• Structural Engineering and Mechanics
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• v.90 no.1
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• pp.83-96
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• 2024

This paper suggests an analytical approach to investigate the free vibration and stability of functionally graded (FG) beams with both perfect and imperfect characteristics using a quasi-3D higher-order shear deformation theory (HSDT) with stretching effect. The study specifically focuses on FG beams resting on variable elastic foundations. In contrast to other shear deformation theories, this particular theory employs only four unknown functions instead of five. Moreover, this theory satisfies the boundary conditions of zero tension on the beam surfaces and facilitates hyperbolic distributions of transverse shear stresses without the necessity of shear correction factors. The elastic medium in consideration assumes the presence of two parameters, specifically Winkler-Pasternak foundations. The Winkler parameter exhibits variable variations in the longitudinal direction, including linear, parabolic, sinusoidal, cosine, exponential, and uniform, while the Pasternak parameter remains constant. The effective material characteristics of the functionally graded (FG) beam are assumed to follow a straightforward power-law distribution along the thickness direction. Additionally, the investigation of porosity includes the consideration of four different types of porosity distribution patterns, allowing for a comprehensive examination of its influence on the behavior of the beam. Using the virtual work principle, equations of motion are derived and solved analytically using Navier's method for simply supported FG beams. The accuracy is verified through comparisons with literature results. Parametric studies explore the impact of different parameters on free vibration and buckling behavior, demonstrating the theory's correctness and simplicity.

• Korean Journal of Radiology
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• v.24 no.11
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• pp.1061-1080
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• 2023

Artificial intelligence (AI) in radiology is a rapidly developing field with several prospective clinical studies demonstrating its benefits in clinical practice. In 2022, the Korean Society of Radiology held a forum to discuss the challenges and drawbacks in AI development and implementation. Various barriers hinder the successful application and widespread adoption of AI in radiology, such as limited annotated data, data privacy and security, data heterogeneity, imbalanced data, model interpretability, overfitting, and integration with clinical workflows. In this review, some of the various possible solutions to these challenges are presented and discussed; these include training with longitudinal and multimodal datasets, dense training with multitask learning and multimodal learning, self-supervised contrastive learning, various image modifications and syntheses using generative models, explainable AI, causal learning, federated learning with large data models, and digital twins.

• Parasites, Hosts and Diseases
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• v.62 no.1
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• pp.85-97
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• 2024

This study aimed to describe the morphological and molecular characteristics of Paralecithodendrium longiforme (Digenea: Lecithodendriidae) adults and cercariae isolated in Thailand. Adult flukes were isolated from the Chinese pipistrelle bat (Hypsugo sp.), and cercariae were detected in the viviparid snail (Filopaludina martensi martensi) from Chiang Mai province. The morphological characteristics were observed and described using conventional methods, and the molecular characteristics with internal transcribed spacer 2 (ITS2) and 28S rDNA gene sequences. The adult flukes were fusiform, 0.84-0.98 mm in length, and 0.37-0.49 mm in width, and were distinguishable from other species by the presence of longitudinal uterine coils. The cercariae were nonvirgulate xiphidiocercariae, with the oral sucker bigger than the acetabulum, the tail without fin fold, a body size of 117.5-138.3×48.3-52.2 ㎛, and a tail size of 100.7-103.7×15.0-18.9 ㎛. Molecular studies revealed that the adults and cercariae shared 99.3% (ITS2) and 99.6% (28S rDNA) homology with each other. They were phylogenetically close to P. longiforme with an identity of 94.5% for ITS2 and 98.7% for 28S rDNA. This study provides new information on the natural definitive host and first intermediate host of P. longiforme in Thailand. The discovery of its cercarial stage in Filopaludina snails highlights the importance of monitoring the associated second intermediate host and prevention and control of this potentially zoonotic trematode.

• Korean Journal of Psychosomatic Medicine
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• v.25 no.2
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• pp.153-165
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• 2017

Objectives : Recent neuroimaging studies focus on dysfunctions in connectivity between cognitive circuits and emotional circuits: anterior cingulate cortex that connects dorsolateral orbitofrontal cortex and prefrontal cortex to limbic system. Previous studies on pediatric depression using DTI have reported decreased neural connectivity in several brain regions, including the amygdala, anterior cingulate cortex, superior longitudinal fasciculus. We compared the neural connectivity of psychotropic drug naïve adolescent patients with a first onset of major depressive episode with healthy controls using DTI. Methods : Adolescent psychotropic drug naïve patients(n=26, 10 men, 16 women; age range, 13-18 years) who visited the Korea University Guro Hospital and were diagnosed with first onset major depressive disorder were registered. Healthy controls(n=27, 5 males, 22 females; age range, 12-17 years) were recruited. Psychiatric interviews, complete psychometrics including IQ and HAM-D, MRI including diffusion weighted image acquisition were conducted prior to antidepressant administration to the patients. Fractional anisotropy(FA), radial, mean, and axial diffusivity were estimated using DTI. FMRIB Software Library-Tract Based Spatial Statistics was used for statistical analysis. Results : We did not observe any significant difference in whole brain analysis. However, ROI analysis on right superior longitudinal fasciculus resulted in 3 clusters with significant decrease of FA in patients group. Conclusions : The patients with adolescent major depressive disorder showed statistically significant FA decrease in the DTI-based structure compared with healthy control. Therefore we suppose DTI can be used as a bio-marker in psychotropic drug-naïve adolescent patients with first onset major depressive disorder.

