• Current Optics and Photonics
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• v.1 no.5
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• pp.538-543
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• 2017

Progressive addition lenses (PAL) have very wide application in the modern glasses market. The unique progressive surface can make a lens have progressive refractive power, which can meet the human eye's different needs for distance-vision and near-vision. According to the national glasses fabrication standard, the difference between actual optical power after fabrication and nominal design value should be less than 0.1D over the lens effective area. The optical power distribution of PAL is determined directly by the surface. Consequently, the surface processing accuracy requirement is proposed. Beginning from the surface expressions of progressive addition lenses, the relationship equations between the surface sag and optical power distribution are derived. They are demonstrated through tolerance analysis and test of an example progressive addition lens with addition of 2.09D (5.46D-7.55D). The example addition surface is fabricated under given accuracy by a single-point diamond ultra-precision machine. The optical power of the PAL example is tested with a focal-meter after fabrication. The optical power addition difference between test result and design nominal value is 0.09D, which is less than 0.1D. The derived relationship between the surface error and optical power is verified from the PAL example simulation and test result. It can provide theoretical tolerance analysis proof for the PAL surface fabricating process.

• Current Optics and Photonics
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• v.2 no.3
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• pp.250-260
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• 2018

A pressure wave created by the photoacoustic effect is affected by the medium and by laser parameters. The effect of these parameters on the generated pressure wave can be seen by solving the photoacoustic wave equation. These solutions which are examined in the time domain and the frequency domain should be considered by researchers in acoustic sensor design. In particular, frequency domain analysis contains significant information for designing the sensor. The most important part of this information is the determination of the operating frequency of the sensor. In this work, the laser parameters to excite the medium, and the acoustic signal parameters created by the medium are analyzed. For the first time, we have obtained solutions for situations which have no frequency domain solutions in the literature. The main focal point in this work is that the frequency domain solutions of the acoustic wave equation are performed and the effects of the frequency analysis of the related parameters are shown comparatively from the viewpoint of using them in acoustic sensor designs.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.5
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• pp.467-476
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• 2020

Indoor space has been one of the focal points for geospatial research as various factors such as increasing demands for application and demand for adaptive response in emergencies have arisen. IndoorGML (Indoor Geography Markup Language) has provided a standardized method of representing the topological aspect of micro-scale environments, with its extensive specifications and flexible applicability. However, as more real-world problems and needs demand attention, suggestions to improve this standard, such as representing IndoorPOI (Indoor Points of Interest), have arisen. Hence, existing algorithms and functionalities that we use on perceiving these indoor spaces must also adapt to accommodate said improvements. In this study, we explore how to define spatial neighborhoods in indoor spaces represented by an integrated IndoorGML and IndoorPOI data. We revisit existing approaches to combine the aforementioned datasets and refine previous approaches to perform neighborhood spatial queries in 3D. We implement the proposed algorithm in three use cases using sample datasets representing a real-world structure to demonstrate its effectiveness for performing indoor spatial analysis.

• 대한예방의학회:학술대회논문집
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• 1994.02b
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• pp.7-11
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• 1994

Twenty years ago, the American Journal of Epidemiology published David Sackett's brief description of. clinical epidemiology and its practitioners [1]. This commentary was a useful focal point for an emerging discipline. By 1983, with clinical epidemiology already thriving in many academic medical centres, Walter Holland called into question both the term, 'clinical epidemiology', and the nature of the discipline [2]. More recently, clinical epidemiology has drawn strong criticism from John Last, a noted academician whose contributions include the editorship of the Maxcy-Rosenau Textbook of Public Health. Writing in the Journal of Public Health Policy in 1988 [3], Last referred to the 'uncritical enthusiasm' for clinical epidemiology in medical schools as 'a danger to health', and staked. a claim to the term 'epidemiology' as appropriate only to the description of what classical or population epidemiologists do. Faced with such views, practitioners and proponents of clinical epidemiology can respond in three ways. They can ignore the criticism, and go on about their business. They can reaffirm their differences and resort to defensive rhetoric. Or, the critique can become an opportunity for reflection about the nature of clinical epidemiology and its relations with sister disciplines in modem medical schools. The latter course is followed here by four physicians who-despite diverse backgrounds and interests-all consider their work to be in the field of clinical epidemiology.

