• KDI Journal of Economic Policy
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• v.32 no.4
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• pp.1-34
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• 2010

We conduct a comprehensive risk analysis of household debt in Korea for the first time using the whole sample credit bureau (CB) data of 2.2 million individual debtors. After analysing debt service capacity profiles of debtor groups classified by the borrower characteristics such as income, age, occupation, credit scoring, and the type of creditor business companies, we investigate the impact of interest rate and income changes on debt service-to-income ratios (DTIs) and default rates of respective debtor groups. Empirical results indicate that debt service burdens are relatively high for low income wage earners, high income self-employed, low income capital and card loan holders, and high income mutual savings loan holders. We also find that debtors from multiple financial companies are particularly weak in their debt service capacity. The scenario analysis indicates that financial companies, with the current level of capital buffers, may be able to absorb negative consequences arising from the increase in DTIs and loan default rates if the interest rate and income changes remain modest. However, the negative consequences may fall disproportionately on non-bank financial companies such as capital, credit card, and mutual savings banks, whose debtors' DTIs are already high. We also find that the refinancing risk of household debt is relatively high in Korea as more than half of household mortgage debts are bullet loans. As the DTIs of mortgage loan holders are already high, under the current DTI regulation, mortgage loans may not be readily refinanced especially when the interest rate rises. Disruptions in mortgage loan refinancing may put downward pressure on housing prices, which may in turn magnify refinancing risk under the current loan-to-value (LTV) regulation. Overall our analysis suggests that, for more effective monitoring of household debt risk, it is necessary to combine existing surveillance schemes based on macro aggregate indicators with more comprehensive and detailed risk analyses based on micro individual data.

• Journal of the Korean Geographical Society
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• v.40 no.4 s.109
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• pp.428-440
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• 2005

There is currently no agreement among archaeologists, environmental historians, and paleoecologists as to the relative significance of pre- and post-Conquest human impact on the environments of Highland Mexico. This paper presents the results of pollen, microscopic charcoal, dung fungal spore, isotope, and magnetic susceptibility analyses on ca. 4m sediment core. The coring site is Hoya Rincon de Parangueo, one of the seven maar lakes in the Valle do Santiago. Amaranthaceae pollen, one of important disturbance indicators and Zea mays pollen obviously indicate two periods of agricultural activities. The first period begins ca. 400 B.C. and ends ca. A.D. 850. The second begins around A.D. 1550 and continues to the present. During the first period, the degree of agricultural activities was related to periodical sunspot cycles and the most intense activities were present between ca. A.D. 150-ca. A.D. 400. The abrupt increase of $\delta^{18}O$ around 280cm may reflect that an important transition to a dry phase took place around A.D. 450. People probably stopped cultivating crops due to dry conditions prevailing since ca. A.D. 450. The second period, the post-Conquest, exhibits a dramatic increase of sporormiella, dung fungal spores resulted fron the introduction of cattle. Low Poaceae frequency and charcoal production and high $\delta^{13}C$ values, magnetic susceptibility, and organic contents all indicate the arrival of the Spanish. Most importantly, it seems that mesquite (Prosopis juliflora) could have benefits from declined fire frequencies caused by cattle grazing. The study area is now entirely dominated by woody plants like mesquite, which clearly demonstrates that serious vegetation change occurred in the study area.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.421-429
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• 2007

Some researchers suggested that tactile sensor system would be useful in evaluating masticatory muscles of TMD patients, but there were few studies on the effects of chewing with time. The aim of this study was to investigate the change of elasticity and stiffness for masseter and temporal muscles of normal subjects before, during and after gum chewing and to obtain the baseline data for further researches on the elasticity and stiffness for masticatory muscles of TMD patients. Stiffness and elasticity of their anterior temporalis and inferior masseter muscle were measured bilaterally by a tactile sensor system. Each subject was instructed to sit on a chair for evaluation of masticatory muscles. Before operating the sensor, the thickest skin area over anterior temporalis and inferior masseter muscles were selected as the points to be pressed by a tactile sensor, and marked with a pen. While the teeth of subjects were lightly contacted, the probe of the tactile sensor was placed perpendicularly over the marked point over the skin, followed by computer-controlled movement including gently pressing straight down on the muscle for a second and retracting. All subjects were instructed to chew gum (Excellent Breath, Taiyo Co., Japan) bilaterally with a velocity of 2 times per second for 40 minutes after the first measurement had been performed for the baseline data of all subjects. The measurements had been repeated during chewing with 10 minutes of interval and continued for 40 minutes with same interval after chewing. Resultantly, the decrease of elasticity and the increase of stiffness in masticatory muscles can be seen significantly within 10 minutes after chewing and those were maintained during chewing without significant change with chewing time. The elasticity of muscles was recovered within 10 minutes after stopping chewing, but the stiffness was recovered more lately than elasticity by about 10 minutes. Based on these results, it can be concluded that elasticity and stiffness of muscles would be good indicators to evaluate the masticatory muscles objectively, when more supported by further researches.

