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"Lee, Hyo Sang"
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Empirical Study on Structural Safety Diagnosis of Large-Scale Civil Infrastructure Using Laser Scanning and BIM
Existing structural safety diagnosis methods are time-consuming due to personnel-oriented measurement methods and have a limitation that it is difficult to obtain consistent research results. In order to overcome these limitations, this study proposes a structural safety diagnosis method using laser scanning and BIM. In spite of the various studies related to laser scanning and BIM, it is difficult to find a study that verifies the effect of shortening the service period and cost reduction in terms of project management. Therefore, in this study, case analysis of structural safety diagnosis of large-scale civil infrastructure was conducted. In the structural safety diagnosis, the laser scanning data and the BIM model were compared and analyzed to determine the degree of deformation of pipe rack (e.g., truss, column). Laser scanning data reflects the deformation state of large-scale civil infrastructure. On the other hand, the BIM model was constructed by reflecting the state before the transformation with reference to the laser scanning data. Finally, proposed method of structural safety diagnosis saved four months. In terms of manpower saving, 125 man-month was saved. The research findings can provide a quantitative basis for the introduction of laser scanning and BIM technology in the structural safety diagnosis of aging large-scale civil infrastructures. However, the limitations of this study have not been analyzed economically by considering the investment cost (e.g., hardware, software, training, etc.) of laser scanning and BIM technology and the cost saving effect of technology introduction.
Journal Article
The value of CT, MRI, and PET-CT in detecting retropharyngeal lymph node metastasis of head and neck squamous cell carcinoma
Background
The diagnostic accuracies of the imaging studies should be clearly acknowledged in managing head and neck cancer patients; however, the accuracies of preoperative imaging studies in detecting retropharyngeal lymph node (RPLN) metastasis are still not clarified. This study was to evaluate diagnostic accuracies of computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) in detecting RPLN metastasis of head and neck squamous cell carcinomas.
Methods
For 123 patients who had performed RPLN dissection during the surgery of their squamous cell carcinoma of the head and neck, preoperative CT, MRI, and/or PET-CT were reviewed for RPLN metastasis in a blinded fashion by one experienced radiologist. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of each imaging modality were assessed, by comparing with the histopathologic findings of the resected RPLNs that served as the standard of reference.
Results
RPLNs were pathologically positive for metastasis in 43 of the 123 patients (35%). Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy in detecting metastasis to RPLN were 65, 94, 85, 83, and 84% for CT; 74, 94, 87, 87 and 87% for MRI; 83, 93, 89, 89 and 89% for PET-CT, respectively. When all the three imaging modalities were considered together (
n
= 74), they offered sensitivity of 90%, specificity of 91%, positive predictive value of 87%, negative predictive value of 93%, and accuracy of 91%.
Conclusions
The preoperative imaging studies offered relatively high specificity rates, but rather low sensitivity rates. The three imaging modalities altogether increased diagnostic accuracies, which highlights the potential of the three studies when used altogether can minimize missed diagnoses of RPLN metastasis.
Journal Article
Restoration of testis function in hypogonadotropic hypogonadal mice harboring a misfolded GnRHR mutant by pharmacoperone drug therapy
Mutations in receptors, ion channels, and enzymes are frequently recognized by the cellular quality control system as misfolded and retained in the endoplasmic reticulum (ER) or otherwise misrouted. Retention results in loss of function at the normal site of biological activity and disease. Pharmacoperones are target-specific small molecules that diffuse into cells and serve as folding templates that enable mutant proteins to pass the criteria of the quality control system and route to their physiologic site of action. Pharmacoperones of the gonadotropin releasing hormone receptor (GnRHR) have efficacy in cell culture systems, and their cellular and biochemical mechanisms of action are known. Here, we show the efficacy of a pharmacoperone drug in a small animal model, a knock-in mouse, expressing a mutant GnRHR. This recessive mutation (GnRHR E ⁹⁰K) causes hypogonadotropic hypogonadism (failed puberty associated with low or apulsatile luteinizing hormone) in both humans and in the mouse model described. We find that pulsatile pharmacoperone therapy restores E ⁹⁰K from ER retention to the plasma membrane, concurrently with responsiveness to the endogenous natural ligand, gonadotropin releasing hormone, and an agonist that is specific for the mutant. Spermatogenesis, proteins associated with steroid transport and steroidogenesis, and androgen levels were restored in mutant male mice following pharmacoperone therapy. These results show the efficacy of pharmacoperone therapy in vivo by using physiological, molecular, genetic, endocrine and biochemical markers and optimization of pulsatile administration. We expect that this newly appreciated approach of protein rescue will benefit other disorders sharing pathologies based on misrouting of misfolded protein mutants.
Journal Article
Enhancement of Drought Tolerance in Cucumber Plants by Natural Carbon Materials
Stress induced by climate change is a widespread and global phenomenon. Unexpected drought stress has a substantial effect on the growth and productivity of valuable crops. The effects of carbon materials on living organisms in response to abiotic stresses remain poorly understood. In this study, we proposed a new method for enhancing drought tolerance in cucumber (Cucumis sativus L.) using carbon nanotubes and natural carbon materials called shungite, which can be easily mixed into any soil. We analyzed the phenotype and physiological changes in cucumber plants grown under conditions of drought stress. Shungite-treated cucumber plants were healthier, with dark green leaves, than control plants when watering was withheld for 21 days. Furthermore, compared with the control cucumber group, in the shungite-treated plants, the monodehydroascorbate content of the leaf, which is a representative marker of oxidative damage, was 66% lower. In addition, major scavenger units of reactive oxygen species and related drought stress marker genes were significantly upregulated. These results indicate that successive pretreatment of soil with low-cost natural carbon material improved the tolerance of cucumber plants to drought stress.
