• Journal of Welding and Joining
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• v.24 no.4
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• pp.32-38
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• 2006

The objective of present research works is to investigate the effects of process parameters, including the power of laser, cutting speed, material thickness, and the edge angle, on the melted area in the sharp edge of the cut material fur the case of cutting of a low carbon steel sheet using high-power CW Nd:YAG laser. In order to investigate the influence of edge angle and size of loop on the melted area in the sharp edge, angular cutting tests and loop cutting tests have been carried out. From the results of angular cutting tests, the relationship between the edge angle and the melted area has been obtained. The results of the experiments have been shown that the melted area is rapidly reduced from $120^{\circ}$ of the edge angle and the melted area is nearly zero at $150^{\circ}$ of the edge angle. Through the results of loop cutting experiments, the relationship between the cutting angle on the melted area in the edge according to the size of loop have been obtained. In addition, it has been shown that a proper size of loop is nearly 3 mm as the corner angle is greater than $90^{\circ}$ and 5 mm as the comer angle is less than $90^{\circ}$. The results of above experiments will be reflected on the knowledge base to generate optimal cutting path of the laser.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.571-572
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• 2017

The blockchain technology that implements electronic money uses decentralized computing and all transactions in a blockchain are open to everyone. This technique seems to guarantee anonymity by performing the transaction on the address instead of the user, but by using direction acyclic graph based on the transaction graph, the privacy problem is caused by tracking the addresses. In this paper, we analyze various techniques for centralized processing which makes it difficult to find the relevance on the graph in order to protect the privacy in the block chain technology. We also analyze the techniques of anonymizing in a distributed way to enhance privacy. Using the zero knowledge proof scheme guarantees full distributed anonymity but requires more computation and storage space, and various techniques to make this efficient are proposed. In this paper, we propose a privacy protection scheme of blockchain technology to integrate existing privacy protection techniques into a blockchain technology and perform it more efficiently with a centralized or decentralized technique.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.1
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• pp.33-42
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• 2002

We present a systematic way to armor a zero-knowledge interactive proof based identification scheme that has badly chosen keys. Keys are sometimes mistakenly chosen to be weak(neither random nor long), and a weak key is often preferred to a strong key so that it might be easy for human to remember. Weak keys severely degrade the security of ZKIP based identification schemes. We show using off-line guessing attack how the weak key threats the security of ZlKIP based identification schemes. For the proper usage of ZKIP, we introduce a specialized form of ZKIP, which has a secret coin-tossing stage. Using the secret coin tossing, a secure framework is proposed for ZKIP based identification schemes with weak key in the ideal cipher model. The framework is very useful in password based authentication and key exchange protocol

• Clinical and Experimental Reproductive Medicine
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• v.49 no.1
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• pp.16-25
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• 2022

In mammalian species, females are born with a number of oocytes exceeding what they release via ovulation. In humans, an average girl is born with over a thousand times more oocytes than she will ovulate in her lifetime. The reason for having such an excessive number of oocytes in a neonatal female ovary is currently unknown. However, it is well established that the oocyte number decreases throughout the entire lifetime until the ovary loses them all. In this review, data published in the past 80 years were used to assess the current knowledge regarding the changing number of oocytes in humans and mice, as well as the reported factors that contribute to the decline of oocyte numbers. Briefly, a collective estimation indicates that an average girl is born with approximately 600,000 oocytes, which is 2,000 times more than the number of oocytes that she will ovulate in her lifetime. The oocyte number begins to decrease immediately after birth and is reduced to half of the initial number by puberty and almost zero by age 50 years. Multiple factors that are either intrinsic or extrinsic to the ovary contribute to the decline of the oocyte number. The inflammation caused by the ovulatory luteinizing hormone surge is discussed as a potential contributing factor to the decline of the oocyte pool during the reproductive lifespan.

• Journal of Veterinary Science
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• v.22 no.5
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• pp.47.1-47.10
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• 2021

Background: Due to multiple similarities in the structure and physiology of human and pig skin, the pig model is extremely useful for biological drug testing after subcutaneous administration. Knowledge of the differences between subcutaneous injection sites could have a significant impact on the absorption phase and pharmacokinetic profiles of biological drugs. Objectives: This study aimed to analyze the impact of administration site on pharmacokinetics and selected biochemical and hematological parameters after a single subcutaneous administration of ustekinumab in pigs. Drug concentrations in blood plasma were analyzed by enzyme-linked immunosorbent assay. Pharmacokinetic analyses were performed based on raw data using Phoenix WinNonlin 8.1 software and ThothPro v 4.1. Methods: The study included 12 healthy, female, large white piglets. Each group received a single dose of ustekinumab given as a 1 mg/kg subcutaneous injection into the internal part of the inguinal fold or the external part of the inguinal fold. Results: The differences in absorption rate between the internal and external parts of the inguinal fold were not significant. However, the time of maximal concentration, clearance, area under the curve calculated between zero and mean residence time and mean residence time between groups were substantially different (p > 0.05). The relative bioavailability after administration of ustekinumab into the external part of the inguinal fold was 40.36% lower than after administration of ustekinumab into the internal part of the inguinal fold. Conclusions: Healthy breeding pigs are a relevant model to study the pharmacokinetic profile of subcutaneously administered ustekinumab.

