serve as an information provider and a co-developer, and will consumers' evaluation of new products vary depending on this role? As a result of verifying the hypothesis using an experimental method, it shows that consumers' product evaluation differs significantly depending on the role of customers who participated in the process of developing new product development process. In other words, the results indicate that the case where customers participated as market information providers in the process of developing new products is more favorable to the new product evaluation than the case where they participated as co-developers of the new products. In addition, there is an interaction effect between the type of product innovation and the role of customer participation. To be specific, when a product reflecting technological innovation is released, there is no difference in consumers' product evaluation according to the roles of two different customer participations. However, when a market-based innovation product is released, product evaluation is more favorably perceived when customers participated as information providers than they were involved in the new product development process as co-developers. This study is of theoretical significance in that it distinguishes each type of innovation and verified how other consumers' perceptions vary depending on their role when customers participate in the innovation process. Finally, limitations and future study directions are suggested along with practical implications.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• 제18권1호
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• pp.31-46
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• 2023

This study classified and confirmed the learning modes about start-ups that are based on the accelerator's program which was focusing on the Korean accelerators in the ICT field targeting global market. Eight accelerator practitioners were interviewed who were in charge of operating programs for accelerators, qualitatively analyzing method of the interview was conducted. The interview results to identify various learning modes that accelerators provide to startups through programs. In order to identify and classify learning modes, the researcher reviewed various prior documents and using categories of experience accumulation, observation, experimentation, trial and error, and improvisation as a priori code for the qualitative analysis. The interview results were analyzed through a subject analysis. As the result of the study, the learning modes offered by the accelerator's programs to startups were confirmed, with two subcategories identified for each of the five categories: experiential, learning from others, experimental, trial and error, and improvisation. Given the limited research on accelerator programs and their main function, the main function of accelerators, this study identified the types of learning modes that offered by the accelerator's programs to startups from the perspective of learning. This study provides important insights into the types of learning modes that offered by the accelerator programs, which can help to improve our understanding of how accelerators support organizational learning for startups. Additionally, this information can be useful for startups considering in participating in the accelerator programs, as it can help them making informed decisions about their involvement.

• Journal of Korea Game Society
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• 제14권5호
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• pp.35-42
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• 2014

In the market of First Person Shooter (FPS) games, Massively Multi-player Online FPS games (MMOFPS) like 'PlanetSide 2' have been popular recently. Dead reckoning has been widely used in order to mitigate the network traffic overload for the game server with hundreds or thousands of people. This paper proposes the efficient analytical method to calculate the tolerable threshold angle of moving direction, which is one of the most important factors for character status updating when dead reckoning is used in MMOFPS games. The experimental results with game testers shows that the proposed method minimizes the position error for character moving and provides natural direction updates of characters.

• The Journal of the Korea Contents Association
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• 제19권3호
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• pp.80-88
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• 2019

With more emphasis on emotional communication with users in product design field, designers' clear and prompt grasp of user's emotion has become the core activity in product design research. To increase the flexibility applying emotion measurement in the process of product design, this study has used Facial Action Coding System (FACS) of behavioral emotion measurement method in product design evaluation. To select specimens, it has flexibly used the emotional product Image Map. Then this study has selected six product irritants inducing positive, negative and neutral emotions, and conducted FACS experiment with ordinary product users of 20 generations as the experimental subject, and analyzed users' emotional state in response to the irritants through their facial expressions. It also analyzes the advantages and disadvantages of FACS in the process of product design, such as "recording users' unconscious facial expressions" and puts forward some applicable schemes, such as "choosing a product stimulus with high user response". It is expected that this paper can be helpful to the flexibility of FACS as a method to predict user's emotion in advance at the trial stage of product design before launching them to the market.

• Journal of the Korean Geosynthetics Society
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• 제9권2호
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• pp.1-9
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• 2010

At present, the sand mat method is actively used for improvement of soft ground. But, there are some problems related with sand mat which has been used as a way to accelerate consolidation settlement. First of all, insufficiency of sand due to imbalances in market supply and demand is the one of the biggest problems, which makes price high of sand and delays a term of total construction work. Moreover, it is necessary to preserve integrity of environment from natural disruption caused by indiscreet quarrying and dredging operation to supply sand for soil improvement construction site. This paper presents the feasibility study to use of Precious Slag Ball instead of sand mat as the replacing material through the basic soil property tests, the medium of discharge capacity test and analysis of settlement property. It is also evaluates the performance of Precious Slag Ball as a sand mat in terms of discharge capacity, ground settlement by the K-Embank program based on field experimental work.

