• Archives of Craniofacial Surgery
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• v.23 no.3
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• pp.103-110
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• 2022

Background: The primary objectives of mandibular surgery are to achieve optimal occlusion, low sensory disturbance, and adequate fixation with early movement. In-depth knowledge of the mandibular structure is required to achieve these goals. This study used computed tomography (CT) to evaluate the mandibular cortical thickness and cancellous space according to age and sex. Methods: We enrolled 230 consecutive patients, aged 20 to 50 years, who underwent CT scanning. The cortex and cancellous space centered around the inferior alveolar nerve (IAN) canal were measured at two specific locations: the lingula and second molar region. Statistical analysis of differences according to increasing age and sex was performed. Results: The t-test revealed that the cancellous space and cortical thickness differed significantly with respect to the threshold of 35 years of age. Both cortical thickness and cancellous space in the molar region were negatively correlated with age. Meanwhile, both cortical thickness and cancellous space in the lingula region showed a positive correlation with age. With respect to sex, significant differences in the cancellous space at the molar region and the cortical thickness at the lingula were observed. However, no further statistically significant differences were observed in other variables with respect to sex. The sum of each measurement on the mandibular body reflected the safe distance from the surface of the outer cortex to the IAN canal. The safe distances also showed statistically significant differences between those above and below 35 years of age. Conclusion: Knowledge of the anatomical structure of the mandible and of changes in bone structure is crucial to ensure optimal surgical outcomes and avoid damage to the IAN. CT examination is useful to identify changes in the bone structure, and these should be taken into account in the planning of surgery for older patients.

• Journal of Audiology & Otology
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• v.25 no.3
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• pp.163-170
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• 2021

Cortical deafness is a clinical rarity whereby a patient is unresponsive to all types of sounds despite the preserved integrity of the peripheral hearing organs. In this study, we present a patient who suddenly lost his hearing following ischaemic infarcts in both temporal lobes with no other neurological deficits. The CT confirmed damage to the primary auditory cortex (Heschl's gyrus) of both hemispheres. Initially, the patient was unresponsive to all sounds, however, he regained some of the auditory abilities during 10 months follow up. Pure tone threshold improvement from complete deafness to the level of moderate hearing loss in the right ear and severe in the left was observed in pure tone audiometry. Otoacoustic emissions, auditory brainstem responses, and acoustic reflex findings showed normal results. The middle and late latency potential results confirmed objectively the improvement of the patient's hearing, however, after 10 months still, they were somewhat compromised on both sides. In speech audiometry, there was no comprehension of spoken words neither at 3 nor at 10 months. The absent mismatch negativity confirmed above mentioned comprehension deficit. The extensive auditory electrophysiological testing presented in this study contributes to the understanding of the neural and functional changes in cortical deafness. It presents the evolution of changes after ischaemic cerebrovascular event expressed as auditory evoked potentials starting from short through middle and long latency and ending with event-related potentials and supported by neuroimaging.

• Korean Journal of Audiology
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• v.25 no.3
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• pp.163-170
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• 2021

Cortical deafness is a clinical rarity whereby a patient is unresponsive to all types of sounds despite the preserved integrity of the peripheral hearing organs. In this study, we present a patient who suddenly lost his hearing following ischaemic infarcts in both temporal lobes with no other neurological deficits. The CT confirmed damage to the primary auditory cortex (Heschl's gyrus) of both hemispheres. Initially, the patient was unresponsive to all sounds, however, he regained some of the auditory abilities during 10 months follow up. Pure tone threshold improvement from complete deafness to the level of moderate hearing loss in the right ear and severe in the left was observed in pure tone audiometry. Otoacoustic emissions, auditory brainstem responses, and acoustic reflex findings showed normal results. The middle and late latency potential results confirmed objectively the improvement of the patient's hearing, however, after 10 months still, they were somewhat compromised on both sides. In speech audiometry, there was no comprehension of spoken words neither at 3 nor at 10 months. The absent mismatch negativity confirmed above mentioned comprehension deficit. The extensive auditory electrophysiological testing presented in this study contributes to the understanding of the neural and functional changes in cortical deafness. It presents the evolution of changes after ischaemic cerebrovascular event expressed as auditory evoked potentials starting from short through middle and long latency and ending with event-related potentials and supported by neuroimaging.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.4
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• pp.277-283
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• 2020

