• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.849-858
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• 2023

Investigating disaster sites such as earthquakes and landslides involves significant risks due to potential secondary disasters like facility collapse. In situations where direct access is challenging, there is a need to develop methods for safely acquiring high-precision 3D disaster information using light detection and ranging (LiDAR) equipped drone survey systems. In this study, the feasibility of using drone LiDAR in disaster scenarios was examined, focusing on the collapse accident at Jeongja Bridge in Bundang-gu, Seongnam City, in April 2023. High-density point clouds for the accident bridge were collected, and the bridge's 3D terrain information was reconstructed and compared to the measurement performance of 10 ground control points. The results showed horizontal and vertical root mean square error values of 0.032 m and 0.055 m, respectively. Additionally, when compared to a point cloud generated using ground LiDAR for the same target area, a vertical difference of approximately 0.08 m was observed, but overall shapes showed minimal discrepancies. Moreover, in terms of overall data acquisition and processing time, drone LiDAR was found to be more efficient than ground LiDAR. Therefore, the use of drone LiDAR in disaster sites with significant risks allows for safe and rapid onsite investigations.

• Journal of Sensor Science and Technology
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• v.7 no.6
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• pp.418-425
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• 1998

Stereo cameras are the most widely used sensing systems for automated machines including robots to interact with their three-dimensional(3D) working environments. The position of a target point in the 3D world coordinates can be measured by the use of stereo cameras and the camera calibration is an important preliminary step for the task. Existing camera calibration techniques can be classified into two large categories - linear and nonlinear techniques. While linear techniques are simple but somewhat inaccurate, the nonlinear ones require a modeling process to compensate for the lens distortion and a rather complicated procedure to solve the nonlinear equations. In this paper, a method employing a neural network for the calibration problem is described for tackling the problems arisen when existing techniques are applied and the results are reported. Particularly, it is shown experimentally that by utilizing the function approximation capability of multi-layer neural networks trained by the back-propagation(BP) algorithm to learn the error pattern of a linear technique, the measurement accuracy can be simply and efficiently increased.

• Journal of Korea Water Resources Association
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• v.33 no.5
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• pp.611-622
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• 2000

In this study, MODFLOW model is used to analyze the groundwater flow system of Seoguipo area in Cheju island, The final parameters of permeability coefficient and storage coefficient of target area can be obtained by trial and error method using the measured data of pumping rate as initial values. And it is found that the applicability for groundwater flow system is reflected well from the simulation result of the model. Seoguipo area spring water is thought to appear by relatively stable groundwater recharge below EL. 400m according to head distribution through the analysis of observed data considering topographic and geological characteristics, Lee's study(996), and the simulation result. Also it is known that point II, III, and VI show relatively large velocity vectors, and groundwater flows through the movement path which is distributed in various directions of I, II, III, IV, V, VI, and VIl form the result of velocity vector analysis using head distribution result values to analyze the groundwater flow path under unsteady flow condition.dition.

• Gut and Liver
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• v.12 no.6
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• pp.641-647
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• 2018

Background/Aims: Helicobacter pylori eradication rates are decreasing because of increases in clarithromycin resistance. Thus, finding an easy and accurate method of detecting clarithromycin resistance is important. Methods: We evaluated 70 H. pylori isolates from Korean patients. Dual-labeled peptide nucleic acid (PNA) probes were designed to detect resistance associated with point mutations in 23S ribosomal ribonucleic acid gene domain V (A2142G, A2143G, and T2182C). Data were analyzed by probe-based fluorescence melting curve analysis based on probe-target dissociation temperatures and compared with Sanger sequencing. Results: Among 70 H. pylori isolates, 0, 16, and 58 isolates contained A2142G, A2143G, and T2182C mutations, respectively. PNA probe-based analysis exhibited 100.0% positive predictive values for A2142G and A2143G and a 98.3% positive predictive value for T2182C. PNA probe-based analysis results correlated with 98.6% of Sanger sequencing results (${\kappa}$-value=0.990; standard error, 0.010). Conclusions: H. pylori clarithromycin resistance can be easily and accurately assessed by dual-labeled PNA probe-based melting curve analysis if probes are used based on the appropriate resistance-related mutations. This method is fast, simple, accurate, and adaptable for clinical samples. It may help clinicians choose a precise eradication regimen.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.3
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• pp.1-15
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• 2021

