• Journal of Preventive Medicine and Public Health
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• v.53 no.5
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• pp.371-380
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• 2020

Objectives: This study investigated the effects of socio-demographic factors on the decreasing trend in the sex ratio at birth from 1997 to 2017 in Korea. Methods: Data from 10 349 602 live births registered with Statistics Korea from 1997 to 2017 were analyzed. The secondary sex ratio (SSR), defined as the ratio of male to female live births, during the study period (1997-1999 [phase I], 2000-2002 [phase II], 2003-2005 [phase III], 2006-2008 [phase IV], 2009-2011 [phase V], 2012-2014 [phase VI], and 2015-2017 [phase VII]) was calculated according to selected socio-demographic factors, such as parental age, education, occupation, and birth order. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals for a male birth after adjusting for potential confounders. Results: The SSR gradually decreased from 1.10 (in 1998-2000 and 2002) to 1.05 (in 2013-2016). While a decreasing trend in the SSR was not noted among first births, male-biased sex ratios were prominent among third and higher-order births, for which the highest SSR was 1.46 in 1998. Higher birth order was significantly associated with an excess of male births in phases I-VI (≥third vs. first, OR range, 1.03 to 1.35). Advanced maternal age was significantly associated with an excess of female births in phases II, III, and V (≥40 vs. 20-24 years, OR range, 0.92 to 0.95). Conclusions: This study demonstrated that advanced maternal age and reduction of the artificially-biased SSR among third and higher-order births may partially explain the decreasing trend in the SSR from 1997 to 2017 in Korea.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.26 no.4
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• pp.251-257
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• 2015

Objectives : We compared the clinical presentations of manic and depressive episodes and the treatment response among children and adolescents with bipolar disorder (BD) types I and II and BD not otherwise specified (NOS). Methods : The sample consisted of 66 patients, aged between 6 and 18 years, who were admitted for BD to a 20-bed child and adolescent psychiatric ward in a university hospital located in Seoul, Korea. Results : Patients with BD type I were more likely to have lower intelligence quotients and exhibit violent behaviors during manic episodes than patients with BD type II or BD NOS and to show better treatment responses during manic episodes than patients with BD NOS. Patients with BD NOS were more likely to have an irritable mood rather than a euphoric mood during the manic phase than patients with BD type I or II and to exhibit violent behaviors during the depressive phase and chronic course than patients with BD type II. Conclusion : Pediatric BD patients are heterogeneous with respect to their clinical characteristics. Implications for the usefulness of the current diagnostic subtype categories should be investigated in future studies.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.51-65
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• 1999

The present review report introduces the existing analysis codes and physical modeling of two-phase flow associated with initiating event of HCDA in Liquid Metal Reactors for the effective study in the future, because the related research has not been systematically carried out in Korea compared with other areas. The description in this report is specifically addressed to the results yielded from careful review of the technical concepts on the two-phase flow modeling in the SAS2A code which was developed in ANL. The report is prepared in 2 parts based on the definite physical phenomena. The liquid slug and gas behavior models are main representations in the part (I) and (II), respectively. In this regard, it is expected that this report provide a fundamental knowledge on the two-phase flow model in LMR and, thus, contribute to establishment of the necessary HCDA analysis technology concerned with the LMR development in Korea.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.4 s.34
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• pp.65-74
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• 1999

We have studied the stability of W/O high internal phase emulsions(HIPE) containing water, cetyl dimethicone copolyol and oils varying magnesium sulfate in the range 0 to 0.5 wt% and oil polarities, respectively. The rheological consistency was mainly destroyed by the coalescence of the deformed water droplets. The greater the increase of complex modulus was, the less coalescence occurred and the more consistent the concentrated emulsions were. The increasing pattern of complex modulus versus volume fraction has been explained with the resistance to coalescence of the deformed interfacial film of water droplets in concentrated W/O emulsion. The stability is dependent on: (i) the choice of the oil is important, the requirements coincide with the requirements for the formation of the rigid liquid crystalline phases; and (ii) addition of salts the aqueous phase opposes the instability due to coalescence. Increasing the salt concentration increases the refractive index of the aqueous phase. It lowers the difference in the refractive index between the oil and aqueous phases. This decreases the attraction between the water domains, thus increasing the stability.