• Korean Journal of Biological Psychiatry
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• v.9 no.2
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• pp.140-151
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• 2002

Object and Method:Minor physical anomalies(MPAs) are frequently seen in patients with schizophrenia. MPAs are considered to arise from the anomalous development of ectoderm-originated tissues in the developing fetus. Since the central nervous system originates from ectoderm, MPAs can be regarded as externally observable and objective indicators of the aberrant development which might have taken place in the central nervous system. To investigate whether MPAs are more frequent in schizophrenic patients, the frequencies of MPAs were compared between schizophrenic patients and normal controls. Total 245 schizophrenic patients diagnosed with DSM-IV(male : 158, female : 87), and 418 normal control subjects(male : 216, female : 202) were included in this study. The MPAs were measured using the modified Waldrop scale with fifteen items in six bodily regions; head, eye, ear, mouth, hand, and foot. Result:The total scores of Waldrop scale were $4.40{\pm}1.93$($mean{\pm}standard$ deviation) in patients and $3.43{\pm}1.68$ in controls for females, and for males, $4.58{\pm}1.75$ in patients and $4.28{\pm}1.59$ in controls. For females, the excess of MPAs in schizophrenic patients was statistically significant(t-test : p<0.001). For males, schizophrenic patients also showed more MPAs than normal controls, but this tendency did not reach statistical significance (t-test : p=0.094). When the modified Waldrop total scores excluding head circumference were compared, the total scores in schizophrenic patients were significantly higher for both male and female subjects(t-test : male p<0.001, female p=0.001). The individual anomaly items included in Waldrop scale were also investigated. The items of epicanthus, hypertelorism, malformed ears, syndactylia were significantly more frequent in schizophrenic patients. In contrast, the items of adherent ear lobes, asymmetric ears, furrowed tongue, curved fifth finger, single palmar crease and big gap between toes did not show any differences in frequency between schizophrenic patients and normal controls. Since a lot of statistical analyses showed different results between male and female subjects, it seems to be necessary to consider gender as an important controlling variable for the analysis, however only the item of head circumference showed statistically significant gender-related difference according to log-linear analysis. Conclusion:With a relatively large sample size, the frequencies of MPAs enlisted in Waldrop scale were compared between schizophrenic patients and normal controls in this study. MPAs were more frequently seen in schizophrenic patients and, especially, several specific items in the Waldrop scale showed prominent excess in schizophrenic patients. Although definite conclusions cannot be drawn due to the inherent limitation of the study using Waldrop scale, these results seem to support the possibility that aberrant neurodevelopmental process might be involved in the pathogenesis of schizophrenia in some of the patients.

• Clinical and Experimental Pediatrics
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• v.46 no.10
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• pp.977-982
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• 2003

