• Journal of the Korean institute of surface engineering
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• v.54 no.5
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• pp.278-284
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• 2021

Corrosion of steel plate is common phenomenon which results in the gradual destruction caused by a wide variety of environments. Corrosion monitoring is the tracking of the degradation progress for a long period of time. Corrosion on steel plate appears as a discoloration and any irregularities on the surface. In this study, we developed a quantitative evaluation method of the rust formed on steel plate by using k-means clustering from the corroded area in a given image. The k-means clustering for automated corrosion detection was based on the GrabCut segmentation and Gaussian mixture model(GMM). Image color of the corroded surface at cut-edge area was analyzed quantitatively based on HSV(Hue, Saturation, Value) color space.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.145-154
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• 2024

In order to operate predictive models utilizing administrative big data, it is crucial to consider policy changes and the characteristics of highly volatile data. Considering this scenario, this study proposes the Cut-off Voting Classifier (CVC) algorithm. This proposed algorithm prevents a sharp decline in accuracy by utilizing multiple weak classifiers. The study validates the proposed algorithm's performance through experiments. The performance evaluation demonstrates the ability to maintain stable prediction rates even in situations with a sharp decline in predictive model accuracy.

• Journal of Korean Foot and Ankle Society
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• v.19 no.2
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• pp.51-57
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• 2015

Purpose: Minimal incision distal metatarsal osteotomy (MIDMO) is known to be an effective surgical procedure for mild to moderate hallux valgus. However, the result of MIDMO on moderate to severe hallux valgus is controversial; therefore, we investigated the radiological and clinical results of MIDMO on moderate to severe hallux valgus. Materials and Methods: We reviewed 51 feet (48 patients) with moderate to severe hallux valgus. The mean age was 67.0 years and the mean follow-up period was 32.2 months. Radiological data of hallux valgus angle, first intermetatarsal angle, and distal metatarsal articular angle on plain radiographs were analyzed. Recurrence, union, lateral translation of distal fragment and angulation were also analyzed. The clinical data were obtained using American Orthopaedic Foot and Ankle Society (AOFAS) score of preoperation and last follow-up. Receiver operating characteristic (ROC) curve was used to determine a cut-off value. Results: The mean hallux valgus angle measured at preoperation was $37.7^{\circ}$ and $15.9^{\circ}$ at last follow-up. The mean first intermetatarsal angle of preoperation and last follow-up were $15.2^{\circ}$ and $8.3^{\circ}$. The mean distal metatarsal articular angle changed from $12.6^{\circ}$ at preoperation to $7.8^{\circ}$ at last follow-up. Preoperative hallux valgus angle (p=0.0051) and distal metatarsal articular angle (p=0.0078) were statistically significant factors affecting postoperative AOFAS score. Cut-off value of each was $37^{\circ}$ and 13o, respectively. Lateral translation of distal fragment in 5 recurrent cases was 23.0% compared to 45.3% of 46 non-recurrent cases. The result was statistically significant and the cut-off value was 38%. Conclusion: Sufficient lateral translation over 38% in MIDMO on moderate to severe hallux valgus patients with preoperative hallux valgus angle under $37^{\circ}$ and distal metatarsal articular angle under $13^{\circ}$ can lead to good clinical results without recurrence.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.723-730
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• 2018

Objective : The aim of the present study was to identify whether the deformity angular ratio (DAR) influences the occurrence of complications after posterior vertebral column resection (PVCR) and to establish the DAR cut-off value. Methods : Thirty-six consecutive patients undergoing PVCR from December 2010 to October 2016 were reviewed. The relationships between the total, sagittal, and coronal DAR and complications were assessed using receiver operator characteristics curves. The patients were divided into two groups according to a reference value based on the cut-off value of DAR. Demographic, surgical, radiological, and clinical outcomes were compared between the groups. Results : There were no significant differences in the patient demographic and surgical data between the groups. The cut-off values for the total DAR (T-DAR) and the sagittal DAR (S-DAR) were 20.2 and 16.4, respectively (p=0.018 and 0.010). Both values were significantly associated with complications (p=0.016 and 0.005). In the higher T-DAR group, total complications (12 vs. 21, p=0.042) and late-onset complications (3 vs. 9, p=0.036) were significantly correlated with the T-DAR. The number of patients experiencing complications (9 vs. 11, p=0.029) and the total number of complications (13 vs. 20, p=0.015) were significantly correlated with the S-DAR. Worsening intraoperative neurophysiologic monitoring was more frequent in the higher T-DAR group (2 vs. 4) than in the higher S-DAR group (3 vs. 3). There was no difference in neurological deterioration between the groups after surgery. Conclusion : Both the T-DAR and the S-DAR are risk factors for complications after PVCR. Those who had a T-DAR >20.2 or S-DAR >16.4 experienced a higher rate of complications after PVCR.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.2
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• pp.115-124
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• 2010