Objective: The purpose of this study was to examine the differences in joint position sense (JPS), force sense (FS), and performance level of the upper extremities according to the injury and pain experiences of Korean elite archers. Methods: A total of 15 subjects were briefed about the purpose of this study and agreed to participate voluntarily. JPS was evaluated using the laser-point attached to the wrist while aiming at the target. The difference when relocating while aiming was used as JPS factor. FS was evaluated using load cell through reproduces same muscle strength. Fear-Avoidance Beliefs Questionnaire (FABQ) was used to evaluate psychosocial factors, Kerlan-Jobe Orthopedic Clinic overhead athlete scores (KJOC) and numerical rating scale (NRS) was used to evaluate pain. and performance was evaluated by tournament match score. Results: There is a strong correlation between the current pain and KJOC. Moreover, moderate correlation between KJOC and FABQ also current pain and both upper trapezius and lower trapezius in elite archers. The mean (SD) between groups based on current pain display relatively large margin in force sense than without pain group. The result presents that there is a significant difference in performance and pain. There is a significant difference in the force sense of the upper and lower trapezius and pain. Conclusions: Result present there is a significant difference in functional level in the average comparison between groups according to the presence of absence of current pain. There is a significant difference in the force sense of the upper trapezius as well as lower trapezius and without pain group present a relatively low joint position sense error compared to the groups.

• Progress in Medical Physics
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• v.13 no.1
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• pp.9-14
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• 2002

We invented the newly developed Fractionated Stereotactic Radiotherapy(F.S.R.T) system using combined techniques of couch mounting and pedestal mounting system. Head fixation frame consists of a milled alluminium alloy(duralumin) and is placed to the couch. This frame immobilized patient head using the dental bite, 3.2 mm frontal and occipital thermoplastic mask. To evaluate the coordinate of target isocenter, Brown-Revert-Walls C.T localizer can be attached to this frame. And also, we developed the frame mounting system by developing the modification of pedestal mounting system. This system is fixed to couch floor and can be used to evaluate the isocenteric accuracy of gantry, couch and collimator in Q.A procedure. In order to measure the relocation accuracy, the acrylic phantom and the accurate pointers have been made. The repositioning of the targets in the phantom were estimated by comparing C.T coordinates and E.C.L portal films taken with anterior-posterior and right-left direction. From the results of experiments, the average distance errors between the target isocenter and its mean position were 0.71$\pm$0.19 for lateral, 0.45$\pm$0.15 for inferior-superior, 0.63$\pm$0.18 for anterior-posterior. And the maximum distance error was less than 1.3 mm. The new head fixation frame and frame mounting system were non-invasive, accurately relocatable, easy to use, very light and well tolerable by the results of phantom tests. The major advantage of using this frame mounting system is complete access to any point in the Patients cranium especially posterior direction

• Journal of Korea Multimedia Society
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• v.16 no.3
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• pp.318-329
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• 2013

This paper proposes a DNA watermarking method for the privacy protection and the prevention of illegal copy. The proposed method allocates codons to random circular angles by using random mapping table and selects triplet codons for embedding target with the help of the Lipschitz regularity value of local modulus maxima of codon circular angles. Then the watermark is embedded into circular angles of triplet codons without changing the codes of amino acids in a DNA. The length and location of target triplet codons depend on the random mapping table for 64 codons that includes start and stop codons. This table is used as the watermark key and can be applied on any codon sequence regardless of the length of sequence. If this table is unknown, it is very difficult to detect the length and location of them for extracting the watermark. We evaluated our method and DNA-crypt watermarking of Heider method on the condition of similar capacity. From evaluation results, we verified that our method has lower base changing rate than DNA-crypt and has lower bit error rate on point mutation and insertions/deletions than DNA-crypt. Furthermore, we verified that the entropy of random mapping table and the locaton of triplet codons is high, meaning that the watermark security has high level.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.23-32
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• 2020

