• Geomechanics and Engineering
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• v.10 no.6
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• pp.737-755
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• 2016

The load transfer depth of a ground anchor is the minimum length required to transfer the initial prestressing to the grout column through the bonded part. A thorough understanding of the mechanism of load transfer as well as accurate prediction of the load transfer depth are essential for designing an anchorage that has an adequate factor of safety and satisfies implicit economic criteria. In the current research, experimental and numerical studies were conducted to investigate the load transfer mechanism of ground anchors based on a series of laboratory and field load tests. Optical FBG sensors embedded in the central king cable of a seven-wire strand were successfully employed to monitor the changes in tensile force and its distribution along the tendons. Moreover, results from laboratory and in-situ pullout tests were compared with those from equivalent case studies simulated using the finite difference method in the FLAC 3D program. All the results obtained from the two proposed methods were remarkably consistent with respect to the load increments. They were similar not only in trend but also in magnitude and showed more consistency at higher pullout loading stages, especially the final loading stage. Furthermore, the estimated load transfer depth demonstrated a pronounced dependency on the surrounding ground condition, being shorter in hard ground conditions and longer in weaker ones. Finally, considering the safety factor and cost-effective design, the required bonded length of a ground anchor was formulated in terms of the load transfer depth.

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.364-369
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• 2011

For the safety management of tunnel, effective measurements should be continuously carried out. Most of sensors currently being applied for tunnels measure only the local status, thus many of them are needed to monitor an entire tunnel. For the railway tunnel where trains of same conditions are regularly operated, dynamic responses of tunnel structure to train operations can be a good index to estimate the deformation of tunnel structure in wide area. Meanwhile, the electromagnetic interference caused by overhead centenary in railway tunnel obstructs the use of electric-based sensors. In this study a brand new accelerometer using FBG optical fiber sensors is developed to solve these problems. Sensitivity and capacity of the accelerometer are enhanced with effective structural design of its components and verified with laboratory tests. A case history where the developed accelerometers were applied to a safety monitoring system of a high-speed train tunnel is presented. The performances of the developed accelerometers are validated from the measured acceleration data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.269-274
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• 2011

The purpose of hull stress monitoring system(HSMS) is to lead hull structure to be safer at lower cost. We proposed a hull stress monitoring system for leisure boats using fiber-optic bragg grating(FBG) strain sensor. Fiber optic sensors are well suited for structure monitoring system, due to their ability to withstand harsh environments, immunity to electromagnetic interference, and reduce cabling installation cost when employing wavelength multiplexing. This paper presents an overview of current research and design of hull stress monitoring system for leisure boats.

• Archives of Plastic Surgery
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• v.48 no.4
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• pp.366-372
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• 2021

Background The result of illicit polymer injection is chronic inflammation with foreign-body granuloma (FBG) formation. Treatment can be divided into medical and surgical. Some patients develop severe complications with need surgical treatment. This study aims to describe patients who underwent surgical removal of the FBGs and autoimmune/inflammatory syndrome induced by adjuvants (ASIA); additionally, we evaluated the quality of life after surgery. Methods In this retrospective single-center study, the authors examined data of patients who underwent surgical removal of FBG caused by illicit polymer injection for cosmetic purposes and confirmed ASIA from 2015 to 2020 by three different surgical approaches. Descriptive summary statistics were reported on patient demographics, presenting symptoms and clinical examination features, treatment strategies, histopathology reports and quality of life. Results The cohort included 11 female patients with FBGs and ASIA. The most affected anatomical zones were the combination of gluteal region, thighs and legs (40%); and thighs with legs (20%). Main presentation was: skin hyperpigmentation (90.9%), skin induration (63.6%), chronic fatigue (63.6%), and ulcers (36.4%). Surgical modalities consisted of: ultrasonic-assisted liposuction in four patients (36.4%); open en bloc excision and primary closure in four patients (36.4%); and open en bloc excision and microsurgical reconstruction in three patients (27.2%). The postoperative quality of life visual analog scale score was 83.9. Conclusions ASIA treatment represents a challenge for the plastic surgeon. Adequate surgical treatment emphasizing, when possible, the total or near-total resection of the FBG must be performed to improve ASIA evolution.

