• Journal of the Korean Magnetics Society
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• v.19 no.3
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• pp.106-112
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• 2009

$Ni_{1-x}Mg_xFe_2O_4$ ferrite system was studied by using X-ray diffraction and $M{\ddot{o}}ssbauer$ spectroscopy. The samples were prepared by ceramic sintering method with Mg content x. The X-ray diffraction patterns of samples show phase of cubic spinel structure. There are no remarkable changes of lattice constants in $Ni_{1-x}Mg_xFe_2O_4$ ferrite system. The $M{\ddot{o}}ssbauer$ spectra were consisted of two sets of six lines, respectively, corresponding to $Fe^{3+}$ at tetrahedral and octahedral sites. The magnetic hyperfine field of samples was decreased as increasing Mg contents x in both sites and it was shown Yafet-Kittel magnetic structure. $NiFe_2O_4$ was shown complete inverse spinel, but $NiFe_2O_4$ was shown partial inverse spinel which absorption area ratio (oct/tet) was 1.449 in $M{\ddot{o}}ssbauer$ spectrum.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.89-98
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• 2005

Fingerprint segmentation and ridge orientation estimation algorithms with images from a mobile camera are proposed. The fingerprint images from a mobile camera are quite different from those from conventional sensor, called touch based sensor such as optical, capacitive, and thermal. For example, the images from a mobile camera are colored and the backgrounds or non-finger regions are very erratic depending on how the image capture time and place. Also the contrast between ridge and valley of a mobile camera image are lower than that of touch based sensor image. To segment fingerprint region, we first detect the initial region using color information and texture information. The LUT (Look Up Table) is used to model the color distribution of fingerprint images using manually segmented images and frequency information is extracted to discriminate between in focused fingerprint regions and out of focused background regions. With the detected initial region, the region growing algerian is executed to segment final fingerprint region. In fingerprint orientation estimation, the problem of gradient based method is very sensitive to outlier that occurred by scar and camera noise. To solve this problem, we propose a robust regression method that removes the outlier iteratively and effectively. In the experiments, we evaluated the result of the proposed fingerprint segmentation algerian using 600 manually segmented images and compared the orientation algorithms in terms of recognition accuracy.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4
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• pp.380-386
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• 2002

Conventional post-processing as like confidence measure (CM) proposed by Rahim calculates phones' CM using the likelihood between phoneme model and anti-model, and then word's CM is obtained by averaging phone-level CMs[1]. In conventional method, CMs of some specific keywords are tory low and they are usually rejected. The reason is that statistics of phone-level CMs are not consistent. In other words, phone-level CMs have different probability density functions (pdf) for each phone, especially sri-phone. To overcome this problem, in this paper, we propose normalized confidence measure. Our approach is to transform CM pdf of each tri-phone to the same pdf under the assumption that CM pdfs are Gaussian. For evaluating our method we use common keyword spotting system. In that system context-dependent HMM models are used for modeling keyword utterance and contort-independent HMM models are applied to non-keyword utterance. The experiment results show that the proposed NCM reduced FAR (false alarm rate) from 0.44 to 0.33 FA/KW/HR (false alarm/keyword/hour) when MDR is about 8%. It achieves 25% improvement of FAR.

• Journal of Life Science
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• v.17 no.10
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• pp.1441-1446
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• 2007

This study was conducted to establish the individual identification system and to estimate the genetic characteristic of Jeju native horse (JNH) using 13 microsatellite markers located on different horse autosomes. The markers were genotyped on 191 animals from five horse breeds including Jeju native horse (JNH). In total, 138 alleles were detected from the genotypes of 13 microsatellite markers. The average heterozygosities ranged from 0.317 to 0.902 and the polymorphic information content (PIC) ranged from 0.498 to 0.799 in JNH. We found that there were significant differences in allele frequencies in JNH when compared with other horse breeds. In ATH4 marker, there were specific allele frequence pattern that some of allele only found in JNH, Mongolian horse (MONG) and Jeju racing horse (JRH). The calculated cumulative power of discrimination (CPD) was 99.9% when nine microsatellite loci were used for analysis in the individual identification system. Also, the matching probability that two unrelated animals would show the same genotypes, was estimated to be $0.60{\times}10^{-10}$. Therefore, in the nine markers used in this study can be used for individual identification in the Jeju native horse population.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.195-203
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• 2016

Concrete slab track was applied to the Gyeoungbu High Speed Railroad step 2 and the Honam High Speed Railroad. Concrete slab track incurs higher construction cost and lower maintenance cost than existing gravel track. For these reasons, the use of concrete slab track has increased in Korea. The biggest problem in the use of concrete slab track is repairing damage from settlement that can occur while trains are in service. High speed railroad design standards require allowable residual settlement of concrete slab track of less than 25mm. In order to satisfy the requirement of long term stability of concrete slab track, it is necessary to manage the secondary compression settlement within the allowable residual settlement. This study is to evaluate the secondary compression settlement with the variation of the secondary compression index, thickness of soft ground, and concrete slab track life. Statistical analysis is performed to determine the probability of distribution of areas where serious problems will be caused after the concrete slab track is constructed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.98-106
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• 2006

