• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.261-274
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• 1999

Objectives: The purpose of this study was to evaluate the optimal distance and angle of observers by modulation transfer functions(MTFs) and receiver operating characteristics(ROCs), Material and Methods: Digital periapical radiograms were taken from 43 patients who have dental diseases(19 patients : dental caries. 12 patients : periapical lesions, 12 patients : periodontal diseases). Segmental images(4×4cm) were evaluated by 4 MTFs and ROC analysis. Results: The optimal distance(magnification) using MTF by Mannos & Sakrison was 12.97. and those by Nill. Ngan and Rao were 8.39, 4.78. 5.84 respectively. The optimal distance obtained from 4 radiologists by ROC analysis was 32cm(Az value: 0.89). and it was 40cm(Az value: 0.78) from 4 non-radiologists. There were significant differences of Az values between 4 radiologists and 4 non-radiologists at 24. 32 and 40cm (P<0.05). No significant differences of optimal distances were observed using 4 MTFs among +20, +10, 0, -10, -20 degrees(P>0.05). The optimal angle obtained from 4 radiologists by ROC analysis was +20 degree(Az value: 0.91). and no significant differences of Az values were observed among +20, +10, 0, -10 and -20 degrees(P>0.05). The optimal angle obtained from 4 non-radiologists by ROC analysis was 0 degree(Az value : 0.81). and no significant differences of Az values were observed among +20, +10, 0, -10 and -20 degrees(P>0.05). And there was significant difference of Az value between 4 radiologists and 4 non-radiologists at +20 degree(P<0.05). but no significant differences of Az values were observed among +10, 0, -10 and -20 degrees(P>0.05).

• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.315-320
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• 2006

It is well known that the ship manoeuvring motion is greatly affected by hydrodynamic forces and moments acting between two vessels passing too close to each other in confined waters, such as in a harbour or narrow channel. This interaction between two vessels could be assumed to be the functions of the longitudinal distance, transverse distance and their speeds. The aim of this study is to calculate the interaction between two vessels passing close to each other on parallel courses by simulation, and to estimate the effect of rudder action and time at collision through simulation under the condition of various longitudinal distances and different speed-ratios of the two vessels.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.37-44
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• 2004

This paper represents a new approach for the protective relay of power transmission lines using a Artificial Neural Network(ANN). A different fault m transmission lines need to be detected classified and located accurately and cleared as fast as possible. However, The protection range of the distance relay is always designed on the basis of fixed settings, and unfortunately these approach do not have the ability to adapt dynamically to the system operating condition. ANN is suitable for the adaptive relaying and the detection of complex faults. The backpropagation algerian based multi-layer protection is utilized for the teaming process. It allows to make control to various protection functions. As expected, the simulation result demonstrate that this approach is useful and satisfactory.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3434-3439
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• 2015

As a criterion of information theoretic learning, the Euclidean distance (ED) of two error probability distribution functions (minimum ED of error, MEDE) has been adopted in nonlinear (decision feedback, DF) supervised equalizer algorithms and has shown significantly improved performance in severe channel distortion and impulsive noise environments. However, the MEDE-DF algorithm has the problem of heavy computational complexity. In this paper, the recursive ED for MEDE-DF algorithm is derived first, and then the feed-forward and feedback section gradients for weight update are estimated recursively. To prove the effectiveness of the recursive gradient estimation for the MEDE-DF algorithm, the number of multiplications are compared and MSE performance in impulsive noise and underwater communication environments is compared through computer simulation. The ratio of the number of multiplications between the proposed DF and the conventional MEDE-DF algorithm is revealed to be $2(9N+4):2(3N^2+3N)$ for the sample size N with the same MSE learning performance in the impulsive noise and underwater channel environment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.55-60
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• 2006

It is well known tint the ship manoeuvring motion is greatly affected by hydrodynamic forces and moments acting between two vessels passing too close to each other in confined waters, such as in a harbour or narrow channel. This interaction between two vessels could be assumed to be the functions of the longitudinal distance, transverse distance and their speeds. The aim of this study is to calculate the interaction between two vessels passing close to each other on parallel courses by simulation, and to estimate the effect of rudder action and time of collision through simulation under the condition of various longitudinal distances and different speed-ratios of the two vessels.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.75-80
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• 2021

Positioning technology is performing important functions in augmented reality, smart factory, and autonomous driving. Among the positioning techniques, the positioning method using beacons has been considered a challenging task due to the deviation of the RSSI value. In this study, the position of a moving object is predicted by training a neural network that takes the RSSI value of the receiver as an input and the distance as the target value. To do this, the measured distance versus RSSI was collected. A neural network was introduced to create synthetic data from the collected actual data. Based on this neural network, the RSSI value versus distance was predicted. The real value of RSSI was obtained as a neural network for generating synthetic data, and based on this value, the coordinates of the object were estimated by learning a neural network that tracks the location of a terminal in a virtual environment.

