• Korean Journal of Optics and Photonics
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• v.26 no.2
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• pp.73-82
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• 2015

This work demonstrates the indoor SI-traceable calibration of a transmissometer with a 75-m baseline for the measurement of visibility in MOR (Meteorological Optical Range). The calibration is performed using a set of neutral density (ND) filters (OD 0.1-2.5) and a set of high-transmission quartz glass plates (a bare quartz glass plate and antireflective-coated quartz glass plates), the collection consisting of 20 artifacts in total. The luminous transmittance values of the reference artifacts had been calibrated traceable to the KRISS spectral transmittance scale, which ranges from 0.2 % to 99.5 %. The transmissometer to be calibrated typically consists of a loosely collimated light source based on a white LED (CCT ~5000 K) and a luminous intensity detector with a CIE 1924 V(${\lambda}$) spectral response. As a result of calibration, we obtained the MOR error and its uncertainty for the transmissometer in 20 m - 40 km of MOR. Based on the results, we investigated the applicability of the calibration method and the conformity of the transmissometer to the ICAO's (International Civil Aviation Organization) accuracy requirement for meteorological visibility measurement. We expect that this work will establish the standard procedure for the SI-traceable calibration of a transmissometer.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.5
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• pp.43-51
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• 2010

Attenuation coefficients of medical ultrasound not only reflect the pathological information of tissues scanned but also provide the quantitative information to compensate the decay of backscattered signals for other medical ultrasound parameters. Based on the frequency-selective attenuation property of human tissues, attenuation estimation methods in spectral domain have difficulties for real-time implementation due to the complexicity while estimation methods in time domain do not achieve the compensation for the diffraction effect effectively. In this paper, we propose the modified VSA method, which compensates the diffraction with reference phantom in time domain, using adaptive bandpass filters with decreasing center frequencies along depths. The adaptive bandpass filtering technique minimizes the distortion of relative echogenicity of wideband transmit pulses and maximizes the signal-to-noise ratio due to the random scattering, especially at deeper depths. Since the filtering center frequencies change according to the accumulated attenuation, the proposed algorithm improves estimation accuracy and precision comparing to the fixed filtering method. Computer simulation and experimental results using tissue-mimicking phantoms demonstrate that the distortion of relative echogenicity is decreased at deeper depths, and the accuracy of attenuation estimation is improved by 5.1% and the standard deviation is decreased by 46.9% for the entire scan depth.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.1
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• pp.31-43
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• 2015

This study had been aimed to conduct the camera calibration on VLBI antenna in the Space Geodetic Observation Center of Sejong City with a low-cost digital camera, which embedded in a mobile phone to determine the three-dimension position coordinates of the VLBI antenna, based on stereo images. The initial values for the camera calibration have been obtained by utilizing the Direct Linear Transformation algorithm and the commercial digital photogrammetry system, PhotoModeler $Scanner^{(R)}$ ver. 6.0, respectively. The accuracy of camera calibration results was compared with that the camera calibration results, acquired by a bundle adjustment with nonlinear collinearity condition equation. Although two methods showed significant differences in the initial value, the final calibration demonstrated the consistent results whichever methods had been performed for obtaining the initial value. Furthermore, those three-dimensional coordinates of feature points of the VLBI antenna were respectively calculated using the camera calibration by the two methods to be compared with the reference coordinates obtained from a total station. In fact, both methods have resulted out a same standard deviation of $X=0.004{\pm}0.010m$, $Y=0.001{\pm}0.015m$, $Z=0.009{\pm}0.017m$, that of showing a high degree of accuracy in centimeters. From the result, we can conclude that a mobile phone camera opens up the way for a variety of image processing studies, such as 3D reconstruction from images captured.

• Journal of Nutrition and Health
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• v.56 no.4
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• pp.391-403
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• 2023

Purpose: This study evaluated the validity of a physical activity classification table (PACT) based on total energy expenditure (TEE) and physical activity level (PAL) measured using the doubly labeled water (DLW) method in Korean adults and the elderly. Methods: A total of 141 (male 70, female 71) adults and elderly were included. The reference standards TEE_DLW, PAL_DLW were measured over a 14-day period using DLW. A 24-hour physical activity diary was kept for three days (two days during the week and one day on the weekend). PAL_PACT was calculated by classifying the activity type and intensity using the PACT. PAL_PACT was multiplied by resting energy expenditure measured by indirect calorimetry to estimate TEE_PACT. Results: The mean age of the study participants was 50.5 ± 18.8 years, and the mean body mass index was 23.4 ± 3.3 kg/m². A comparison of TEE_DLW and TEE_PACT by sex and age showed no significant differences. The bias, the difference between TEE_DLW and TEE_PACT, was male 17.3 kcal/day and female -4.5 kcal/day. The percentage of accurate predictions (values within ± 10% of the TEE_DLW) of TEE_PACT was 58.6% in males and 54.9% in females, with the highest prediction values in the age group 40-64 years (70.9%) in males and over 65 years (73.9%) in females. The spearman correlation coefficient (r) between TEE_PACT and TEE_DLW was 0.769, indicating a significant positive correlation (p < 0.001). Conclusion: In this study, the use of a new PACT for calculating TEE and PAL was evaluated as valid. A web version of the software program and a smartphone application need to be developed using PACT to make it easier to apply for research purposes.