Objective: The sperm DNA fragmentation index (DFI) guides the clinician's choice of an appropriate assisted reproductive technology (ART) procedure. The DFI can be determined using commercially available methodologies, including sperm chromatin dispersion (SCD) kits and sperm chromatin structure assay (SCSA). Currently, when DFI is evaluated using SCD kits, the result is analyzed in reference to the SCSA-derived threshold for the choice of an ART procedure. In this study, we compared DFI values obtained using SCSA with those obtained using SCD and determined whether the difference affects the choice of ART procedure. Methods: We compared SCSA to two SCD kits, CANfrag (n=36) and Halosperm (n=31), to assess the DFI values obtained, the correlations between tests, the technical repeatability, and the impact of DFI on the choice of ART. Results: We obtained higher median DFI values using SCD kits than when using SCSA, and this difference was significant for the CANfrag kit (p<0.001). The SCD kits had significantly higher coefficients of variation than SCSA (p<0.001). In vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) would be chosen for a significantly higher proportion of patients if a decision were made based on DFI derived from SCD rather than DFI determined using SCSA (p=0.003). Conclusion: Our results indicate that SCD kit-specific thresholds should be established in order to avoid the unnecessary use of IVF/ICSI based on sperm DNA damage for the management of infertility. Appropriate measures should be taken to mitigate the increased variability inherent to the methods used in these tests.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.6
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• pp.1291-1307
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• 2021

State-sponsored cyberattacks have increased significantly and threaten national security in recent years. State-sponsored cyberattacks are often more sophisticated and destructive that attacks by individuals and private groups because of the concentration of manpower and resources. So major countries including the United States and the United Kingdom, as well as international organizations such as the EU and OECD, are recommending proportional response measures against cyberattacks. The Republic of Korea(ROK) is also trying to change its will to secure cyberattack deterrence and prepare active response through the 「National Cybersecurity Strategy 2019」. However, the ROK is not equipped with an adequate methodology to assess the severity of cyberattacks nor measures for proportional response to such attacks. In this paper, we propose a Cyber Attack Severity Assessment(CASA) methodology that can assess the scale and impact of damage to prepare external response threshold for cyberattacks at the government-level and to enable proportional responses when responding.

• Current Optics and Photonics
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• v.6 no.2
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• pp.143-150
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• 2022

Anti-resonant hollow-core photonic crystal fiber (AR-HCF) has unique advantages, such as low nonlinearity and high damage threshold, which make it a promising candidate for high-power laser delivery at distances of tens of meters. However, due to the special structure, optical properties such as mode-field profile and bending loss of hollow-core fibers are different from those of solid-core fibers. These differences have limited the widespread use of AR-HCF in practice. In this paper we conduct numerical analysis of AR-HCFs with different structural parameters, to analyze their influences on an AR-HCF's optical properties. The simulation results show that with a 23-㎛ air-core diameter, the fundamental mode profile of an AR-HCF can well match that of the widely used Nufern's 20/400 fiber, for nearly-single-mode power delivery applications. Moreover, with the ratio of cladding capillary diameter to air-core diameter ranging from 0.6 to 0.7, the AR-HCF shows excellent optical characteristics, including low bending sensitivity while maintaining single-mode transmission at the same time. We believe these results lay the foundation for the application of AR-HCFs in the power delivery of high power fiber laser systems.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.1
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• pp.129-136
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• 2022

Purpose : The purpose of this study was to investigate the effect of applying intensity on the muscle activity and muscle hardness of the upper trapezius muscle in adult males when TENS (transcutaneous electrical nerve stimulation) was applied. In addition, this study intends to prepare the scientific basic data of TENS for the purpose of relaxation based on the experimental results. Methods : Eighty-seven healthy adult males participated in the experiment, and they were randomly divided into an experimental group and a control group. All subjects in this study were healthy subjects without musculoskeletal or nervous system damage. All subjects were subjects who voluntarily consented to the purpose and method of the experiment. All subjects were provided with a load by typing for 20 minutes, and muscle activity and muscle hardness of the upper trapezius muscle were measured immediately. Afterwards, TENS was given to each groups for 15 minutes, and the experimental group received stimulation at the motor threshold level, and the control group received a placebo stimulation. After stimulation, muscle activity and muscle hardness of the upper trapezius muscle were measured in the same method. The measured data were compared between groups through an independent t-test and dependent t-test. The statistical significance level was set at .05. Results : The application of TENS statistically significantly decreased the muscle activity and muscle hardness of the trapezius muscle in the experimental group, and the results showed a significant difference from the control group. Conclusion : Application of TENS significantly decreased the muscle activity and muscle stiffness of the upper trapezius muscle. The application of TENS of applying intensity that induces muscle contraction may induce relaxation by reducing the muscle activity and muscle hardness of the trapezius muscle.