• The Journal of Fisheries Business Administration
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• v.5 no.1
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• pp.9-42
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• 1974

Korea is a peninsular country surrounded by seas on three sides, and the fishing industry has carried out the service of suppling to the people with important anima protein. The distribution of fishery products has very complicated structures, because the production is in charge of small producers scattering along the coast all over the country, while consumpstion is made by separate homes in areas away from producing district. The relation between these two factors the structures make very complicated. The most typical and special structures of fishery distridution are distinguished in two, that is, one is landing market, the other is inland market. Landing markets have been monopolized by fishermen's cooperatives, providing with landing facilities and building sites. Fish markets played not only an important role in the landing, but distribution and price determination of catches by auction or tender. Inland markets are two types of wholesale market in consuming center, one is the terminal market for urban consumers, the other type is the local market for rural consumers. Fundamental functions of landing markets are gathering, assessment, and distribution functions. Gathering function is in charge of wholesaler in fishery cooperative. Gathering amounts are equal to gathering capacity of wholesaler and transact ability of licensed dealers as shown below model. Gathering amount=f.gathering capacity(=pre price.landing facility.account of wholesaler.distance of fishing ground.conveniency purchasing.home port)=fㆍ transact ability of licensed dealers≒f.population or port, and table 1 indicates these relationship. Assessment and distribution functions are in charge of licensed dealers in consumption side. Assessment function should bring the value in production activity through the auction between the cooperative seller and the licensed dealer as buyer. For fair trade transaction in auction, the free competition is supposed to be a prerequisite among the licensed dealers. The ideal condition for free competition is sameness in the scale of buying amount by licensed delaers, but it is almost impossible to attain its goal in actual marketing.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.2
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• pp.111-118
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• 2002

In GMAW(Gas Metal Arc Welding) processes, bead geometry (penetration, bead width and height) is a criterion to estimate welding quality, Bead geometry is affected by welding current, arc voltage and travel speed, shielding gas, CTWD (contact-tip to workpiece distance) and so on. In this paper, welding process variables were selected as welding current, arc voltage and travel speed. And bead geometry was reasoned from the chosen welding process variables using neuro-fuzzy algorithm. Neural networks was applied to design FLC(fuzzy logic control), The parameters of input membership functions and those of consequence functions in FLC were tuned through the method of learning by backpropagation algorithm, Bead geometry could he reasoned from welding current, arc voltage, travel speed on FLC using the results learned by neural networks. On the developed inference system of bead geometry using neuo-fuzzy algorithm, the inference error percent of bead width was within ${\pm}4%$, that of bead height was within ${\pm}3%$, and that of penetration was within ${\pm}8%$, Neural networks came into effect to find the parameters of input membership functions and those of consequence in FLC. Therefore the inference system of welding quality expects to be developed through proposed algorithm.

• Fashion & Textile Research Journal
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• v.14 no.1
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• pp.136-143
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• 2012

The purpose of this study was to investigate the influence of physical functions of elderly people on their clothing behavior and to provide basic information about manufacturing comfortable apparels for the elderly. A total of 219 people, with ages between 60s and 70s, participated in the survey and in the experiment to correlate their tendency of wearing clothes with the state of their physical functions. About 78.5% of the elderly showed eyesight deterioration in the subjective evaluation. Elders in their 60s raised their arms higher up in overhead reach, and showed shorter distance between middle fingertips in behind back stretch and in back scratch than elders in their 70s. Also, the former stretched farther to the floor in standing trunk flexion, and maintained more steady in one leg stand and in tandem stance than the latter. The narrower the movement range of the upper limb joints was, the more the elderly preferred upper garments with full front opening to those with half or no opening. The more inflexible the upper limbs and waist and the more unbalanced the body was, the more likely the elderly put on pants while sitting on the floor. The time taken to button up the shirt and to put on and take off pants showed a positive correlation with the overhead reach, the behind back stretch, the back scratch and the standing trunk flexion, whereas the former showed a negative correlation with the one leg stand and the tandem stance.

• Korea Journal of Hospital Management
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• v.25 no.3
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• pp.38-52
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• 2020

Purpose: The purpose of the study is to suggest the main functions and implications of public hospitals to effectively respond to the future epidemic crisis based on analyzing the accessibility to designated Coronavirus Disease 2019 (COVID-19) medical institutions of Seoul and examining the main features of the quarantine of Seoul municipal hospitals. Method: To analyze the response and function of Seoul municipal hospitals, we reviewed the Infectious Disease Control and Prevention ACT, 258 articles of Seoul Metropolitan Government press releases from January to the end of April, 48 articles of Seoul Metropolitan Government's daily newsletters, 2019 Health Bureau Budget report. We also referred to internal data of Seoul Children's Hospital, Seoul Seobuk Hospital, and Seoul Eunpyeong Hospital during the same period. Besides, the accessibility to medical institutions was analyzed by using the COVID-19 data which was announced daily basis. Results: The accessibility of COVID-19 patients living in the Southeastern part of Seoul to a medical institutions was 16.2km on a distance basis, and it was the lowest accessibility among four regions of Seoul since it took about 40 minutes by car. On the other hand, patients living in the Northeast part had the highest accessibility, as the access to medical institutions was 10.7km and 27 minutes by car. Also, the main functions of the municipal hospital of Seoul against COVID-19 were to shift the public hospital function to COVID-19 patients only hospitals, to perform the epidemiological investigation by medical doctors, and to support the operation of self-isolation facilities, community treatment centers and triage rooms of community health centers. Conclusion: Through the experience of COVID-19, we suggested that the functions of public hospitals will be reorganized as the reinforcement of infectious disease treatment and mental health for quarantined patients, cooperation with private hospitals, supporting for strengthening community health capacity and preparation for another epidemic.