• Journal of the Korean Society for Nondestructive Testing
• /
• v.29 no.2
• /
• pp.153-161
• /
• 2009

After several PWSCCs were found in Bugey(France), Ringhals(Sweden), Tihange(Belgium), Oconee, Arkansas, Crystal Fever, Davis-Basse, VC Summer(U.S.A.), Thuruga(Japan), USNRC and PNNL started the research on PWSCC, that is, PINC project. The aim of this project is to fabricate and obtain representative NDE mock-ups with flaws to simulate tight PWSCC cracks, to identify and quantitatively assess NDE methods for accurately detecting, sizing and characterizing tight cracks such as PWSCC, to document the range of locations and crack morphologies associated with PWSCC and observed responses and to incorporate findings from other ongoing PWSCC research programs, as appropriate. By participating in PINC project, Korean morphology technique about PWSCC and NDE technique have improved and become similar lever with other advanced country. Therefore, the evaluation technique of integrity for nickel alloy component has been improved by cooperation with university, research institute and industries.

• Korean Journal of Cognitive Science
• /
• v.21 no.2
• /
• pp.309-338
• /
• 2010

In this paper, we studied the brain-computer interface (BCI). BCIs help severely disabled people to control external devices by analyzing their brain signals evoked from motor imageries. The findings in the field of neurophysiology revealed that the power of $\beta$(14-26 Hz) and $\mu$(8-12 Hz) rhythms decreases or increases in synchrony of the underlying neuronal populations in the sensorymotor cortex when people imagine the movement of their body parts. These are called Event-Related Desynchronization / Synchronization (ERD/ERS), respectively. We implemented a BCI-based mouse interface system which enabled subjects to control a computer mouse cursor into four different directions (e.g., up, down, left, and right) by analyzing brain signal patterns online. Tongue, foot, left-hand, and right-hand motor imageries were utilized to stimulate a human brain. We used a non-invasive EEG which records brain's spontaneous electrical activity over a short period of time by placing electrodes on the scalp. Because of the nature of the EEG signals, i.e., low amplitude and vulnerability to artifacts and noise, it is hard to analyze and classify brain signals measured by EEG directly. In order to overcome these obstacles, we applied statistical machine-learning techniques. We could achieve high performance in the classification of four motor imageries by employing Common Spatial Pattern (CSP) and Linear Discriminant Analysis (LDA) which transformed input EEG signals into a new coordinate system making the variances among different motor imagery signals maximized for easy classification. From the inspection of the topographies of the results, we could also confirm ERD/ERS appeared at different brain areas for different motor imageries showing the correspondence with the anatomical and neurophysiological knowledge.

• Journal of the Korea Concrete Institute
• /
• v.25 no.1
• /
• pp.53-61
• /
• 2013

A new deformation of reinforcing bar in coils was proposed to improve a machinability of straightening process, which has crescent-shaped transverse ribs with an inclination angle of 50 degrees, a crest width of $0.15d_b$, and a flank inclination of 55 degrees. The proposed deformation can increase contact area between a surface of re-bar and a groove of a roller during a straightening process and, therefore, it might reduce a damage of ribs, improve a final straightness, and enhance an efficiency of the straightening process. Splice tests were conducted to evaluate bond strengths of three types of re-bar in coils including the proposed re-bar, of which the inclination angles of transverse ribs were 50, 60, and 90 degrees, respectively. Test results show that the re-bars in coils have higher bond strengths than predicted strengths by equations of Orangun et al., ACI 408, and KCI by at least 10%. Correlation coefficients of bond strengths between a straight bar and re-bars in coils are 0.94 and more. Consequently, equations of the KCI code for determining development and splice lengths can be applied to the tested re-bars in coils.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.1
• /
• pp.47-53
• /
• 2003

This study evaluated the influence of chemomechanical caries removal agent $Carisolv^{TM}$(MediTeam, Sweden) for composite resin adhesion to sound human permanent and primary dentin. The buccal/labial surfaces of 80 permanent molars and 80 primary incisors were used. Four types of adhesives and one composite resin were used; AQ Bond(Sun Medical, Japan), Clearfil SE Bond(Kuraray, Japan), Single Bond(3M, USA), Scotchbond Multi-Purpose(3M, USA) and Z100(3M, USA). One drop of $Carisolv^{TM}$(MediTeam, Sweden) was pretreated on the dentin for 0 second(control) and 60 seconds. The specimens were thermocycled for 1,000 times in baths kept 5 degrees C and 55 degrees C with a 30 seconds dwell time. Shear bond strengths were tested and the data was statistically analyzed using one-way ANOVA with subsequent post hoc Scheffe test at p<0.05. $Carisolv^{TM}$ treatment significantly decreased the shear bond strength. Shear bond strength of permanent dentin was significantly higher than that of primary dentin. Clearfil SE Bond treatment groups showed the highest shear bond strength and AQ Bond treatment groups showed the lowest shear bond strength.