• Smart Structures and Systems
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• v.31 no.5
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• pp.485-500
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• 2023

Machine learning-based structural health monitoring (ML-based SHM) methods are researched extensively in the recent decade due to the availability of advanced information and sensing technology. ML methods are well-known for their pattern recognition capability for complex problems. However, the main obstacle of ML-based SHM is that it often requires pre-collected historical data for model training. In most actual scenarios, damage presence can be detected using the unsupervised learning method through anomaly detection, but to further identify the damage types would require prior knowledge or historical events as references. This creates the cold-start problem, especially for new and unobserved structures. Modal-based methods identify damages based on the changes in the structural global properties but often require dense measurements for accurate results. Therefore, a two-stage hybrid modal-machine learning damage detection scheme is proposed. The first stage detects damage presence using Principal Component Analysis-Frequency Response Function (PCA-FRF) in an unsupervised manner, whereas the second stage further identifies the damage. To solve the cold-start problem, mode shape assessment using the first mode is initiated when no trained model is available yet in the second stage. The damage identified by the modal-based method would be stored for future training. This work highlights the performance of the scheme in alleviating the cold-start issue as it transitions through different phases, starting from zero damage sample available. Results showed that single and multiple damages can be identified at an acceptable accuracy level even when training samples are limited.

• Journal of Nutrition and Health
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• v.42 no.3
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• pp.256-267
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• 2009

This study was conducted to investigate nutritional knowledge related to breakfast and dietary behavior of elementary school students by gender and skipping breakfast. The subjects of this study were the 6th grade elementary school students (Total 237; 119 males and 118 females) in Daejeon. The group who ate breakfast six to seven times per week was 58.6%; The group who ate breakfast zero to five times per week was 41.4%. Most of subjects' families (84.4%) were 'nuclear family' and 63.8% of mothers held jobs. There was a significant difference between family income and skipping breakfast. As for the type of breakfast, 79.0% of the male students and 81.4% of female students answered 'cooked rice' and the reasons for skipping breakfast were 'no appetite' followed by 'not enough time', 'over sleeping'. In the eating breakfast group, frequency of having breakfast with family was higher compared to the skipping breakfast group. Total scores of nutritional knowledge related to breakfast in the female students were significantly higher than those of the male students. Also significant differences were found on such questions as 'the relation between eating breakfast and body weight control' and 'importance of breakfast' by skipping breakfast. The dietary behavior scores of the group who ate breakfast were higher than those of the group who skipped breakfast. Therefore, a need exists to develop and distribute a simple breakfast menu that contains Korean-style food and can be more appetizing and appealing to Korean elementary school students. Also it is necessary to develop a systemic awareness program that emphasize the importance of breakfast and the harmfulness of skipping breakfast.

• The Korean Journal of Applied Statistics
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• v.22 no.2
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• pp.329-340
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• 2009

For complex diseases such as diabetes, hypertension, it is believed that model-free methods might work better because they do not require a precise knowledge of the mode of inheritance controlling the disease trait. This is done by estimating the sharing probabilities that a pair shares zero, one, or two alleles identical by descent(IBD) and has some specific branches of test procedure, i.e., the mean test, the proportion test, and the minmax test. Among them, the minmax test is known to be more robust than others regardless of genetic mode of inheritance in current use. In this study, we compared the power of the methods which are based on minmax test and considering weighting schemes for sib-pairs to analyze sibship data. In simulation result, we found that the method based on Suarez' was more powerful than any others without respect to marker allele frequency, genetic mode of inheritance, sibship size. Also, The power of both Suarez- and Hodge-based methods was higher when marker allele frequency and sibship size were higher, and this result was remarkable in dominant mode of inheritance especially.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.459-468
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• 2001

The Average Coordinate Referenee System (ACRS) method is developed to reduce experimental errors in human locomotion analysis. Experimentally measured kinematic data is used to conduct analysis in human modeling, and the model accuracy is directly related to the accuracy of the data. However. the accuracy is questionable due to skin movement. deformation of skeletal structure while in motion and limitations of commercial motion analysis system . In this study. the ACRS method is applied to an optically-tracked segment marker system. although it can be applied to many of the others as well. In the ACRS method, each marker can be treated independently. as the origin of a local coordinate system for its body segment. Errors, inherent in the experimental process. result in different values for the recovered Euler angles at each origin. By employing knowledge of an initial, calibrated segment reference frame, the Euler angles at each marker location can be averaged. minimizing the effect of the skin extension and rotation. Using the developed ACRS methodology the error is reduced when compared to the general Euler angle method commonly applied in motion analysis. If there is no error exist in the experimental gait data. the separation and Penetration distance of the femoraltibial joint using absolute coordinate system is supposed to be zero during one gait cycle. The separation and Penetration distance was ranged up to 18 mm using general Euler angle method and 12 mm using the developed ACRS.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.323-328
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• 2004

The development of group-specific tissue probability maps (TPM) provides a priori knowledge for better result of cerebral tissue classification with regard to the inter-ethnic differences of inter-subject variability. We present sequential procedures of group-specific TPM and evaluate the age effects in the structural differences of TPM. We investigated 100 healthy volunteers with high resolution MRI scalming. The subjects were classified into young (60, 25.92+4.58) and old groups (40, 58.83${\pm}$8.10) according to the age. To avoid any bias from random selected single subject and improve registration robustness, average atlas as target for TPM was constructed from skull-stripped whole data using linear and nonlinear registration of AIR. Each subject was segmented into binary images of gray matter, white matter, and cerebrospinal fluid using fuzzy clustering and normalized into the space of average atlas. The probability images were the means of these binary images, and contained values in the range of zero to one. A TPM of a given tissue is a spatial probability distribution representing a certain subject population. In the spatial distribution of tissue probability according to the threshold of probability, the old group exhibited enlarged ventricles and overall GM atrophy as age-specific changes, compared to the young group. Our results are generally consistent with the few published studies on age differences in the brain morphology. The more similar the morphology of the subject is to the average of the population represented by the TPM, the better the entire classification procedure should work. Therefore, we suggest that group-specific TPM should be used as a priori information for the cerebral tissue classification.