• Toxicological Research
• /
• v.29 no.2
• /
• pp.115-120
• /
• 2013

To investigate the effects of short-term exposure of beryllium on the human immune system, the proportion of T-lymphocytes such as CD3+, CD4+, CD8+, CD95, and NK cells, and the proportion of B cells and $TNF{\alpha}$ level in peripheral blood and immunoglobulins in the serum of 43 exposed workers and 34 healthy control subjects were studied. External exposure to beryllium was measured by atomic absorption spectrometer as recommended by the NIOSH analytical method 7300. T lymphocyte subpopulation analysis was carried out with flow cytometer. The working duration of exposed workers was less than 3 months and the mean ambient beryllium level was $3.4{\mu}g/m^3$, $112.3{\mu}g/m^3$, and $2.3{\mu}g/m^3$ in molding (furnace), deforming (grinding), and sorting processes, respectively (cited from Kim et al., 2008). However, ambient beryllium level after process change was non-detectable (< $0.1{\mu}g/m^3$). The number of T lymphocytes and the amount of immunoglobulins in the beryllium-exposed workers and control subjects were not significantly different, except for the total number of lymphocytes and CD95 (APO1/FAS). The total number of lymphocytes was higher in the beryllium-exposed individuals than in the healthy control subjects. Multiple logistic regression analysis showed lymphocytes to be affected by beryllium exposure (odd ratio = 7.293; p<0.001). These results show that short-term exposure to beryllium does not induce immune dysfunction but is probably associated with lymphocytes proliferation.

• Journal of Preventive Medicine and Public Health
• /
• v.44 no.3
• /
• pp.118-124
• /
• 2011

Objectives: Although cigarette smoking is known to be related to the exacerbation of asthma symptoms, several studies have indicated that the prevalence of cigarette smoking among asthmatic adolescents is similar to or even higher than that among non-asthmatic adolescents. The aim of this study was to evaluate the relationship between asthma and cigarette use behaviors and whether or not the presence of suicidal ideation modifies this relationship among Korean adolescents. Methods: We analyzed data from the 2008 Korea Youth Risk Behavior Web-based Survey, which included a nationally representative sample of middle and high school students. Multiple logistic regression models were used to calculate odd ratios and 95% confidence intervals of cigarette use behaviors among current asthmatics, former asthmatics, and nonasthmatics, after adjusting for gender, grade, school records, socioeconomic status, current alcohol use, and suicidal ideation. Results: Of 75 238 study participants, 3.5% were current asthmatics and 4.5% were former asthmatics. Compared with non-asthmatics, asthmatics were more likely to report current cigarette use, frequent and heavy cigarette use, and cigarette use before 13 years of age. There were statistically significant interactions between asthma and suicidal ideation in cigarette use behaviors. Conclusions: This study demonstrated that asthmatic adolescents are more likely than non-asthmatic adolescents to engage in cigarette use behaviors and the presence of suicidal ideation is an effect modifier of the relationship between asthma and cigarette use behaviors. Particular attention should be paid to the awareness of health risks of cigarette smoking and mental health problems among asthmatic adolescents.

• Journal of the Korean Society of Physical Medicine
• /
• v.8 no.4
• /
• pp.549-558
• /
• 2013

PURPOSE: This study is designed as a retrospective study, and identified the clinical usability of Sit to Stand (STS) test for predicting of fall incidence in stroke patients who experienced a fall within 1 year. METHODS: Between July 2011 and November 2012, 69 inpatients with stroke in K rehabilitation hospital were participated under voluntarily signing the informed consent form. STS test and 10m walk test (10MWT) were used to assess the muscle strength of lower-extremity and walking velocity, respectively. Also, we tested dynamic balance and motor function of lower-extremity in affected-side using with the Berg balance scale (BBS) and the Fugl-Meyer assessment of lower extremity (FM-L/E). METHODS: There were significant differences between subjects with fall-experienced group and without subjects without fall-experienced group in STS test, 10MWT, BBS scores and FM-L/E. STS test significantly showed a negative correlation between 10MWT (r=-.657), BBS (r=-.512), and FM-L/E (r=-.563). And, 10MWT have a influence on the performance of STS test (the capacity of explanation = 20%). The cut-off value of STS performance predicting falls experience is ${\geq}14.36$ seconds (sensitivity=76%; specificity=79%, area under curve=.785). According to logistic regression analysis of falls experience, subjects ${\geq}14.36$ s showed that 4.164 times (odd ratio) increased in falls than subjects < 14.36 s in STS test. CONCLUSION: This study demonstrated that STS test may be a useful tool predicting and measuring falls in patients with stroke. Further study will be needed to elucidate the kinematic analysis of STS test and the relationship between physical activity level and falls in stroke patients.