• Proceedings of the SCSK Conference
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• 1999.10a
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• pp.65-74
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• 1999

We have studied the stability of W/O high internal phase emulsions(HIPE) containing water, cetyl dimethicone copolyol and oils varying magnesium sulfate in the range 0 to 0.5wt% and oil polarities, respectively. The rheological consistency was mainly destroyed by the coalescence of the deformed water droplets. The greater the increase of concentrated modulus was, the less coalescence occurred and the more consistent the concentrated emulsions were. The increasing pattern of complex modulus versus volume fraction has been explained with the resistance to coalescence of the deformed interfacial film of water droplets in concentrated W/O emulsion. The stability is dependent on: (i) the choice of the oil is important, the requirements coincide with the requirements for the formation of the rigid liquid crystalline phases :5; and (ii) addition of salts the aqueous phase opposes the instability due to coalescence:. Increasing the salt concentration increases the refractive index of the aqueous phase. It lowers the difference in the refractive index between the oil and aqueous phases. This decreases the attraction between the water domains, thus increasing the stability.

• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.133-139
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• 2008

A new sensitive and selective spectrophotometric method for determination of trace amounts of cadmium using a polyvinyl chloride membrane containing bis-(2-ethylhexyl)phthalate as a solid phase extraction medium was investigated. Bis-(2-ethylhexyl)phthalate has used as a plasticizer. Cd(II) in an aqueous solution was trapped on the membrane in the form of colorful Cd (II)-I- - MG complexes (which MG is malachite green) and the cadmium complex was concentrated in the membrane. The absorbance of the green membrane was measured at 629 nm using a spectrophotometer, and then, the concentration of the cadmium was calculated using a calibration curve, which expressed the relationship between the Cd(II) concentration and the membrane absorbance after coloring for 25 min. The calibration curve was linear in the range of 10-760 μgL-1 cadmium in the test solution. The detection limit based on the 3Sbl criterion was 1.8199 μgL-1 and the relative standard deviations (RSD) were less than 4 % (n=5). The proposed method has been successfully applied to the determination of trace amounts of cadmium in the Tadjan River water sample (Sari-Iran), and the mean value of 28.7 μgL-1 was obtained.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.1
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• pp.1-8
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• 2011

The objective of this study was to determine the effectiveness of topical 5% EMLA cream versus 20% Benzocaine gel in reducing pain from intra oral needle insertion alone as well as injection of anesthetic. The 2 topical anesthetics were tested against each other bilaterally using a randomized, controlled, single blinded, split mouth design. Phase I was conducted to find out the rapidity of onset action of the two agents on anterior/posterior vestibules and anterior/posterior palatal mucosa. Phase II was conducted to evaluate the efficacy of the two topical anaesthetic agents in reducing the pain of intraoral injections. The agents were left in anterior/posterior vestibules and anterior/posterior palatal mucosa for the amount of time recorded in phase I. Subjects recorded pain on a 100-mm modified visual analog scale(VAS). A pulse oximeter was used to recorded the preoperative and postoperative pulse rates. In phase I of the study, two topical agents showed the longer onset of action at anterior part and vestibules than posterior part and palatal mucosa. EMLA cream showed the rapidest onset of action compared to benzocaine gel except on anterior palatal mucosa. In phase II of the study, the VAS grading of the pain for anesthetic administration showed EMLA cream was significantly(P<.05) better in elimination or reducing the pain on the anterior/posterior palatal mucosa. In conclusion, EMLA cream showed the rapidest onset of action compared to benzocaine gel except on anterior palatal mucosa. EMLA cream was found to be superior to Benzocaine gel with regards to pain reduction for anesthetic administration especially on anterior and posterior palatal mucosa.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.5
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• pp.481-490
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• 1999