Journal Article
Digital Vision Based Concrete Compressive Strength Evaluating Model using Deep Convolutional Neural Network
Compressive strength of concrete is a significant factor to assess building structure health and safety. Therefore, various methods have been developed to evaluate the compressive strength of concrete structures. However, previous methods have several challenges in costly, time-consuming, and unsafety. To address these drawbacks, this paper proposed a digital vision based concrete compressive strength evaluating model using deep convolutional neural network (DCNN). The proposed model presented an alternative approach to evaluating the concrete strength and contributed to improving efficiency and accuracy. The model was developed with 4,000 digital images and 61,996 images extracted from video recordings collected from concrete samples. The experimental results indicated a root mean square error (RMSE) value of 3.56 (MPa), demonstrating a strong feasibility that the proposed model can be utilized to predict the concrete strength with digital images of their surfaces and advantages to overcome the previous limitations. This experiment contributed to provide the basis that could be extended to future research with image analysis technique and artificial neural network in the diagnosis of concrete building structures.
Journal Article
Correlation between private education costs and parental depression in South Korea
Background
In Korea, higher education has rapidly grown influenced by sociocultural tradition. Parents invest a significant portion of their household income in their children’s education. Private education has been considered to greatly affect students’ psychology and behavior. However, past research has largely neglected to study parents who pay these costs. Since household income and education level are important determinants of socioeconomic status (SES), education expenditures are likely to cause depressive symptoms. Therefore, the study aimed to investigate the correlation between private education costs and parental depression in South Korea.
Methods
Data were collected from the Korean Welfare Panel Study (KoWePS, 2015, 2018). The sample analyzed consisted of 397 and 337 fathers and 403 and 370 mothers in 2015 and 2018, respectively. The independent variable in this study was the proportion of private education cost. This proportion was calculated by dividing each household’s private education costs by its equivalized household disposable income (EHDI) and multiplying this number by 100. The main dependent variable was parental responses to the Center for Epidemiologic Studies Depression Scale-11 (CESD-11). Using a generalized linear model, we investigated the effects of the proportion of private education cost on parental depression.
Results
The results showed that fathers with higher proportions of private education cost exhibited higher CESD-11 scores compared to fathers with lower proportions cost (moderate: β = 0.419, S. E = 0.164,
p
= 0.0105; high: β = 0.476, S. E = 0.178,
p
= 0.0076), indicating that a higher ratio of private education cost may negatively affect depression in fathers. However, there was no discernable correlation between mothers’ CESD-11 scores and the proportion of private education cost (moderate: β = − 0.078, S. E = 0.250,
p
= 0.7555; high: β = 0.003, S. E = 0.215,
p
= 0.9882).
Conclusions
These results may be explained by the tendency for fathers to experience greater economic burdens than mothers in patriarchal Korean society.
Journal Article
Metformin discontinuation less than 72 h is suboptimal for F-18 FDG PET/CT interpretation of the bowel
Objective
Metformin-induced [F-18] fluorodeoxyglucose (FDG) bowel uptake can hinder positron emission tomography/computed tomography (PET/CT) evaluation of the bowel. This study aimed to investigate the segmental bowel uptake of FDG according to metformin discontinuation times up to 72 h.
Methods
We retrospectively divided 240 diabetic patients into four groups: metformin discontinuation <24 h (group A;
n
= 86), 24–48 h (group B;
n
= 40), 48–72 h (group C;
n
= 12), and no metformin (control group;
n
= 102). Segmental FDG bowel uptakes were measured visually (four-point scale) and semi-quantitatively (maximum standardized uptake value).
Results
Compared with the control group, FDG uptake increased significantly from the ileum to the rectosigmoid colon in group A, from the transverse to the rectosigmoid colon in group B, and from the descending colon to the rectosigmoid colon in group C in both visual and semi-quantitative analyses.
Conclusions
Metformin discontinuation for <72 h is likely suboptimal for PET/CT image interpretation, especially with respect to the distal segments of the colon.
Journal Article
Effect of Chlorides on Conductivity and Dielectric Constant in Hardened Cement Mortar: NDT for Durability Evaluation
Dielectric constant and conductivity, the so-called EM properties (electromagnetic), are widely adopted for NDT (Nondestructive Technique) in order to detect damage or evaluate performance of concrete without damage to existing RC (reinforced concrete). Among deteriorating agents, chloride ion is considered as one of the most critical threats due to rapid penetration and direct effect on steel corrosion. In the work, cement mortar samples with 3 w/c (water-to-cement) ratios and 4 levels of chloride addition are considered. Conductivity and dielectric constant are measured in the normal frequency range. They increase with strength of mortar and more chloride ions due to denser pore formation. Furthermore, the behaviors of measured EM property are investigated with carbonation velocity and strength, which shows an attempt of application to durability evaluation through EM measurement.
Journal Article