The compression sensing technology, CAFB, was developed to obtain the raw signal of the target structure by compressing it into a signal of the intended frequency range. At this point, for compression sensing, the CAFB can be optimized for various reference signals depending on the desired frequency range of the target structure. In addition, optimized CAFB should be able to efficiently compress the effective structural answers of the target structure even in sudden/dangerous conditions such as earthquakes. In this paper, the targeted frequency range for efficient structural integrity monitoring of relatively flexible structures was set below 10Hz, and the optimization method of CAFB for this purpose and the seismic response performance of CAFB in seismic conditions were evaluated experimentally. To this end, in this paper, CAFB was first optimized using Kobe seismic waveform, and embedded it in its own wireless IDAQ system. In addition, seismic response tests were conducted on two span bridges using Kobe seismic waveform. Finally, using an IDAQ system with built-in CAFB, the seismic response of the two-span bridge was wirelessly obtained, and the compression signal obtained was cross-referenced with the raw signal. From the results of the experiment, the compression signal showed excellent response performance and data compression effects in relation to the raw signal, and CAFB was able to effectively compress and sensitize the effective structural response of the structure even in seismic situations. Finally, in this paper, the optimization method of CAFB was presented to suit the intended frequency range (less than 10Hz), and CAFB proved to be an economical and efficient data compression sensing technology for instrumentation-monitoring of seismic conditions.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.39-48
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• 2007

The stimulus of accommodation A, the stimulus of convergence C and the prism diopter ${\Delta}$ are reviewed and redefined more obviously. How the A and C are managed in the practice are reviewed and summarized. As a result, the common practical process of the binocular vision findings is most suitable in the case of the $l_c=26.67mm$, where the near distance is measured from the test lens to the near target and its value is 40 cm and the average of the P.D equal to 64 mm. The $l_c$ is the distance between the test lens and the center of rotation. Those values were used at calculating the various values in this paper. The error of the stimulus of accommodation values which are evaluated by the practically used formula (5) are calculated. Where the distance between lens and the principle point of eye is 15.07 mm ($=l_H$). The incremental stimulus of convergence values P' caused by the addition prism $P_m$ are evaluated by the recursion computation method. The P' are varied with the $P_m$, the distance $p_c$ between the prism and the center of rotation, the initial convergence value (or inverse target distance) $C_o$ and the refractive index n of the prism material. The recursion computation method and the other formulas are described in detail. In this paper n=1.7 is used. The two factors by which the P' is increased are exist. The one which is major is the property by which the values of convergence whose unit is ${\Delta}$ are not added in the generally way. The other is the that the actual power of the prism is varied with the angle of incidence light. And the P' is decreased remarkably by an increase in the $p_c$ and $C_o$. The $P^{\prime}/P_m$ are calculated and graphed which are varied with the $p_c$ and $C_o$, where the $P_m=20{\Delta}$, P.D=64 mm and n=1.7. The index n dependence of the $P^{\prime}/P_m$ is negligible (refer to fig. 6). The $p_c$ are evaluated at which the P' equal to the $P_m$ for various $P_m$ (refer to table 1). The actual values of the stimulus of convergence and accommodation which are manipulated simply in the practice are calculated. Two graphical forms are suggested. The one is like as the commonly used one. But the stimulus of convergence and of accommodation values in the practice are positioned at the exact positions when the graphic is made (refer to fig. 9). The other is the form that the incremental stimulus of convergence values caused by the addition prisms are represented at actual positions (refer to fig. 11).

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.6
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• pp.109-115
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• 2014

Sales of online games companies that began from the small and medium-sized ventures, have grown to billions or hundreds of million dollars to target the global market. The issues related with industrial policies and regulations for game industry gain attentions. In particular, the Korean government has strengthened the relevant regulations of the webboard game service across many departments within the government such as Media Rating Commission, Game Products Administrative Committee, Ministry of Culture, Tourism and Sports, and Ministry of Female and Family. In this study, we analyze the effects of government regulation on webboard games using a VECM(Vector Error Correction Model). We have acquired the Gametrix time-series data during a year since July 2013. Having the co-integration estimated in the analysis process, we attempt to identify the long-term equilibrium relationship within webboard game industry and predict use time in near future. The results show that the use time has decreased to a third to a fourth comparing to the initial value at the beginning point in 2013. Two representative webboard games are exposed to the significant risks to have less or no use time. Additionally, we discuss the issues of the overall game industry influenced by the changes of webboard games.