In order to provide a realtime transmission over a wireless LAM, we here present a new jamming based retransmission mechanism. In a legacy wireless LAN system, all stations use the binary exponential backoff algorithm to avoid collisions among frames. It is well known that the backoff algorithm causes more collisions as the numbers of active stations increases. This makes transmission of real time traffic hard. In the proposed scheme, when each station senses collisions, it promptly allows to send a jamming signal during a unique jamming window period which is determined by its own channel access count database(CACDB). This jamming windows is chosen not to be overlapped each other by using of CACDB, and thus channel access of another station is prevented. Hereafter the station gets the ownership of the medium when the wireless medium becomes idle after sending the jamming signal and sensing carrier, and then sends frame in medium. In our proposal, repeating collisions is never happened. We here assume that real time traffic use a frame of fixed length in order to make the time for receiving its ACK frame same. Comparing the proposed jamming-based retransmission scheme with the the 802.11 and 802.11e MAC by simulation. one can find that the proposed scheme have advantages in terms of delay, average backoff time, and average number of collisions per frame. One can find that the proposed scheme might be practically applicable to several applications of realtime traffic transmission in wireless LAN systems.

• Journal of Navigation and Port Research
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• v.33 no.3
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• pp.181-191
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• 2009

In general, seafarer's human error is considered to be the preponderant muse for the majority of maritime transportation accidents in a merchant ship. The implementation techniques for Human Error Model (HEM) to assess possible accident risk by deck officers including captain, chief officer, second mate and third mate are described in this study. The scope of this work is focused to 642 deck officers in the ship management company with 130 vessels. At first, HEM can be constructed through the statistical analysis and expert's brainstorming process with human data to 642 deck officers. Then the variables $\upsilon$ for the human factors, the evaluation level EP($\upsilon$) for $\upsilon$, the weight $\alpha$ of $\upsilon$, and the title weight $\beta$ of each deck officers can be decided. In addition, through the analysis of ship's accident history, the accident causation ratios by human error ${\gamma}_H$ and by external error ${\gamma}_B$ can be found as 0.517(51.7%) and 0.483(48.3%), respectively. The correlation coefficients to $\upsilon$ are also shown significant for a 95% confidence interval (p < 0.05) for each coefficient. And the validity of HEM is also surveyed by the analysis of normal probability distribution of risk level RL to each deck officer.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.3
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• pp.103-113
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• 2018

Tide-surge characteristics of the West/South domestic coasts were analyzed with a tool of EST (empirical simulation technique). As a result, stations of Incheon, Gunsan, Mokpo and Busan are categorized as tide-dominant coasts, while Yeosu, Tongyoung and Busan are as surge-dominant coasts. In the tide-dominant coasts, extreme sea level of less than 50-yr frequency is formed without typhoon-surge, while only 10-yr extreme sea level is formed in the surge-dominant coasts. As the results of casual condition of extreme sea level formation considering the relative degree of surge on tide, the regional characteristics were detected also. Three methods for estimating the design tide level were compared. The AHHW method shows an unrealistic outcomes of the concern of over estimate design. Furthermore, the probability distribution function method has been concerned as causing missing data if a huge typhoon occurs in a neap tide or a low tide. To cope with these drawbacks, the applicability of the EST method is proved to be suitable especially in tide-dominant coasts.

• 대한방사선치료학회:학술대회논문집
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• 2005.06a
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• pp.23-26
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• 2005

Introduction: To evaluate whether modified MUPIT applicator can effectively eradicate recurrent tumor in uterine cervix cancer and reduce rectal complication after complete radiation treatment. Methods and Materials: Modified MUPIT applicator basically consists of an acrylic cylinder with flexible brain applicator , an acrylic template with a predrilled array of holes that serve as guides for interstitial needles and interstitial needles. CT scan was performed to determine tumor volume and the position of interstitial needles. Modified MUPIT applicator was applied to patient in operation room and the accuracy for position of interstitial needles in tumor volume was confirmed by CTscan. Brachytherapy was delivered using modified MUPIT applicator and RALS (192-Ir HDR) after calculated computer planning by orthogonal film. The daily dose was 600cGy and the total dose was delivered 3000cGy in tumor volume by BID. Rectal dose was measured by TLD at 5 points so that evaluated the risk of rectal complication. Result: The application of modified MUPIT applicator improved dramatically dose distributions in tumor volume and follow-up of 3 month for this patient was clinically partial response without normal tissue complication, Rectal dose was measured 34.1cGy, 57.1cGy, 103.8cGy, 162.7cGy, 165.7cGy at each points, especially the rectal dose including previous EBRT and ICR was 34.1cGy, 57.1cGy Conclusion: Patients with locally recurrent tumor in uterine cervix cancer treated with modified MIUPIT applicator can expect reasonable rates of local control. The advantages of the system are the fixed geometry Provided by the template and cylinders, and improved dose distributions in irregular tumor volume without rectal complication

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.3
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• pp.306-311
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• 2016

Software reliability in the software development process is an important issue. Infinite failure NHPP software reliability models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, reliability software cost model considering logarithmic and exponential fault detection rate based on observations from the process of software product testing was studied. Adding new fault probability using the Goel-Okumoto model that is widely used in the field of reliability problems presented. When correcting or modifying the software, finite failure non-homogeneous Poisson process model. For analysis of software reliability model considering the time-dependent fault detection rate, the parameters estimation using maximum likelihood estimation of inter-failure time data was made. The logarithmic and exponential fault detection model is also efficient in terms of reliability because it (the coefficient of determination is 80% or more) in the field of the conventional model can be used as an alternative could be confirmed. From this paper, the software developers have to consider life distribution by prior knowledge of the software to identify failure modes which can be able to help.