Purpose : This study aimed to examine the excretion of various urinary proteins in children with a history of urinary tract infection(UTI), with or without vesicoureteral reflux(VUR) or reflux nephropathy, and to identify means of predicting the severity of VUR or the presence of reflux nephropathy as indicated by these markers, and to know how these markers are changed after resolution of VUR. Methods : We studied 30 children with previous UTI, without VUR and renal scarring(group I), 12 children with VUR, without evidence of renal scarring(group II), and 34 children with VUR and renal scarring(group III). 24-hour or 12-hour urine ${\beta}_2$ microglobulin(${\beta}_2$ MG), microalbumin and N-acetyl-${\beta}$-D-glucosaminidase(NAG) were measured in each child. Urinary protein excretions were analyzed according to the degree of VUR(mild VUR : a grade reflux I-III, severe VUR : a grade reflux IV-V). Cases of bilateral VUR were graded by the higher grade of reflux detected. A total of 46 children with primary VUR were followed. Among these patients, VUR was completely resolved in 16 children. Voiding cystourethrography(VCUG) and DMSA scan were performed every year. Values for urinary markers were estimated every year. Results : 24 or 12 hour urine microalbumin and NAG excretions were significantly increased in group III compared to group I(microalbumin : $27.7{\pm}26.0mg/gCr$ vs $15.0{\pm}10.7mg/gCr$, P<0.05, NAG : $15.2{\pm}18.7U/gCr$ vs $3.4{\pm}2.2U/gCr$, P<0.05). Urinary ${\beta}_2$ MG excretions were not significantly different between groups. Urinary NAG excretions were elevated in the group of children with severe VUR compared to mild VUR($26.8{\pm}27.1U/gCr$ vs $7.6{\pm}3.8U/gCr$, P<0.05). After resolution of VUR, urinary microalbumin and NAG excretions were decreased(P<0.05). Conclusion : Urinary microalbumin and NAG may be useful clinical indicators to predict the presence of reflux nephropathy and the resolution of VUR. Especially, urinary NAG excretions may be used as a possible method to predict the severity of VUR.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.3
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• pp.40-53
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• 2013

Most of the existing domestic studies to identify the distribution of longevity population and influencing factors oriented confirmatory approach. Furthermore, most of the studies in this research topic simply have used their own definition of spatial unit of analysis or employed arbitrary spatial units of analysis according to data availability. These research approaches can not sufficiently reflect the spatial characteristic of longevity phenomenon and exposed to the Modifiable Aerial Unit Problem(MAUP). This research performed the Exploratory Spatial Data Analysis(ESDA) to identify the spatial autocorrelation of the distribution of longevity population and investigated whether the modifiable areal unit problem in the aspect of scale effect using spatial population data in Korea. We used Si_Gun_Gu and Eup_Myeon_Dong as two different spatial units of regional longevity indicators measured. Then, we applied Getis-Ord Gi* to investigate the existence of spatial hot spots and cold spots. The results from our analysis show that there exist statistically significant spatial autocorrelation and spatial hot spots and cold spots of regional longevity at both Si_Gun_Gu and Eup_Myeon_Dong levels. This result implies that the modifiable areal unit problem does exist in the studies of spatial patterns of longevity population distribution. The demand for longevity researches would be increased inevitably. In addition, there were apparent differences for the global spatial autocorrelation and local spatial cluster which calculated different spatial units such as Si_Gun_Gu and Eup_Myeon_Dong and this can be seen as scale effect of MAUP. The findings from our analysis show that any study in this topic can mislead results when the modifiable areal unit problem and spatial autocorrelation are not explicitly considered.

• Reproductive and Developmental Biology
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• v.32 no.1
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• pp.27-31
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• 2008

This study was performed to investigate the correlations between steroids and TGF-${\beta}_1$ levels and delayed parturition in SCNT clone calving. The recipients pregnant by AI were used as control (AI-R). All AI-R were labored by natural delivery (n=5, day $284{\pm}0.71$ of pregnancy). The recipients pregnant by SCNT embryo (SCNT-R) showing no signs of delivery about 10 days after expected date were operated by Caesarean section (n=5, day 292). The blood and placentome samples were obtained and weighed at parturition. The concentrations of plasma progesterone (P4) and Estradiol-$17{\beta}$ (E2) were measured by radioimmunoassay (RIA). The levels of plasma and placental TGF-${\beta}_1$ levels were examined by ELISA. The placentomes from SCNT-R were overweight (p<0.05) compared to those of AI-R. The plasma P4 (p<0.01) level in SCNT-R at parturition was significantly higher compared to that of AI-R. In contrast, the plasma E2 level in the SCNT-R was significantly lower compared to that of AI-R (p<0.05). The plasma and placental TGF-${\beta}_1$ protein levels in the SCNT-R were significantly higher than those of AI-R at parturition, respectively (p<0.01). Based on these results, aberrant expressions of steroid hormones and high levels of plasma and placental TGF-${\beta}_1$ protein at parturition may be one of the key indicators on delayed parturition of SCNT clone calving.