• Journal of Gastric Cancer
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• v.15 no.4
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• pp.238-245
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• 2015

Purpose: This study aimed to identify time-dependent prognostic factors and demonstrate the time-dependent effects of important prognostic factors in patients with advanced gastric cancer (AGC). Materials and Methods: We retrospectively evaluated 3,653 patients with AGC who underwent curative standard gastrectomy between 1991 and 2005 at the Korea Cancer Center Hospital. Multivariate survival analysis with Cox proportional hazards regression was used in the analysis. A non-proportionality test based on the Schoenfeld residuals (also known as partial residuals) was performed, and scaled Schoenfeld residuals were plotted over time for each covariate. Results: The multivariate analysis revealed that sex, depth of invasion, metastatic lymph node (LN) ratio, tumor size, and chemotherapy were time-dependent covariates violating the proportional hazards assumption. The prognostic effects (i.e., log of hazard ratio [LHR]) of the time-dependent covariates changed over time during follow-up, and the effects generally diminished with low slope (e.g., depth of invasion and tumor size), with gentle slope (e.g., metastatic LN ratio), or with steep slope (e.g., chemotherapy). Meanwhile, the LHR functions of some covariates (e.g., sex) crossed the zero reference line from positive (i.e., bad prognosis) to negative (i.e., good prognosis). Conclusions: The time-dependent effects of the prognostic factors of AGC are clearly demonstrated in this study. We can suggest that time-dependent effects are not an uncommon phenomenon among prognostic factors of AGC.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9101-9105
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• 2014

Background: The purpose of this study was to compare the accuracy and effectiveness of automated breast volume scanning (ABVS) and hand-held ultrasound (HHUS) in the detection of breast cancer in a large population group with a long-term follow-up, and to investigate whether different ultrasound systems may influence the estimation of cancer detection. Materials and Methods: Institutional review board approval was obtained for this retrospective study, and informed consent was waived. From September 2010 to August 2011, a total of 1,866 ABVS and 3,700 HHUS participants, who underwent these procedures at our institute, were included in this study. Cancers occurring during the study and subsequent follow-up were evaluated. The reference standard was a combination of histology and follow-up imaging (${\geq}12months$). The recall rate, cancer detection yield, diagnostic accuracy, sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were calculated with exact 95% confidence intervals. Results: The recall rate was 2.57 per 1,000 (48/1,866) for ABVS and 3.57 per 1,000 (132/3,700) for HHUS, with a significant difference (p=0.048). The cancer detection yield was 3.8 per 1,000 for ABVS and 2.7 per 1,000 for HHUS. The diagnostic accuracy was 97.7% for ABVS and 96.5% for HHUS with statistical significance (p=0.018). The specificity of ABVS and HHUS were 97.8%, 96.7%, respectively (p=0.022). Conclusions: ABVS shows a comparable diagnostic performance to HHUS. ABVS is an effective supplemental tool for mammography in breast cancer detection in a large population.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.10
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• pp.1319-1324
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• 2010