• Tuberculosis and Respiratory Diseases
• /
• v.48 no.5
• /
• pp.699-708
• /
• 2000

Background : A presumptive histopathologic diagnosis of tuberculosis is commonly based on the finding of acid-fast bacilli upon microscopic examination of a diagnostic specimens. Although this traditional histochemical staining method is satisfactory, it is time-consuming and not species-specific. For more specific assessment, in situ hybridization assay with oligonucleotide probes is introduced. Methods : The human surgical specimens were obtained from tuberculosis patients, and experimental specimens were made by injecting cultured M. tuberculosis organisms into fresh rat liver. Oligonucleotide probes complementary to ribosomal RNA portion were synthesized and labeled with multiple biotin molecules. For a rapid detection, all procedures were carried out using manual capillary action technology on the Microprobe staining system. Results : The in situ hybridization assay produced a positive reaction in experimental specimens (80-90% sensitivity) after pepsin-HCl pre-treatment for a good permeabilization of probes, but reliable result was not obtained from human surgical specimens. Conclusion : It is, therefore, suggested that biotin-labeled oligonucleotide probes have considerable potential for identification and in situ detection of M. tuberculosis but, there are some barriers to overcome for the diagnostic use of this method.

• Journal of Internet Computing and Services
• /
• v.21 no.2
• /
• pp.81-90
• /
• 2020

The purpose of this study is to study how to apply block-chain technology to prevent data forgery and alteration in the defense sector of AI(Artificial intelligence). AI is a technology for predicting big data by clustering or classifying it by applying various machine learning methodologies, and military powers including the U.S. have reached the completion stage of technology. If data-based AI's data forgery and modulation occurs, the processing process of the data, even if it is perfect, could be the biggest enemy risk factor, and the falsification and modification of the data can be too easy in the form of hacking. Unexpected attacks could occur if data used by weaponized AI is hacked and manipulated by North Korea. Therefore, a technology that prevents data from being falsified and altered is essential for the use of AI. It is expected that data forgery prevention will solve the problem by applying block-chain, a technology that does not damage data, unless more than half of the connected computers agree, even if a single computer is hacked by a distributed storage of encrypted data as a function of seawater.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_2
• /
• pp.1881-1890
• /
• 2021

Particulate matter (PM) affects the human, ecosystems, and weather. Motorized vehicles and combustion generate fine particulate matter (PM_2.5), which can contain toxic substances and, therefore, requires systematic management. Consequently, it is important to monitor and predict PM_2.5 concentrations, especially in large cities with dense populations and infrastructures. This study aimed to predict PM_2.5 concentrations in large cities using meteorological and chemical variables as well as satellite-based aerosol optical depth. For PM_2.5 concentrations prediction, a random forest (RF) model showing excellent performance in PM concentrations prediction among machine learning models was selected. Based on the performance indicators R², RMSE, MAE, and MAPE with training accuracies of 0.97, 3.09, 2.18, and 13.31 and testing accuracies of 0.82, 6.03, 4.36, and 25.79 for R², RMSE, MAE, and MAPE, respectively. The variables used in this study showed high correlation to PM_2.5 concentrations. Therefore, we conclude that these variables can be used in a random forest model to generate reliable PM_2.5 concentrations predictions, which can then be used to assess the vulnerability of schools to PM_2.5.

• Journal of the Korean Institute of Gas
• /
• v.24 no.6
• /
• pp.47-54
• /
• 2020

A brittle fracture is one of the source of structural damage and can bring a fatal accident. The inner shell of LNG storage tank should be designed and applied to construction by ensure that no brittle crack will occur under -162℃ condition. In point of view of fracture mechanics brittle fracture in the structure could be referred as crack initiation and crack arrest. It should be designed no crack initiation. However, in the unlikely event of a brittle fracture occurring, a back-up function of arresting the brittle crack should be included for the design. In this paper investigated the characteristics of 9% Ni steel thick plates of having a capability of arresting brittle cracks under the thickness of 33 mm, 37mm, 40 mm. First, charpy test has performed to evaluate the fundamental brittle impact fracture property of 9% Ni steel under the temperature of 24℃, -162℃ and -196℃. In addition, Duplex ESSO tests were also performed under -196℃ to evaluate the capability of crack arrest for 9% Ni steel. From the experiments results, it was confirmed that all the thickness of 9% Ni steel plates exhibits sufficient brittle crack arrest fracture toughness for the application of LNG storage tank as a inner shell.