• Korean Journal of Acupuncture
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• v.39 no.4
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• pp.132-141
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• 2022

Objectives : Some acupoints are commonly utilized to treat a variety of diseases. The acupoints appear to have a wide range of effects caused by several mechanisms. The purpose of this study is to investigate into the potential role of microRNAs (miRNAs) in the multipotent effects of individual acupoint stimulation. Methods : We examined the miRNA expressions in the dorsal root ganglia (DRG) of neuropathic or inflammatory pain rats following ST36 and GB34 electroacupuncture (EA) stimulation. Neuropathic pain was induced by L5 spinal nerve ligation. Inflammatory pain was induced by knee joint injection of Complete Freund's adjuvant (CFA). EA was given under gaseous anesthesia with the same parameters (1mA, 2Hz, 30 min) in 5 consecutive days. Pain behaviors and miRNA expressions were analyzed. Results : In rats with neuropathic and inflammatory pain, EA treatments significantly enhanced the paw withdrawal threshold and weight-bearing force. After nerve injury, 36 miRNAs were upregulated in the DRG of neuropathic rats, while EA downregulated 10 of them. Furthermore, 14 miRNAs were downregulated following nerve damage, while one was increased by EA. 15 miRNAs were increased in the DRG of inflammatory rats following CFA injection, while 5 were downregulated by EA. Furthermore, 17 miRNAs were downregulated following CFA injection, while 7 were increased by EA. The miRNAs rno-miR-335, rno-miR-381-5p, rno-miR-1306-3p, and rno-miR-1839-3p were regulated by EA in both models. Conclusions : In two pain models, EA applied to ST36 and GB34 regulated miRNA expression differently. There appeared to be both acupoint-specific and non-specific miRNAs, and miRNA regulation of differential protein expression may modulate a variety of EA mechanisms.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.18-27
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• 2023

In this paper, the structural-thermal-optical performance analysis of the mirror was performed by setting the laser heat source as the boundary condition of the thermal analysis. For the laser heat source model, the Beer-Lambert model considering semi-transparent optical material based on Gaussian beam was selected as the boundary condition, and the mechanical part was not considered, to analyze the performance of only the mirror. As a result of the thermal analysis, thermal stress and thermal deformation data due to temperature change on the surface of the mirror were obtained. The displacement data of the surface due to thermal deformation was fitted to a Zernike polynomial to calculate the optical performance, through which the performance of the mirror when a high-energy laser was incident on the mirror could be predicted.

• Korean Journal of Radiology
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• v.22 no.7
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• pp.1142-1151
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• 2021

Objective: To evaluate microstructural damage in high myopia (HM) patients using 3T diffusion kurtosis imaging (DKI). Materials and Methods: This prospective study included 30 HM patients and 33 age- and sex-matched healthy controls (HCs) with DKI. Kurtosis parameters including kurtosis fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) as well as diffusion metrics including FA, mean diffusivity, axial diffusivity (AD), and radial diffusivity derived from DKI were obtained. Group differences in these metrics were compared using tract-based spatial statistics. Partial correlation analysis was used to evaluate correlations between microstructural changes and disease duration. Results: Compared to HCs, HM patients showed significantly reduced AK, RK, MK, and FA and significantly increased AD, predominately in the bilateral corticospinal tract, right inferior longitudinal fasciculus, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and left thalamus (all p < 0.05, threshold-free cluster enhancement corrected). In addition, DKI-derived kurtosis parameters (AK, RK, and MK) had negative correlations (r = -0.448 to -0.376, all p < 0.05) and diffusion parameter (AD) had positive correlations (r = 0.372 to 0.409, all p < 0.05) with disease duration. Conclusion: HM patients showed microstructural alterations in the brain regions responsible for motor conduction and vision-related functions. DKI is useful for detecting white matter abnormalities in HM patients, which might be helpful for exploring and monitoring the pathogenesis of the disease.