• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.66-73
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• 2017

Empirical erosion models like Universal Soil Loss Equation (USLE) models have been widely used to make spatially distributed soil erosion vulnerability maps. Even if the models detect vulnerable sites relatively well utilizing big data related to climate, geography, geology, land use, etc within study domains, they do not adequately describe the physical process of soil erosion on the ground surface caused by rainfall or overland flow. In other words, such models are still powerful tools to distinguish the erosion-prone areas at large scale, but physics-based models are necessary to better analyze soil erosion and deposition as well as the eroded particle transport. In this study a physics-based soil erosion modeling system was developed to produce both runoff and sediment yield time series at watershed scale and reflect them in the erosion and deposition maps. The developed modeling system consists of 3 sub-systems: rainfall pre-processor, geography pre-processor, and main modeling processor. For modeling system validation, we applied the system for various erosion cases, in particular, rainfall-runoff-sediment yield simulation and estimation of probable maximum sediment (PMS) correlated with probable maximum rainfall (PMP). The system provided acceptable performances of both applications.

• Journal of Biomedical Engineering Research
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• v.26 no.1
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• pp.43-47
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• 2005

We have developed a small bore x-ray CT for small animal imaging with a linear x-ray detector array and small-scale slip rings. The linear x-ray detector array consists of 1024 elements of 400□m×400□m with a gadolinium oxysulfide (GOS) scintillator on top of them. To avoid use of expensive large diameter slip rings for projection data transmission from the X­ray detector to the image reconstruction system, we used the wireless LAN technology. The projection data are temporally stored in the data acquisition system residing on the rotating gantry during the scan and they are transmitted to the image reconstruction system after the scan. With the wireless LAN technology, we only needed to use small-scale slip rings to deliver the AC electric power to the X-ray generator and the power supply on the rotating gantry. The performances of the small animal CT system, such as SNR, contrast, and spatial resolution, have been evaluated through experiments using various phantoms. It has been experimentally found that the SNR is almost linearly proportional to the tube current and tube voltage, and the minimum resolvable contrast is less than 30 CT numbers at 40kVp/3.0㎃. The spatial resolution of the small animal CT system has been found to be about 0.9Ip/㎜. Postmortem images of a piglet is also presented.

• Journal of Navigation and Port Research
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• v.32 no.10
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• pp.777-783
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• 2008

Nowadays wavelet transforms are widely used for the analyses of PIV velocity vector fields. This is bemuse the wavelet provides not only spatial information of the velocity vectors but also of time and frequency domains. In this study, a discrete wavelet trC1f1$form has been applied to real PIV images of bubbly flows. The vector fields obtained by a self-made cross-correlation PIV algorithm were used for the discrete wavelet transform The performances of the discrete wavelet transform is investigated by changing the level of power of discretization. The decomposed images by the wavelet multiresolution showed conspicuous characteristics of the bubbly flows according to the level changes. The high spatial bubble concentrated area could be evaluated by the constructed discrete wavelet transform algorithm, at which high leveled wavelets could play a dominant roles to reveal the flow characteristics.

• Korean Medical Education Review
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• v.18 no.2
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• pp.90-98
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• 2016

Assessment tools for non-academic qualities such as ethics frequently employ hypothetical scenarios to lay out a contextual framework underlying the corresponding criteria of assessment. Due to the context-specific nature of the assessment criteria, details of the scenarios become very important in obtaining accurate results. This study aims to explore how medical school applicants differ in ethical decision making depending on the types of ethical dilemma scenarios, and how they correlate with academic achievements after admission. In 2014, all 82 applicants invited for an admission interview for a graduate-entry program were asked to complete a questionnaire comprised of 13 hypothetical scenarios. There were three domains (unethical business decisions, unethical academic decisions, and sexual quid pro quos) and participants were made to choose between the profitable-but-unethical choice or the unprofitable-but-ethical choice, using a four-point Likert-type scale. On average, tendencies toward unethical decisions were lowest for sexual favors ($1.34{\pm}0.46$), and highest for gaining academic advantages ($2.22{\pm}0.56$). Unethical decisions for academic advantages and sexual benefits showed significant correlation respectively with the female gender and those who graduated from overseas universities. In addition, the propensity for choosing unethical academic decisions was significantly correlated with high academic achievements in medical school (r=0.396). Not only does this study demonstrate that different levels of ethical decision making depend on the scenarios, but also those differences may be a determinant factor in subsequent academic performances in medical school. In conclusion, given the possible influence of the details of the hypothetical scenarios to the applicant's responses, careful consideration must be given during their development.