• Biomedical Science Letters
• /
• v.2 no.2
• /
• pp.133-151
• /
• 1996

After cardiac surgery, it has been recognized that various complications were associated with injured humoral and cellular immunity by cardiopulmonary bypass(CPB). Especially, in postoperative pulmonary dysfunction, transpulmonary leukostasis followed complement activation and inflammatory responses are major pathogen. Some studies have showed that pretreated-corticosteroids before CPB protected postoperative pulmonary dysfunction. Corticosteroids may inhibit complement and leukocyte activation. On based previous studies, present investigator determined changes of leukocyte counts and transpulmonary leukostasis during cardiac surgery and postoperative periods. For the evaluation of postoperative pulmonary function and edema, $PaO_2$ and chest X-ray were compared between pre-CPB and post-CPB. Fever and other parameters were also observed postoperatively. The aim of this study was to define for the prophylactic effects of corticosteroid(Solu-Medrol: 30mg/kg) on all the researched parameters. This study was prospectively designed with randomized-blind fashion for 50 patients undergoing cardiac surgery. According to the purpose of study, all patients were divided into placebo and steroid group. : Placebo group was 25 patients received normal saline(not corticosteroid), and steroid group was 25patients received corticosteroid(Solu-Medrol: 30mg/kg) before initiation of CPB. The results of study were summarized as follows. 1. Total peripheral leukocyte counts decreased significantly at 5 minutes of CPB in all patients(P<0.01), and began to increase progressively at later periods of CPB with neutrophilia. The significant rise remained at postoperative 7th day(P<0.05). 2. During partial CPB, transpulmonary leukostasis occurred in placebo group(P<0.001), whereas it was prevented in steroid group. 3. In both groups, peripheral lymphocyte counts were stable during CPB, but began to reduce at time of intensive care unit(ICU) and the lymphocytopenia remained until postoperative 3rd day. The lymphocyte counts recovered on postoperative 7th day. 4. In both groups, peripheral counts of monocyte were relatively stable in the early peroid of CPB, and increased gradually in the later periods of CPB. This significant monocytosis remained throughout postoperlative periods(P<0.05). 5. The mean value of postoperative $paO)_2$ was lower than that of pre-CPB in placebo group(P=0.01) but didn't significant in steroid group(P=0.90). In the incidence of pulmonary edema signs and fever, placebo group was higher than steroid group(P=0.001, p=0.01, respectively). However mechanical respiratory supporting and care periods at intensive care unit were not significant difference between two groups(P>.0.05).With the above results, the investigator concluded that leukocyte activation and pulmonary sequestration were caused by cardiac surgery with CPB and demonstrated that high dose corticosteroid will provide prophylactic effect for pulmonary leukostasis and higher neutrophilia. These effects may ameliorate postoperative pulmonary dysfunction and contribute to postoperative less morbidity. However, further study should be performed because postoperative lymphocytopenia continued for 3 days in both groups, which may suspected damage or suppression of cell-mediated immunity with used corticosteroid.

• Journal of Chest Surgery
• /
• v.43 no.6
• /
• pp.596-601
• /
• 2010

Background: This study was designed to evaluate the efficacy of a mixture of hyaluronic acid and sodium carboxymethyl cellulose ($Guardix-sol^{(R)}$) on experimental pericardial adhesion. Material and Method: Thirty rats were divided into 2 groups of 15 rats each and pericardial mesothelial injury was induced during surgery by abrasion. In the control group, blood and normal saline were administered into pericardium; in the test group, blood and HA-CMC solution were administered. Pericardial adhesions were evaluated at 2 weeks (n=5), 4 weeks (n=5), and 6 weeks (n=5) after surgery. The severity of adhesions was graded by macroscopic examination, and the adhesion tissue thickness was analyzed microscopically with Masson trichrome stain and an image processing program. Result: The test group had significantly lower macroscopic adhesion scores ($2.9{\pm}0.6$ : $3.9{\pm}0.4$, p<0.000) compared with the control group. For microscopic adhesion tissue thickness, the test group had lower scores compared with the control group, but this difference was not statistically significant ($91.73{\pm}49.91$ : $117.67{\pm}46.4$, p=0.106). Conclusion: We conclude that an HA-CMC solution ($Guardix-sol^{(R)}$) reduces the formation of pericardial adhesions in this animal model.