• Tribology and Lubricants
• /
• v.33 no.3
• /
• pp.85-91
• /
• 2017

This work studies the flow behaviors in the gap between the friction pad and separator in wet-clutch systems. The fluid volume of the lubricant is modeled using the entire system of wet-clutch pack of a dual clutch transmission that has larger outer radius of odd gear shifts and smaller inner radius of even gear shifts. Flow behaviors in the gap of the clutch pad are computed using the gear shift modes that consider the real relative velocities between the friction pad and separator. Flow behaviors in the gap of the disengaged clutch pad are mainly investigated for the wet-clutch system, whereas the engaged clutch pad is modeled with no fluid rate through the contacting surfaces. The developed hydrodynamic fluid pressures and velocity fields in the clutch pad gap are computed to obtain the relevant information for managing flow rates in wet-clutch packs under dual operating conditions during gear shifts. These hydrodynamic pressures and velocity fields are compared on the basis of each gear level and gap location, which is necessary to determine the effects of groove patterns on the friction pad. Shear stresses in the gap locations are also computed on the basis of the gear level for the inner and outer clutch pads. The computed results are compared and used for the design of cooling capacity against frictional heat generation in wet-clutch pack systems.

• Communications of the Korean Mathematical Society
• /
• v.32 no.1
• /
• pp.193-200
• /
• 2017

Given a pair p, q of relative prime positive integers, we have uniquely determined positive integers x, y, u and v such that vx-uy = 1, p = x + y and q = u + v. Using this property, we show that$${\sum\limits_{1{\leq}i{\leq}x,1{\leq}j{\leq}v}}\;{t^{(i-1)q+(j-1)p}\;-\;{\sum\limits_{1{\leq}k{\leq}y,1{\leq}l{\leq}u}}\;t^{1+(k-1)q+(l-1)p}$$ is the Alexander polynomial ${\Delta}_{p,q}(t)$ of a torus knot t(p, q). Hence the number $N_{p,q}$ of non-zero terms of ${\Delta}_{p,q}(t)$ is equal to vx + uy = 2vx - 1. Owing to well known results in knot Floer homology theory, our expanding formula of the Alexander polynomial of a torus knot provides a method of algorithmically determining the total rank of its knot Floer homology or equivalently the complexity of its (1,1)-diagram. In particular we prove (see Corollary 2.8); Let q be a positive integer> 1 and let k be a positive integer. Then we have $$\begin{array}{rccl}(1)&N_{kq}+1,q&=&2k(q-1)+1\\(2)&N_{kq}+q-1,q&=&2(k+1)(q-1)-1\\(3)&N_{kq}+2,q&=&{\frac{1}{2}}k(q^2-1)+q\\(4)&N_{kq}+q-2,q&=&{\frac{1}{2}}(k+1)(q^2-1)-q\end{array}$$ where we further assume q is odd in formula (3) and (4). Consequently we confirm that the complexities of (1,1)-diagrams of torus knots of type t(kq + 2, q) and t(kq + q - 2, q) in [5] agree with $N_{kq+2,q}$ and $N_{kq+q-2,q}$ respectively.