Objective: To testify whether the increased peripheral blood natural killer (pbNK) cells fraction and their cytolytic activity could coincide with patient's history of recurrent spontaneous abortion (RSA) and to evaluate these factors are can be valuable diagnostic markers in RSA. Methods: Women with a history of RSA comprised the patient group (n=35). Normal fertile women, who were experienced at least one healthy term birth without history of infertility or recurrent miscarriage, were included as the healthy control group (n=15). The pbNK cells of $CD3^-/CD56^+/CD16^+$ and their cytolytic activities against K562 cells were measured by flow cytometry and the values were compared between study and control groups. Results: Proportions of pbNK cells among peripheral blood monocytes (PBMC) ($14.2{\pm}5.2$ vs. $9.4{\pm}3.7%$, p=0.002, 95% confidence interval [CI], 1.8 to 7.8) was significantly higher in the patient group. The odds ratio of having RSA history was increased as 8.4 folds (59% of sensitivity, 80% of specificity, and 95% CI: 2.0 to 35.8) in patients who showed pbNK cells fraction above 12.1% which was determined as cut-off value by using ROC curve analysis. The cytolytic activities of pbNK cells which measured by three different ratio of effecter pbNK cells to target K562 cells and calculated by the percent of cytolytic K562 cells, were significantly higher in study group than that of control group (in 50:1 ratio, $48.3{\pm}19.0$ vs. $31.3{\pm}11.9%$, p=0.002; in 25:1 ratio, $37.0{\pm}18.1$ vs. $20.2{\pm}9.2%$, p<0.001; in 12.5:1 ratio, $23.5{\pm}12.7$ vs. $12.4{\pm}7.3%$, p=0.001). With the cut-off values of cytolytic activity of pbNK cells as 43.1% (50:1), 26.9% (25:1), and 17.4% (12.5:1) each, the risk of having RSA history was increased by 10.0, 11.4, and 15.0 folds in patients who had increased in each effector of pbNK to target of K562 cells ratio. Conclusion: The analysis of pbNK cells fraction and their cytolytic activity can be valuable diagnostic markers for RSA. We are going to planning the large scaled studies which include the data of obstetric outcomes in subsequent pregnancies to clarify our results of this study.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5695-5699
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• 2012

We investigated the relationships between demographics, lifestyle characteristics, and serum total prostate specific antigen (PSA) concentration and examined the population-based distribution of total PSA by age among 2,246 Korean men with a median age of 45 years. We obtained data about demographic and lifestyle characteristics based on self-reporting using a quetionnaire. We also performed physical examinations, anthropometric measurements, and biochemical measurements. The PSA concentration increased with age and there was a significant difference in total PSA concentration between the age groups of 21-60 years and >60 years. Age >60 years, height ${\geq}1.8$ m, a low frequency of alcohol consumption, and taking nutritional supplements showed a significantly increased odds ratio for increased PSA when 3.0 ng/mL was chosen as the PSA cut-off level. Smoking status, BMI, percent body fat, diabetes mellitus, fatty liver, herbal medicine use, vitamin use, and diet were not significantly associated with total PSA regardless of the cut-off level. When interpreting a single PSA test, height, alcohol consumption, and nutritional supplement use should be considered, in addition to age.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.240-245
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• 1998

Fuzzy information retrieval which uses the concept of fuzzy relation is able to retrieve documents in the way based on not morphology but semantics, dissimilar to traditional information retrieval theories. Fuzzy information retrieval logically consists of three sets : the set of documents, the set of terms and the set of queries. It maintains a fuzzy relational matrix which describes the relationship between documents and terms and creates a thesaurus with fuzzy relational product. It also provides the user with documents which are relevant to his query. However, there are some problems on building a thesaurus with fuzzy relational product such that it has big time complexity and it uses fuzzy values to be processed with flating-point. Actually, fuzzy values have to be expressed and processed with floating-point. However, floating-point operations have complex logics and make the system be slow. If it is possible to exchange fuzzy values with binary values, we could expect sp eding up building the thesaurus. In addition, binary value expressions require just a bit of memory space, but floating -point expression needs couple of bytes. In this study, we suggest a new method of building a thesaurus, which accelerates the operation of the system by pre-applying an ${\alpha}$-cut. The experiments show the improvement of performance and reliability of the system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.6
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• pp.64-71
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• 2000

An optical switch composed of identical, equally-spaced $Ti:LiNbO_3$ three-waveguides was designed and fabricated. Patterned Ti was diffused into z-cut $LiNbO_3$ substrates. $SiO_2$ buffer layer was evaporated to reduce the propagation loss of TM mode, and Al electrodes of CPW structure were built on the layer for switching of the guided beam. The optical switching phenomenon was confirmed when a beam of ${\lambda}=1.3{\mu}m$ was launched into the center waveguide and an electric field was applied to detune the three waveguides symmetrically.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.409-414
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• 2009

The SK Chemical R&D center is an eco-friendly building designed as top score in the GBCC(GREEN BUILDING CERTIFICATE CRITERIA). This building has applied various eco-friendly technologies such as energy /water resource cutdown, improvement of indoor quality and improvement of user convenience, etc through eco-friendly concept from the design phase. In this thesis, an economic efficiency evaluation has been performed on building energy cwater resource cutdown technologies among them and the results are as follows. The building energy has cut down about 40% compared to ordinary buildings and the investment recovery period was shown as about 5 years. The water resource has cut down about 63% compared to ordinary buildings and the investment recovery period was shown as about 10 years.

• Explosives and Blasting
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• v.26 no.2
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• pp.99-107
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• 2008

This study, to reduce a ground vibration damage of the structures in an area adjacent to housing structures located closely above the tunnel section, is the ground vibration reduction instance of a tunnel blasting selectively applied the ground vibration-controlled blasting method (delay time applied blasting method, large center hole cut method, Line Drilling method, etc) with an originally planned blasting method connected, but with it's workability and economic efficiency is satisfactory, so, the results says the ground vibration-controlled blasting method on a similar condition is very effective, even if the applicability is depend on the blasting method and ground condition of the work area.