• Nutrition Research and Practice
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• v.17 no.4
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• pp.789-802
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• 2023

BACKGROUND/OBJECTIVES: Habitual coffee consumption was inversely associated with type 2 diabetes (T2D) and hyperglycemia in observational studies, but the causality of the association remains uncertain. This study tested a causal association of genetically predicted coffee consumption with T2D using the Mendelian randomization (MR) method. SUBJECTS/METHODS: We used five single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs) associated with habitual coffee consumption in a previous genome-wide association study among Koreans. We analyzed the associations between IVs and T2D, fasting blood glucose (FBG), 2h-postprandial glucose (2h-PG), and glycated haemoglobin (HbA1C) levels. The MR results were further evaluated by standard sensitivity tests for possible pleiotropism. RESULTS: MR analysis revealed that increased genetically predicted coffee consumption was associated with a reduced prevalence of T2D; ORs per one-unit increment of log-transformed cup per day of coffee consumption ranged from 0.75 (0.62-0.90) for the weighted mode-based method to 0.79 (0.62-0.99) for Wald ratio estimator. We also used the inverse-variance-weighted method, weighted median-based method, MR-Egger method, and MR-PRESSO method. Similarly, genetically predicted coffee consumption was inversely associated with FBG and 2h-PG levels but not with HbA1c. Sensitivity measures gave similar results without evidence of pleiotropy. CONCLUSIONS: A genetic predisposition to habitual coffee consumption was inversely associated with T2D prevalence and lower levels of FBG and 2h-PG profiles. Our study warrants further exploration.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.83-87
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• 2022

Recently, as the thickness of the semiconductor package becomes thinner, warpage has become a major issue. Since the warpage is caused by differences in material properties between package components, it is essential to precisely evaluate the material properties of the EMC(Epoxy molding compound), one of the main components, to predict the warpage accurately. Especially, the cure shrinkage of the EMC is generated during the curing process, and among them, the effective cure shrinkage that occurs after the gelation point is a key factor in warpage. In this study, the gelation point of the EMC was defined from the dissipation factor measured using the dielectric sensor during the curing process similar with actual semiconductor package. In addition, DSC (Differential scanning calorimetry) test and rheometer test were conducted to analyze the dielectrometry measurement. As a result, the dielectrometry was verified to be an effective method for monitoring the curing status of the EMC. Simultaneously, the strain transition of the EMC during the curing process was measured using the FBG (Fiber Bragg grating) sensor. From these results, the effective cure shrinkage of the EMC during the curing process was measured.

• Clinical Nutrition Research
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• v.13 no.3
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• pp.201-213
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• 2024

This systematic review and meta-analysis of randomized controlled trials (RCTs) aimed to test our hypothesis that herbal tea may improve anthropometric parameters, metabolic factors, and hormone levels in women with polycystic ovarian syndrome (PCOS). A literature search was conducted on Information Sciences Institute, Medline (PubMed), Scopus, Embase, and Google Scholar, up to March 2023 without applying language or date restrictions. RCTs that assigned herbal tea vs. placebo on PCOS women and evaluated changes in anthropometric measurements, metabolic indices, or hormonal profiles were included. Six RCTs with 235 PCOS women (119 in the intervention and 116 in the control group) were included. Meta-analysis showed that herbal tea consumption led to significant decreases in weight (weighted mean difference [WMD], -2.02 kg; 95% confidence interval [CI], -3.25, -0.80), body mass index (BMI) (WMD, -0.88 kg/m²; 95% CI, -1.47, -0.28) and fasting blood glucose (FBG) (WMD, -6.47 mg/dL; 95% CI, -8.49, -4.45), compared to the control group. Herbal tea supplementation has also significantly increased follicle-stimulating hormone (FSH) concentration (WMD, 0.56 IU/L; 95% CI, 0.17, 0.95). Meanwhile, the effect of herbal tea on the waist/hip ratio, hip circumference, waist circumference, body fat, fasting insulin, FBG/insulin ratio, luteinizing hormone, total testosterone, and dehydroepiandrosterone sulfate was not significant. Herbal tea might be a potential supplemental therapy to manage weight, BMI, FBG, and FSH in PCOS women. Further large randomized clinical trials are recommended to affirm these findings.

