• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.97-104
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• 2018

In the conventional direction finding, the antenna is installed at a high position on the ground to detect the position of the target with the environment of the LOS(Line of Sight) as much as the signal receiving environment. However, in order to configure such environment, high cost and installation time were required. In this paper, we use TDOA(Time Difference of Arrival) technique to utilize drones in direction finding, so that four drones can be used for directions finding simulation. Simulations based on drone and TDOA direction finding were constructed using additional signal processing Taylor series and Exact Interactive Algorithm. In the simulation, the receiving power is defined by using the 800MHz path-loss model using the GPS information of the ground direction detection, and the position estimation performance is analyzed when the TDOA technique, the Taylor series, and the Exact Interactive Alogrithm are applied.

• Spatial Information Research
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• v.19 no.6
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• pp.111-121
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• 2011

In this paper, we proposes a sensor node positioning algorithm that utilizes the geo-spatial elements and considers the factors to represent the propagation loss generated by the various obstacles in the urban wireless environments. First, we measures the propagation loss about the radio frequencies in major road of the urban, and defines the correlation between the measured loss and the environment information for the road and its surrounding get from Urban GIS. Secondly, through the utilization of the loss-environment correlation, we describes the detailed instruction for requiring the radio coverage decision and deploy system implementation for the wireless sensor node in urban. By the consideration of interference factor by the building and the linear structure of road, we can evaluate the path loss below 5dB RMS error. And, we proposes the way to revise the sensor node deployment based on the corelation and the measured path loss.

• Imaging Science in Dentistry
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• v.53 no.2
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• pp.137-144
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• 2023

Purpose: This study aimed to evaluate the anatomic circle around the impacted lower third molar to show, document, and correlate essential findings that should be included in the routine radiographic assessment protocol as clinically meaningful factors in overall case evaluation and treatment planning. Materials and Methods: Cone-beam computed tomographic images of impacted lower third molars were selected according to specific inclusion criteria. Impacted teeth were classified according to their position before assessment. The adjacent second molars were assessed for distal caries, distal bone loss, and root resorption. The fourth finding was the presence of a retromolar canal distal to the impaction. Communication with the dentist responsible for each case was done to determine whether these findings were detected or undetected by them before communication. Results: Statistically significant correlations were found between impaction position, distal bone loss, and detected distal caries associated with the adjacent second molar. The greatest percentage of undetected findings was found in the evaluation of distal bone status, followed by missed detection of the retromolar canal. Conclusion: The radiographic assessment protocol for impacted third molars should consider a step-by-step evaluation for second molars, and clinicians should be aware of the high prevalence of second molar affection in horizontal and mesioangular impactions. They also should search for the retromolar canal due to its associated clinical considerations.

• Journal of the korean academy of Pediatric Dentistry
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• v.21 no.2
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• pp.540-546
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• 1994

The authors treated three patients who chiefly complained functional anterior crossbite due to premature loss of primary molars by using removable space maintainer and functional appliances. In orthodontic practice, the mandibular rest position and the possibility of taking construction bite have been as the criteria for evaluation of functional factors involved in anterior crossbite. Functional anterior crossbites, if left untreated, may have deleterious effects on the development and function of craniofacial complex and TMJ. Objectives of the treatment were as follows: 1) to recover vertical dimension 2) to eliminate functional disharmony 3) to correct anterior reversed occlusion 4) to attain good facial esthetics 5) to prevent unfavorable growth of jaw & dentition Characterized craniofacial morphology resulting from the premature loss of deciduous molars could be recovered following the correction of crossbite. Therefore, it is recommended that in orthodontic diagnosis of functional anterior crossbite due to premature loss of deciduous molars, the craniofacial abnormality affected by that should be considered.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.51
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• pp.133-158
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• 2011

The purpose of this study is to analyze one of CIETEC(China International Economic and Trade Arbitration Commission) Award on the dispute arising from Cotton Sale Contact which deals with damages and reduction of the price. Especially this case focused on the effect of reduction of the price to damages. The purpose of damages is to place the aggrieved party in as good a position as if the other party had properly performed the contract. So court costs and attorney's fee should be regarded as the loss, because these are caused by consequence of the breach which is recoverable. With the same reason, overpaid taxes should also regard as the loss. It is not impossible, however, to claim both damages and reduction of the price for same loss at the same time. It means buyer could not claim damages for the same loss, once he already claimed reduction of the price. So Korean companies should consider which remedy is proper to himself under the circumstances. He should choose reduction of the price when market price is down. In case of rising market price, he should consider follows: first, it is better to choose damages based on current price(Art.76), if upswing of non-conformity price is higher then upswing of market price. Second, it is better to choose general rule for measuring damages(Art.74), if upswing of market price is higher then upswing of non-conformity price.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.16-23
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• 2019