• Korean Journal of Environment and Ecology
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• v.30 no.6
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• pp.1067-1072
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• 2016

In this study, we determined the ecological characteristics of Strix aluco, which is designated as an endangered category II species. Towards this, we identified the actual home range of Strix aluco that breed in Korea, and collected the data necessary for protecting, preserving and managing owl populations. This study was conducted from April 14 to May 20 of 2016 during the breeding season of Strix aluco as part of the 4th National Ecosystem Survey and in accordance with the Natural Environment Conservation Act. We captured and subsequently released a female owl with a total length of 423.5mm and a weight of 550g in Kyungbuk area, succeeded in tracking it for the first time in Korea and secured 6 points of direct observation and satellite tracking observation. The distance from the nest to the farthest point was 93m. As a result of the analysis of habitat points within a100m-radius during breeding period, it was established that their habitat consists of 34.2% of non-irrigated land, 30.6% of mixed forest land, 10.5% of orchard, and 9.4% of natural grassland. These findings are consistent with the previous estimate of home range studies. Further research based on follow-up studies on males or other individuals is required to develop a stronger basis for protection and conservation of endangered wildlife class II owls.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.2
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• pp.48-60
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• 2000

This study is aimed to clarify the distribution chracteristics of marine terraces and extract the specific surface at Gampo-eup, Gyeongju city on the map of 1:5,000 using GIS. The effects and problems occurred on the process of using GIS were investigated for the research of marine terrace. The longitudinal profile analysis was carried out along the 12 sections on the geomorphic surfaces of the study area, and actually High higher surface(HH-surface) was found over 100m a.s.l., which has not been reported till now. And the occupancy rate could be calculated by substitution on the height between 4m and 87m a.s.l. for each mean slope degree $1-5^{\circ}$ obtained from the actual measuring along four sections. Consequently the lower-I surface was highly reliable to use as the key bed for studying marine terraces. The accurate and detail analysis about the marine terraces is able to be accomplished on the basis of meaningful actual measuring, though its general possible distribution area can be extracted from GIS with the less effort. Namely the quantified results obtained from GIS could offer the basis for the objective analysis of the geomorphic surfaces. And we can look over the landscape and investigate the surfaces with reliefs effectively in relation to the real geomorphology on the study area, where in situ approach is difficult. But the digital map with a large scale should be offered first of all in order to raise the accuracy of the analysis.

• Journal of Gastric Cancer
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• v.12 no.3
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• pp.149-155
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• 2012

Purpose: Although serosal invasion is a critical predisposing factor for peritoneal dissemination in advanced gastric cancer, the accuracy of preoperative assessment using routine imaging studies is unsatisfactory. This study was conducted to identify high-risk group for serosal invasion using preoperative factors in patients with advanced gastric cancer. Materials and Methods: We retrospectively analyzed clinicopathological features of 3,529 advanced gastric cancer patients with Borrmann type I/II/III who underwent gastrectomy at Korea Cancer Center Hospital between 1991 and 2005. We stratified patients into low-(${\leq}40%$), intermediate-(40~70%), and high-risk (>70%) groups, according to the probability of serosal invasion. Results: Borrmann type, size, longitudinal and circumferential location, and histology of tumors were independent risk factors for serosal invasion. Most tumors of whole stomach location or encircling type had serosal invasion, so they belonged to high-risk group. Patients were subdivided into 12 subgroups in combination of Borrmann type, size, and histology. A subgroup with Borrmann type II, large size (${\geq}7$ cm), and undifferentiated histology and 2 subgroups with Borrmann type III, large size, and regardless of histology belonged to high-risk group and corresponded to 25% of eligible patients. Conclusions: This study have documented high-risk group for serosal invasion using preoperative predictors. And risk stratification for serosal invasion through the combination with imaging studies may collaboratively improve the accuracy of preoperative assessment, reduce the number of eligible patients for further staging laparoscopy, and optimize therapeutic strategy for each individual patient prior to surgery.

• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.891-904
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• 1997

Today's orthodontic treatment goals lie in functional esthetics, and the importance of the latter is increasing gradually in trend. Considering such, study on growth and development of soft as well as hard tissues becomes inevitable. Early studies emphasize mainly on skeletal analysis using cephalometric data. However, more recent studies report that maxillofacial soft tissue, which plays a critical role in determining facial esthetics, is influenced by underlying hard tissue, and yet close relationship between them was not noticed. Cephalometric x-rays were taken of 137 Korean boys and 106 girls with no systemic disease, fair developmental status and normal occlusion for two consecutive years; afterwards, soft tissue analysis, which was divided into four parts, facial form lip position & posture, nose, and thickness, was done to correlate them with general growth.

• The Korean Journal of Pharmacology
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• v.15 no.1_2 s.25
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• pp.29-37
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• 1979

The tension-length relationships and reactivity of vascular smooth muscle in longitudinal strips from portal vein ana in helical strips from thoracic aorta and pulmonary artery of normotensive control and cadmium-hypertensive rabbits were studied in vitro. 1. The mean arterial pressures of non-poisoned control rabbits was $87.0{\pm}4.7 mmHg$. However, Cd-poisoned group revealed the significant increase in pressure by $109.04{\pm}2.8 mmHg$ (p<0.005). 2. By tension-length studies, strips from portal vein of Cd-poisoned group stretched a greater percent increase in length in response to an applied resting force from 0.25 to 5 g than did those from non-poisoned group. On the contrary, strips from thoracic aorta of Cd-poisoned group showed less compliant than those from control, i.e. the former underwent a less percent increase in length than the latter. Passive tension-length relations of pulmonary artery was unaffected by Cd-hypertension. 3. The force of contraction(active tension) was significantly lowered in strips from aorta of Cd-hypertensive group throughout the range of $0.5{\sim}2g$ passive tension. However, there was no significant difference in the development of active tension of portal vein or pulmonary artery of both groups. 4. The $K^+$-contraction in the portal vein, aorta and pulmonary artery of Cd-poisoned group made no difference in the active force from those of control group. 5. The force of contraction in the strips from aorta of Cd-poisoned group was significanty decreased compared to that of control. The results suggested that the alterations in vascular reactivity to contracting substances and in distensibility to passive tension were induced in the Cd-hypertensive rabbits.

• Journal of the East Asian Society of Dietary Life
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• v.5 no.1
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• pp.41-51
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• 1995

Bone mass accretion during puberty appears to be critical in the development of peak bone mass. Although bone density of females in Korea has been studied, only a few studies have related bone mass with anthropometric patterns or puberty in the pubescent girls. This study was conducted as part of a study of major determinants of bone development during puberty. Subjects were aged 14∼16 yr(mean 14.97), and had no history of disorders or dedication use likely to influence bone or calcium metabolism. Bone mineral density and content were measured by dual energy X-ray absorptiometry using a Lunar DPX+Scanner (Lunar Madison, WI). Also, total body fat, and total lean body mass were assessed using a Lunar DPX dual-energy X-ray absorptiometer, Pubertal status was assessed according to the Marshall and Tanner guidelines. Serum levels of osteocalcin was measured by RIA using a commercial kit assay. Skinfold measurements were taken with a skinfold caliper(Lange Caliper, USA). Data were analyzed using the regression and GLM procedure of the statistical package SAS. The results indicated that the observed means for lumbar spine BMD and femoral BMD correspond to approximately 91% and 96% of the means for young adult females, respec tively. All subjects were menarchal, with the majority being in the middle to end stages of pubertal development. Total body BMD was positively related to fat mass(P<0.001), lean body mass and time since menarche, and negatively related to urine pyridinoline, serum alkaline phosphatase and osteocalcin. The data indicate that girls who reported lower age for menarche had significantly higher bone densities than girls who reported higher age for menarche. Attaining peak skeletal bone mass during puberty may reduce the incidence of osteoporosis in later life. this finding suggests that early menarche may augment peak bone mass, influencing the extent of bone loss later in adulthood. The results suggest that good nutrition in childhood appears to be needed not for growth and development, but possibly also to assure an optimal peak of bone mass and thus greater latitude for the maintenance or skeletal integrity in the face of bone losses. Troeps skinfold thickness was a better predictor of total BMD and total BMC than was any other skinfold thickness. The study did not find a relationship between total BMD and body fat %, but total fat was significantly positively related to total BMD(r=0.49) and total BMC(r=0.60). It supports earlier report that there was a significant correlation between TBMD and body weight. Conclusively, total fat, lean body mass and pubertal development could influence BMD in pubescent girls. Clearly, longitudinal studies are required to assess the effect of puberty on peak bone mass, and to define further the potential determinants of peak bone mass.