To investigate the changes in the responses of vestibular neurons with time during vestibular compensation, the resting activity and dynamic responses of type I and II neurons in the medial vestibular nuclei to sinusoidal angular acceleration were recorded following unilateral labyrinthectomy (ULX) in Sprague-Dawley rats. The unitary extracellular neuronal activity was recorded from the bilateral medial vestibular nuclei with stainless steel microelectrodes of $3{\sim}5\;M{\Omega}$ before ULX, and 6, 24, 48, 72 hours, and 1 week after ULX under pentobarbital sodium anesthesia (30 mg/kg, i.p.). Gain (spikes/s/deg/s) and phase (in degrees) were determined from the neuronal activity induced by sinusoidal head rotation with 0.05, 0.1, 0.2, and 0.4 Hz. The mean resting activity before ULX was $16.7{\pm}8.6$ spikes/s in type I neurons $(n=67,\;M{\pm}SD)$ and $14.5{\pm}8.4$ spikes/s in type II neurons (n=43). The activities of ipsilateral type I and contralateral type II neurons to the lesion side decreased markedly till 24 hr post-op, and a significant difference between ipsilateral and contralateral type I neurons sustained till 24 hr post-op. The gain at 4 different frequencies of sinusoidal rotation was depressed in all neurons till 6 or 24 hr post-op and then increased with time. The rate of decrease in gain was more prominent in ipsilateral type I and contralateral type II neurons immediately after ULX. Although the gain of those neurons increased gradually after 24 hours, it remained below normal levels. The phase was significantly advanced in all neurons following ULX. These results suggest that a depression of activities in ipsilateral type I and contralateral type II neurons is closely related with the occurrence of vestibular symptoms and restoration of activities in those neurons ameliorates the vestibular symptoms.

• Journal of Korean Neurosurgical Society
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• v.58 no.2
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• pp.131-136
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• 2015

Objective : To investigate the incidence of corpus callosum injury (CCI) in patients with mild traumatic brain injury (TBI) using brain MRI. We also performed a review of the clinical characteristics associated with this injury. Methods : A total of 356 patients in the study were diagnosed with TBI, with 94 patients classified as having mild TBI. We included patients with mild TBI for further evaluation if they had normal findings via brain computed tomography (CT) scans and also underwent brain MRI in the acute phase following trauma. As assessed by brain MRI, CCI was defined as a high-signal lesion in T2 sagittal images and a corresponding low-signal lesion as determined by axial gradient echo (GRE) imaging. Based on these criteria, we divided patients into two groups for further analysis : Group I (TBI patients with CCI) and Group II (TBI patients without CCI). Results : A total of 56 patients were enrolled in this study (including 16 patients in Group I and 40 patients in Group II). Analysis of clinical symptoms revealed a significant difference in headache severity between groups. Over 50% of patients in Group I experienced prolonged neurological symptoms including dizziness and gait disturbance and were more common in Group I than Group II (dizziness : 37 and 12% in Groups I and II, respectively; gait disturbance : 12 and 0% in Groups I and II, respectively). Conclusion : The incidence of CCI in patients with mild TBI was approximately 29%. We suggest that brain MRI is a useful method to reveal the cause of persistent symptoms and predict clinical prognosis.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.183-187
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• 2005

Abstract The cancer chemopreventive potential of chitosanoligosaccharides was investigated by measuring the induction of quinone reductase and glutathione S-transferase activities and inhibition of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide I (1-${\kappa}$Da${\kappa}$Da) significantly induced glutathione S-transferase activity with a maximal 1.5-fold increase at 500 ${\mu}$g/ml, while chitosanoligosaccharide II (3-${\kappa}$Da${\kappa}$Da) (500 ${\mu}$g/ml) strongly induced quinone reductase (p<0.01) and glutathione S-transferase (p<0.005) activities. The in vitro incubation of rat liver microsomes with chitosanoligosaccharides I and II (2.5, 5, 50, and 500 ${\mu}$g/ml) showed a dose-dependent inhibiton of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide II was a more potent inhibitor of cytochrome P450 2B1 activity than chitosanoligosaccharide I. Accordingly, these findings suggest that chitosanoligosaccharides are potential chemopreventive agents.