• Journal of the Korean Society for Library and Information Science
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• v.17
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• pp.261-273
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• 1989

The study attempted to determine if the effectiveness of bibliographic 'instruction would be different among student groups, divided by grade levels, major areas of study, and the level of library skills posessed before the instruction. The focal point of the investigation was the degree of improvement demonstrated by the changes in mean score of each group after taking bibliographic instruction. Sangmyong Women's University students who have taken the bibliographic instruction course for credit were the subjects of the study. Students' library skills were measured prior to the bibliographic instruction and post-test was followed. And the measured was based on the 'Library skills Test' developed by the Illinois Association of College and Research Libraries. Three hypotheses in the study were tested statistically by ANOVA. The followings are the results of the analysis: (1) There were no significant differences in bibliographic instruction effectiveness among student groups divided by grade levels; (2) There were significant differences (p<.01) in bibliographic instruction effectiveness among student groups divided by major areas of study. Bibliographic instruction was more effective for humanities or social sciences majors than for performing arts or physical education majors; (3) There were significant differences (p<.001) in bibliographic instruction effectiveness among student groups divided by the initial library skills. Obviously, bibliographic instruction was more effective for the students in bottom quartile than those in top quartile or middle quartiles. Finally, limitations of the study, recommendations based on the results and area for future research are briefly examined.

• The Journal of Engineering Geology
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• v.11 no.2
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• pp.205-214
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• 2001

A simple automated measuring method for planar or linear features on the rock excavation surface is presented. Attitude of the planar and linear feature is calculated from 3D coordinates of points on the structures. Spatial coordinates are calculated from overlapped stereo images. Factors used in the calculation are (1) local coordinates of the left and right images, (2) the focal length of cameras, and (3) the distance between two cameras. A simple image capturing device and an image treatment routine coded by Visual Basic and GIS components are constructed for the remote measurements, The methodology shows less than 1 cm error when a point is measured from 179 cm in distance. The methodology is tested at the excavation site in PaiChai University. Remotely measured result matches well with the manual measurement within the reasonable error range.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.82-88
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• 2015

In recent years, numerous studies have attempted to find and explore the auxiliary brake and the oil pressure type and electrical type are mainly used. However, the model proposed here is to self-excited eddy current brake. The advantage of this is it does not require an external power supply and can be produced to reduce the size than others. This self-eddy current brake consists of RLC circuit so resistance, inductance and capacitance value can be considered a fixed value. But, inductance and resistance value changes depending on the shape, temperature and magnetic alteration. Therefore, in this paper, the focal point is characteristic analysis according to the parameter variations. Also, using this result, this paper explains how to estimate the capacitance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.921-925
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• 2007

This paper investigates the information related to the radiated sounds during treatment using the extracorporeal shock wave lothotriptor(ESWL). First, we observe the vibration of the objects from the radiated sounds and extract the information about the change of the peak frequency from the relation between the vibration and the radiated sounds. Next, we observe the change of the peak frequency according to the position of the focus and demonstrate that it is more difficult to vibrate objects exactly at the focal point than above or below the focus of the ESWL device. Lastly, we analyze the relation between the cavitation and the radiated sounds and examine the benefiting condition for the object fragmentation.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.683-694
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• 2018

Subduction has been the focal point of numerical studies for decades because it plays an important role in the Earth's mass and energy circulations and generates earthquakes and arc volcanoes which are closely related to the human lives. Among the studies on subduction, numerical modeling has been broadly applied to the quantitative studies on the subducting slab in the mantle which cannot be directly observed. In this study, we benchmark the numerical subduction modeling using a finite element package, COMSOL $Multiphysics^{(R)}$ and the results are consistent with the previously reported benchmark results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.161-172
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• 2018

This paper proposed the robot vision control method to track a moving rigid body target using the vision system model that can actively control camera parameters even if the relative position between the camera and the robot and the focal length and posture of the camera change. The proposed robotic vision control scheme uses a batch method that uses all the vision data acquired from each moving point of the robot. To process all acquired data, this robot vision control scheme is divided into two cases. One is to give an equal weight for all acquired data, the other is to give weighting for the recent data acquired near the target. Finally, using the two proposed robot vision control schemes, experiments were performed to estimate the positions of a moving rigid body target whose spatial positions are unknown but only the vision data values are known. The efficiency of each control scheme is evaluated by comparing the accuracy through the experimental results of each control scheme.