• Nutrition Research and Practice
• /
• v.14 no.2
• /
• pp.152-159
• /
• 2020

BACKGROUND/OBJECTIVES: Hypertriglyceridemia may be a more important predictor of cardiovascular disease in Asian population consuming carbohydrate-rich foods than in Western populations. Dairy products are known to play a beneficial role in obesity, dyslipidemia, and metabolic syndrome, but the results vary depending on gender and obesity. In this study, we investigated the associations between dairy product intake and hypertriglyceridemia in Korean adults. SUBJECTS/METHODS: The participants were selected from the Korea National Health and Nutrition Examination Survey 2007-2012 (KNHANES IV and V). A total of 22,836 participants aged 19-64 years were included in the analysis. A food frequency questionnaire used to determine the frequency of consumption of products (milk and yogurt). Multivariable logistic regression was used to assess the associations between dairy product intake and hypertriglyceridemia. RESULTS: A significantly decreased risk of hypertriglyceridemia was detected in the highest dairy product intake frequency group (≥ 1 time/day) (odd ratio [OR] = 0.79; 95% confidence interval [CI] 0.64-0.97, P for trend = 0.022) compared to that for the lowest dairy product intake frequency group. Among obese participants, the group with the highest intakes of milk (in men, OR = 0.64; 95% CI: 0.46-0.91, P for trend = 0.036) and yogurt (in women; OR = 0.53; 95% CI: 0.29-0.94, P for trend = 0.019) showed inverse associations with hypertriglyceridemia. No associations were detected in normal weight participants. CONCLUSION: The association between dairy product intake and hypertriglyceridemia differed by gender and obesity status. Further prospective studies are needed to confirm these associations.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.5
• /
• pp.2092-2099
• /
• 2013

Through the data transfer race in industry since 1990s, the operational speed of optical disk drive(ODD) becomes commonly over 10,000 rpm. Such high speed operation inevitably causes the vibration, which is also the disturbances in the read-write process of pick-up servo-controller. Generally the vibration disturbance problem can be solved by the vibration isolation using the rubber mount and the increase of robustness of the pick-up servo-controller. Optical disk itself has not been targeted for the vibration reduction, because it is manufactured under the standardized format. In this paper we focused on the increase of critical speed of optical disk, that is, the improvement of dynamic characteristics, with the control of residual stresses which are come from the injection molding process. To do this, first, the residual stresses induced from the injection molding process are calculated using finite element method. The major design parameters of the process conditions are flow rate and melt temperature, which control the residual stresses in optical disk. Second, the critical speed of optical disk is calculated with modal analysis considering residual stress distributions. It was found out that the critical speed can be improved by the control of operational parameters in the injection molding process.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.4
• /
• pp.860-868
• /
• 2011

Feistel and SPN are the two main structures in a block cipher. Feistel is a symmetric structure which has the same structure in encryption and decryption, but SPN is not a symmetric structure. In this paper, we propose a SPN block cipher so called SSB which has a symmetric structure in encryption and decryption. The proposed SSB is composed of the even numbers of N rounds. Each round consists of a round key addition layer, a subsitution layer, a byte exchange layer and a diffusion layer. The subsitution layer of the odd round is inverse function of one of the even round. And the diffusion layer is a MDS involution matrix. The differential and linear attack probability of SSB is $2^{-306}$ which is same with AES. The proposed symmetric SPN block cipher SSB is believed to construct a safe and efficient cipher in Smart Card and RFID environments which is in limited hardware and software resources.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.4
• /
• pp.661-668
• /
• 2012

A coaxial-cable impedance transformer that can be used in high power and wideband frequency range is an arbitrary impedance transformation ratio by an additional coaxial cable. The coaxial-cable impedance transformer to be 50-${\Omega}$ to 25-${\Omega}$ impedance transformation ratio is easily operated an wideband power divider by connecting two 50-${\Omega}$ lines at 25-${\Omega}$ impedance point. This wideband power divider has a poor output matching characteristic and a poor isolation characteristic between two output ports. In this paper, it proposes a coaxial-cable power divider to be a good output matching and isolation characteristics as it uses the singly terminated filter design theory. The odd-mode operation characteristic of the suggested power divider to use singly terminated low pass filter coefficient due to matching order and ripple value is examined by ADS program. And, it fabricates and measures the operation characteristic of 2-way power divider with 2nd-order and 4th-order matching circuit.

• Journal of Korean Ophthalmic Optics Society
• /
• v.12 no.3
• /
• pp.27-33
• /
• 2007

This research investigated the effects of spherical and aspherical R.G.P lenses which was performed by optometrists in In-Cheon and Kyung-Gi region. This research survey included various questions such as the fitting status, after-care method, preliminary test. Results of the survey revealed that the optometriests sold the asperical and spherical lenses with a ratio of 7:3, respectively, and most of them did not cheked Topography, Fluorescein test by slit lamp biomicroscope, Tear Break up time test, Schirmer test and so on. And, with fitted R.G.P lenses symptoms like light odd-feeling, congestion, eye-stimulus, dimness and dryness were frequently reported. The purposes of this study are to search for the ideal fitting check of R.G.P lens and remind the most important preliminary test for contact lens fitting.