• Archives of Plastic Surgery
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• v.37 no.3
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• pp.233-238
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• 2010

Purpose: As the use of soft tissue fillers becomes more popular, complications such as foreign body granuloma (FBG) are increasing. We report 120 cases of facial FBG and review the available literatures. Methods: 120 patients of facial FBG in our clinic from Mar. 2003 to Feb. 2008 were complied and analyzed. A retrospective chart review was done and patient satisfaction was evaluated with a questionnaire using 5 score scale. Patients with severe inflammation sign or bizarre deformity underwent surgical excision and those with minimal symptoms or a history of hyaluronic acid injection received injection therapy using hyaluronidase. Results: 100 females and 20 males were observed. The average age was 43.7 years (from 16 to 74). 84 patients received surgical therapy and 36, injection therapy. Deformity of facial contour, foreign body sensation and inflammation sign were the three main chief complaints. 84 patients did not know what the injection materials were. The known materials are as follows: collagen, hyaluronic acid, silicone oil, paraffin. 92 cases were performed by unlicensed practitioners, 29 by physicians. Anatomical site most frequently affected by the foreign body granuloma was the cheek (25.8%), followed by forehead (19.2%), lips (15.8%), nose (9.2%), mentum (8.3%), eyelid and eyebrow (4.3%) and temple (0.8%). In 21 patients (17.5%), FBGs were found on multiple sites. Patients with inflammation sign got the highest satisfaction ($3.19{\pm}0.73$) (p=0.001) among 3 chief complaints. And patient satisfaction was statistically higher in surgical therapy group ($3.43{\pm}0.72$) than in injection therapy group ($2.97{\pm}0.88$) (p=0.003). Conclusion: We suggest that it may be beneficial to tailor the type of treatment for FBG relying on wound state and patient's chief complaints. In surgical therapy, resolute approach is necessary to correct facial deformity definitely and to minimize inflammation. Injection therapy could be another option for those with minimal symptoms or a history of hyaluronic acid injection. To prevent foreign body granuloma, not only plastic surgeons but also other physicians should inject soft tissue fillers with great caution and we should warn the public of disastrous consequences associated with illegal medical practice.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.33-40
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• 2020

Various studies have been conducted on the structural health monitoring using optical fiber. Optical fibers can be used to measure multiple and distributed strain. Among the optical fiber sensors, FBG sensor has advantages of dynamic response measurement and high precision, but the number of measurement points is limited. Distributed fiber sensors, represented by distributed Brillouin sensors, usually have more than 1000 measurement points, but the low sampling rate makes dynamic measurements impossible. In this study, a hybrid nerve sensor system using only the advantages of the FBG sensor and the distributed Brillouin sensor has been proposed. Laboratory experiments were performed to verify the proposed system, and the accuracy and reproducibility were verified by comparing with commercial sensors. Applying the proposed system, dynamic response ambient measurements are used to evaluate the global state of the structure. When an abnormal condition is detected, the local condition of the structure is evaluated by static response measurement using the distributed measurement system. The proposed system can be used for efficient structural health monitoring.

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.241-246
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• 2018

In this paper, a low-cost optical temperature sensor is implemented, using a fiber Bragg grating (FBG) as the temperature probe and a low-cost VCSEL with temperature-dependent output wavelength as the light source. To analyze the wavelength of the reflected light from the FBG, an interrogation was applied using a method of referring to the internal temperature according to the output wavelength of the VCSEL. When the temperature of the VCSEL was adjusted from 14 to $52.2^{\circ}C$, the output wavelength varied from 1519.90 to 1524.25 nm. The degree of wavelength tuning according to temperature was $0.114nm/^{\circ}C$. The variable wavelength repeatability error according to temperature was ${\pm}0.003nm$, and the temperature measurement error was ${\pm}0.18^{\circ}C$. As a result of measuring the temperatures from 22.3 to $194.2^{\circ}C$, the value of the internal temperature change of the light source according to the applied temperature ${\Delta}T$ was $0.146^{\circ}C/{\Delta}T$, the change in reflected wavelength of the temperature probe according to applied temperature ${\Delta}T$ was measured at $16.64pm/^{\circ}C$. and the temperature measurement error of the sensor was ${\pm}1^{\circ}C$.