Cooking oil in kitchen-fog is the most harmful factor to the health of a cook. The proposed filter is a tool that protects the cooked state, to prevent users from inhaling oil mist in the kitchen. Due to efficiency issues, existing filters are of the mesh type or baffle type. In this paper, CFD analysis is carried out to select a filter with low pressure loss and low efficiency, and to attach the sub-filter to improve efficiency. The results of the analysis on the collection efficiency and pressure loss of three sub-filters, i.e., circle type, droplet type, and cone type, showed that the collection efficiency was 64.09% and the pressure loss was 1.26 mmAq when the circle type sub-filter was applied. The position of the sub-filter showed the best efficiency and pressure loss when it was located at the bottom of the center of the gap of the main filter.

• Journal of Mechanical Science and Technology
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• v.18 no.10
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• pp.1700-1711
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• 2004

Piston friction is one of the important but complicated sources of energy loss of a hydraulic axial piston machine. In this paper, two formulas are derived for estimating instantaneous piston friction force and average piston friction moment loss. The derived formula can be applicable for piston guides with or without bushing as well as for axial piston machines of motoring and pumping operations. Through the formula derivation, a typical curve shape of friction force found from several experimental measurements during one revolution of a machine is clearly explained in this paper that it is mainly due to the equivalent friction coefficient dependent on its angular position. Stribeck curve effect can easily be incorporated into the formula by replacing outer and inner friction coefficients at both edges of a piston with the coefficient given by Manring (1999) considering mixed/boundary lubrication effects. Novel feature of the derived formula is that it is represented only by physical dimensions of a machine, hence it allows to estimate the piston friction force and loss moment of a machine without hardworking experimental test.

• Journal of the Korea Safety Management & Science
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• v.21 no.2
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• pp.15-23
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• 2019

Among service industries of knowledge based economic era, the roles of educational service field are becoming more important and standard of educational service makes a direct effect on economic development and social growth. Therefore, accurate measurement of service quality is the most important assignment and the measurement of the service quality remains difficult assignment. So, this researcher classified quality attributes applying weighted value and found potential satisfaction level(PSL) and potential customer demand improvement index(PCDI) for trainees participating in national manpower business so as to suggest measurement of service quality and easiness of use and then, calculated satisfaction position and opportunity cost by quality factor with Taguchi's loss fraction. And, improvable satisfaction level was measured, opportunity cost by degree of customer dissatisfaction was quantitatively measured, and a model that can indicate with economic factors was suggested. In addition, methodology of measuring quality cost that can be reduced by quality improvement and direction of strategic decision-making for deciding items to be improved preferentially were suggested with qualitative index that can indicate the degree of customers' dissatisfaction by loss.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1760-1768
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• 2022

When gamma-camera sensor modules, which are key components of radiation imagers, are derived from the coupling between scintillators and photosensors, the light collection efficiency is an important factor in determining the effectiveness with which the instrument can identify nuclides via their derived gamma-ray spectra. If the pixel area of the scintillator is larger than the pixel area of the photosensor, light loss and cross-talk between pixels of the photosensor can result in information loss, thereby degrading the precision of the energy estimate and the accuracy of the position-of-interaction determination derived from each active pixel in a coded-aperture based gamma camera. Here we present two methods to overcome the information loss associated with the loss of photons created by scintillation pixels that are coupled to an associated silicon photomultiplier pixel. Specifically, we detail the use of either: (1) light guides, or (2) scintillation pixel areas that match the area of the SiPM pixel. Compared with scintillator/SiPM couplings that have slightly mismatched intercept areas, the experimental results show that both methods substantially improve both the energy and spatial resolution by increasing light collection efficiency, but in terms of the image sensitivity and image quality, only slight improvements are accrued.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.625-631
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• 2010

In this paper, robustness performance of SNUR message is compared with those of existing ones, RTCM(Radio Technical Commission for Maritime Services) v2 MT(Message Type) 18/19 and MT 20/21 under a poor broadcast condition such as temporary data loss or disconnection We defined the temp oral data loss as 2 second delay and reconnection after disconnection as 7 second latency, and then evaluated its robustness for each latency case by double differentiating the observables. Our result shows that SNUR protocol method can reduce the latency error of the existing RTCM messages by 30~60%. Moreover, a rover using SNUR message, whose latency error is bounded within 1/4 L1 wave length, can figure out its own fixed position continuously in spite of 7 second disconnection, while the other using RTCM message, whose error is larger than half wave length, cannot keep its previous fixed solution.