• Journal of Korea Port Economic Association
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• v.31 no.2
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• pp.1-21
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• 2015

This study verifies the change in market conditions in the Korea-China and Korea-Japan car ferry routes. Variation in historical development has led to differences in the lifecycle stages of these two car ferry shipping markets. However, previous studies have focused on individual car ferry routes rather than offering a more general understanding of this market. Based on the foregoing, we investigate the international car ferry market conditions from/to Korean ports, assess the management performances of car ferry companies, analyze the lifecycle stages of each car ferry route, and offer insights into the future of these markets. We show that the competitive market conditions and demands of passengers and cargoes differ between these routes. As for the market stage, we conclude that the Korea-China route is entering a mature market, whereas the Korea-Japan route is entering a declining stage.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.168-176
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• 2015

Trends of integrating products and services lead to the emergence of Product-Service System (PSS). To implement and embody a PSS solution in new product development, a comprehensive design framework is allowed designers to facilitate the design factors of the PSS in complex business environments. A physical product, containing functionalities for services, is the role of medium between customers and a manufactures. Customers can access those metaphysical interfaces to utilize the product fully or expand its performances. The PSS is aiming to prolong its lifecycle while maintaining its expected quality. Since the quality can be represented as a measure which belongs to user's perspective, guaranteeing certain level of quality can be interpreted to sustaining customer satisfaction. The objective of this paper is to propose a PSS design framework to identify design factors for developing products and services by integrating object-oriented concepts and blueprinting in context of a business ecosystem. The proposed model is developed based on relationship products and services matching with their design factors. The products and the services are then brought together to form a PSS. Functions and processes can be categorized to identify the design factors in different levels using the object-oriented concepts. Objected-oriented concepts provide PSS analysis tools for describing a business process or a workflow process in the PSS. The blueprint is used to identify the relationships between the products functions and the service processes that are offered as part of a job. To demonstrate of the effectiveness of the proposed model, we use a case study involving a smart phone.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.3
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• pp.60-71
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• 2004

Nowadays, We have had a growing interest in high-speed vessels' because it is very important to save time and cost in marine transportation. The development of hull form for high-speed vessels is high priority to secure the competitive power for the transportation of cargos. Therefore, the demand of the high-speed vessels is gradually increased, but the conventional hull forms are limited by rapidly increasing resistance upon the increase of ship speed in high-speed region. Therefore, new concepts for the hull form of high-speed vessels have been requested. One of the derived hull forms for that demand is the hull form of trimaran type. Trimaran has a very slender main hull as compared with conventional single hull so that is reduced in wave resistance. The slender main hull has the undesirable characteristics of stability, but two side hulls make up for the week points in the stability. That is, trimaran is able to have desirable performances for the resistance and stability. In this paper, for the design of 200TEU class container vessel with trimaran type, which will be cruised in Yellow-Sea region, firstly a preliminary hull is designed, and the model test is carried out with the variation of side hull position. From the experience of the preliminary hull form design, an improved hull form for the 200TEU container are designed, and the model tests are carried out. Also, a numerical computation technique is adopted for the simulation of flow phenomena around the designed hull forms. The final hull form is compared with existing ships for the resistance performance from the computation with computer and ship model tests.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.6
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• pp.667-674
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• 2009

The researches on the development of composite material underwater vehicle propeller have been actively attempted for the reduction of radiation noise with outstanding damping effects. Composite material propellers have almost been designed and produced by the foreign experts, and it is difficult to obtain the related informations about their flow, vibration, material characteristics because they are treated as the secrets with close relationship to the military technology, especially in the case of underwater vehicles. For the security of domestic manufacture of composite material propeller and the comparison and examination of its performance and radiation noise characteristics with those of German CONTUR composite material propeller, two propellers were self-produced according to the fiber weaving and array using compressible molding process and their self performances and radiation noise characteristics were measured. The mean fluctuations of blade tip of self-produced composite material propeller were increased and the radiation noises in the low frequency band were reduced compared to those of CONTUR, which could be estimated as the change of material characteristics and also be thought to be used for the future research informations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.117-122
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• 2021

Autonomous driving allows cars to drive without people and is being studied very actively thanks to the recent development of artificial intelligence technology. Among artificial intelligence technologies, deep reinforcement learning is used most effectively. Deep reinforcement learning requires us to build a neural network using an appropriate activation function. So far, many activation functions have been suggested, but different performances have been shown depending on the field of application. This paper compares and evaluates the performance of which activation function is effective when using deep reinforcement learning to learn autonomous driving on highways. To this end, the performance metrics to be used in the evaluation were defined and the values of the metrics according to each activation function were compared in graphs. As a result, when Mish was used, the reward was higher on average than other activation functions, and the difference from the activation function with the lowest reward was 9.8%.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.197-206
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• 2021

This study examined the networked structure and message types of newspapers advertisements in which universities have put in Daegu and Gyeongbuk provinces in Korea. Data were collected from July to September in 2020. As a result, universities preferred newspapers located in Daegu and Pohang areas. Next, universities have emphasized their cooperations with industries, basic competency capacities, and specialization programs in the advertising messages. When analyzing the findings in terms of university level, key words related to mid- to long-term development plans often appeared in the four-year schools. On the other hand, two or three-year universities frequently used an appeal that emphasized tangible performances. The findings showed the way in which the direction of university newspaper advertisements have been set in line with the rapidly changing environment.