The objectives of this study were to compare the effectiveness of different indicators of mammary inflammation in buffalo and to evaluate the association of the indicators with buffalo milk yield, composition, and rennet coagulation properties. This study was carried out at four buffalo farms in central Italy using a total of 50 lactating buffalo. Milk from each buffalo was tested at the beginning, middle, and end of lactation. To evaluate the relationship between mastitis markers and milk components, three classes were defined for each of the following markers: total somatic cell count (TSCC), differential somatic cell count (DSCC), and bacteriological results The regression coefficient for the reference method and the alternative method of determining TSCC was 0.81, indicating that the method routinely used to analyze buffalo milk consistently underestimated actual TSCC. The milk samples positive for udder-specific bacteria also had higher TSCC values than the samples that were negative for bacteria ($872{\times}10^3$/ml vs. $191{\times}10^3$/ml). In samples that were positive for udder-specific bacteria, polymorphonuclear leukocytes (PMN) made up greater than 50% of the cells. Moreover, only 1% of the samples in the lowest TSCC class were positive for bacteria. The correlation between TSCC and PMN was stronger (0.70), and PMN values in buffalo milk increased significantly when the TSCC class changed from low (38%) to medium and high (56% and 64%). Milk yield was negatively related to TSCC. Significant changes in lactose (4.87%, 4.80% and 4.64%) and chloride content (0.650 mg/ml, 0.862 mg/ml and 0.882 mg/ml) were also observed with increasing TSCC values. Higher TSCC was associated with impaired rennet coagulation properties: the clotting time increased, while the curd firming time ($p{\leq}0.05$) and firmness decreased. We concluded that in buffalo as in dairy cows, TSCC is a valid indicator of udder inflammation; we also confirmed that a value of $ 200{\times}10^3 cells/ml should be used as the threshold value for early identification of an animal affected by subclinical mastitis. In addition to its association with significantly decreased milk yield, a TSCC value above this threshold value was associated with changes in milk composition and coagulating properties.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.348-354
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• 2015

Urethane waterproofing materials which currently being used most commonly in the Korean domestic market have high applicability and construct layers without forming any joints, but under the influence of low temperature and low humidity, as well as the thickness of the applied layer, the curing time of this material may become extended in construction sites. To resolve these issues, a proposed method of using water-hardening type of polyurethane waterproofing materials are being developed. However, there currently lacks any standards or evaluation methods on determining an optimal mixture ratio of water for the water-hardening polyurethane waterproofing materials. Therefore, workers and construction workers are relying on their hands-on-skills and experience to determine this ratio and are not able to obtain a consistent performance quality out of these materials. Therefore, for the establishment of a board applicability of the water-hardening polyurethane waterproofing methods in construction sites, this study objectively analyzes the changes in the performance of these materials depending on the changes of the water mixture ratio and attempts to procure the optimal ratio on the basis of forming a provisionary standard. The study prepares mixtures of varying ratio(no water added, 5, 10, 15, 20, 25, 30, 40 and 50) and conducts comparative analysis respective mixtures' performances and their changes in the physical properties in an objective manner and proposes a provisional optimal value that can serve as a data base that can be used as a reference for future studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.679-687
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• 2021

The purpose of the present study was to document the standardization and management process of interface terminology regarding the chief complaints, diagnoses, and procedures, including surgery in a four-hospital consortium. The process was proposed, discussed, modified, and finalized in 2016 by the Terminology Standardization Committee (TSC), consisting of personnel from four hospitals. A request regarding interface terminology was classified into one of four categories: 1) registration of a new term, 2) revision, 3) deleting an old term and registering a new term, and 4) deletion. A request was processed in the following order: 1) collecting testimonies from related departments and 2) voting by the TSC. At least five out of the seven possible members of the voting pool need to approve of it. Mapping to the reference terminology was performed by three independent medical information managers. All processes were performed online, and the voting and mapping results were collected automatically. This process made the decision-making process clear and fast. In addition, this made users receptive to the decision of the TSC. In the 16 months after the process was adopted, there were 126 new terms registered, 131 revisions, 40 deletions of an old term and the registration of a new term, and 1235 deletions.

• Journal of Korea Water Resources Association
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• v.54 no.5
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• pp.347-354
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• 2021

In the past few years, various damages have occurred in the vicinity of rivers due to flooding. In order to alleviate such flood damage, structural and non-structural measures are being established, and one of the important non-structural measures is to establish a flood warning system. In general, in order to establish a flood warning system, the water level of the flood alarm reference point is set, the critical flow corresponding thereto is calculated, and the warning precipitation amount corresponding to the critical flow is calculated through the Geomorphological Instantaneous Unit Hydrograph (GIUH) rainfall-runoff model. In particular, when calculating the critical flow, various studies have calculated the critical flow through the Manning formula. To compare the adequacy of this, in this study, the critical flow was calculated through the HEC-RAS model and compared with the value obtained from Manning's equation. As a result of the comparison, it was confirmed that the critical flow calculated by the Manning equation adopted excessive alarm precipitation values and lead a very high flow compared to the existing design precipitation. In contrast, the critical flow of HEC-RAS presented an appropriate alarm precipitation value and was found to be appropriate to the annual average alarm standard. From the results of this study, it seems more appropriate to calculate the critical flow through HEC-RAS, rather than through the existing Manning equation, in a situation where various river projects have been conducted resulting that most of the rivers have been surveyed.