• Parasites, Hosts and Diseases
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• 제55권6호
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• pp.631-641
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• 2017

A survey was performed to investigate the infection status of zoonotic trematode (ZT) metacercariae in fish from a local market in Yangon City, Myanmar. A total of 264 fish (12 species) were collected through 4 times from December 2013 to June 2015. All collected fish were transferred to our laboratory on ice and examined by the artificial digestion method. More than 7 species of ZT metacercariae, i.e., Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus spp., Stellantchasmus falcatus, Pygidiopsis cambodiensis, and Procerovum sp. were detected. Metacercariae of H. taichui were collected in 58 (42.3%) out of 137 fish (5 species), and their average density was 42.9 per fish infected. Metacercariae of H. pumilio were detected in 96 (49.0%) out of 196 fish (9 species), and their average density was 23.6 per fish infected. H. yokogawai metacercariae were found in 40 (50.0%) out of 80 fish (5 species), and Centrocestus spp. metacercariae in 91 (50.8%) out of 179 fish (8 species), and their densities were 306 and 25.8 per fish infected, respectively. Metacercariae of S. falcatus and P. cambodiensis were detected only in mullets, Chelon macrolepis. A total of 280 Procerovum sp. metacercariae were found in 6 out of 12 climbing perch, Anabas testudineus. Morphological characteristics of adult flukes recovered from experimental animals were described. It has been first confirmed that fish from Yangon, Myanmar are commonly infected with various species of ZT metacercariae.

• Journal of Environmental Health Sciences
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• 제46권2호
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• pp.170-183
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• 2020

Objectives: This study was conducted to estimate a technology to reduce hydrogen sulfide (H₂S) in sewage odor using microbial deodorant. Methods: After injecting five commercially available microbial deodorants into fresh sewage, the concentration of hydrogen sulfide over time was measured using the headspace method. H₂S concentration in odor samples was measured using gas chromatograph/FPD. Calculated odor concentration and calculated odor intensity by H₂S concentration remaining after treatment with microbial deodorant were evaluated theoretically. Results: The rate of H₂S abatement by microbial deodorant differed depending on the experimental conditions and the type of deodorant, but it was found to range from 63 to 82%. Especially, two deodorants showed high H₂S reduction rates of over 80% on average. However, based on the best deodorant, the theoretically calculated odor concentration by H₂S after microbial deodorant treatment was 4,400 OU_k, and the theoretical odor intensity was also rated at 4 degrees or higher. Conclusions: In conclusion, microbial deodorant is considered to have a relatively high effect on reducing H₂S in sewage odor. However, even after treatment with microbial deodorant, calculated odor concentration and calculated odor intensity were relatively high. This is thought to be caused by other odorous substances besides H₂S.

• Journal of the Korean Electrochemical Society
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• 제15권3호
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• pp.115-123
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• 2012

As the market of lithium secondary batteries moves from mobile IT devices to large-format electric vehicles or energy storage systems, the strengthened battery specifications such as long-term reliability longer than 10 years, pack-level safety and tough competitive price have been required. Moreover, even though high power properties should also be achieved for hybrid electric vehicles, it is not easy to measure accurate power values at various conditions. Because it is difficult to choose a proper measurement method and its experimental condition is more complex comparing to capacity measurement. In addition, the power values are very sensitive to power duration time, state-of-charge (SOC) of cells, cut-off voltages, and temperatures, whereas capacity values are not. In this paper, we introduce three kinds of power measurement methods, hybrid pulse power characterization (HPPC) suggested by US FreedomCar, so-called J-pulse by Japan electric vehicle association standards (JEVS) and constant power measurement, respectively. Moreover, with pouch-type unit cells for HEV, experimental power data are discussed in order to compare each power measurement.

• Tribology and Lubricants
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• 제37권6호
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• pp.246-252
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• 2021

Among the engine components of an internal combustion engine, the valve train is a series of systems that supply intake gas to the combustion chamber and operate intake and exhaust valves that discharge exhaust gas. If excessive wear occurs in the valve train system, the suction and exhaust valves do not open and close on time, which leads to abnormal combustion and exhaust gas. In this study, we conduct experiments and analyses on friction and wear characteristics of the valve train system. Moreover, we experimentally study the correlation between the pinball and pinball cap on engine oil lubrication, friction experiment, wear amount analysis, and surface analysis. Specifically, we experiment using Ball on reciprocating tribo-tester and apply commercial engine oil sold on the market engine oil. We construct the experimental conditions for each new oil and oil. Accordingly, the completed specimen was subjected to a confocal microscope to check the wear volume, observe the surface of the specimen, and confirm the elemental components using a scanning microscope (SEM) and an energy dispersion X-ray spectrometer (EDS). Through this experiment, we analyze the friction and wear characteristics of valve train components according to engine oil grade, and the obtained data serve as an effective engine oil management method.