• Clinical and Experimental Pediatrics
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• v.50 no.2
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• pp.170-177
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• 2007

Purpose : Clinicopathological features were investigated to clarify the outcome and prognostic indicators for patients with IgA nephropathy in Korean children. Methods : We reviewed the outcomes of 61 patients in whom IgA nephropathy was diagnosed before the age of 15 years from 1991 to 2005 and followed-up at least for one year. All patients were confirmed by renal biopsy. Results : After mean follow-up of 5.2 years from onset, 24 patients of 61 (39.3%) were in clinical remission at the last examination. Thirty patients (49.2%) had hematuria or mild proteinuria (<$1g/m^2/d$), five (8.2%) had severe proteinuria (${\geq}1g/m^2/d$), and two (3.3%) had chronic renal failure. By univariate analysis, initial presentation at onset and Haas classification were less concordant with outcome. Hypertension during follow-up, rather than hypertension at presentation, was significantly correlated with outcomes (P<0.01). Sixty percent of patients who had more than 20% of glomerular sclerosis or crescent progressed to severe proteinuria or chronic renal failure, as compared with 7.1% of those who did not (P<0.01). Conclusion : Prognosis of childhood IgA nephropathy had a relatively benign course during a mean follow-up of 5.2 years. Persistent hypertension during follow-up and more than 20% of glomerular sclerosis or crescent were strong predictors of a progressive course of IgA nephropathy. A new histologic classification according to characteristics of childhood IgA nephropathy must be established to assess prognosis. Further efforts should be made to understand the prognosis of IgA nephropathy through long-term follow-up.

• Clinics in Shoulder and Elbow
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• v.14 no.1
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• pp.13-19
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• 2011

Purpose: Not much is known about the obvious relationship between posteroinferior rotator cuff tear and biceps lesion. The purpose of this study is to analyze the effect of posteroinferior rotator cuff tear on a biceps lesions by comparing the rotator cuff tear and biceps lesions with the number of cuff tears and the degree of degeneration of the rotator cuff. Materials and Methods: 65 patients who underwent surgery for a posteroinferior rotator cuff tear from 2002 to 2009 were included as subjects. The study determined the factors (the number of cuff tears and the degree of degeneration as assessed by MRI) that affected biceps lesions and the kinematic stability of the rotator cuff. Results: Biceps lesion was noted 11 patients among the 51 patients with supraspinatus tendon tears and in 8 patients among the 14 patients with supraspinatus, infraspinatus or teres minor tendon tears, and there was a statistically significant difference between those two groups (p=0.0095). The number of cuff tears was proportional to biceps lesion with statistical significance (p=0.0095). Among the biceps lesions, SLAP II lesion showed a statistically different distribution according to the number of cuff tears (p=0.0073). The degeneration factors (Goutallier's classification and the tangent sign) had no correlations with biceps lesion. Conclusion: Posterosuperior cuff tear may affect biceps lesion. Especially, the number of cuff tears has a close relationship, but the degenerative indicators have no relationship with biceps lesion.

• Korean Journal of Remote Sensing
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• v.33 no.5_3
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• pp.855-866
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• 2017

Several research cases using remote sensing methods to analyze changes of storage and dynamics of groundwater aquifer were reviewed in this paper. The status of groundwater storage, in an area with regional scale, could be qualitatively inferred from geological feature, surface water altimetry and topography, distribution of vegetation, and difference between precipitation and evapotranspiration. These qualitative indicators could be measured by geological lineament analysis, airborne magnetic survey, DEM analysis, LAI and NDVI calculation, and surface energy balance modeling. It is certain that GRACE and InSAR have received remarkable attentions as direct utilization from satellite data for quantification of groundwater storage and dynamics. GRACE, composed of twin satellites having acceleration sensors, could detect global or regional microgravity changes and transform them into mass changes of water on surface and inside of the Earth. Numerous studies in terms of groundwater storage using GRACE sensor data were performed with several merits such that (1) there is no requirement of sensor data, (2) auxiliary data for quantification of groundwater can be entirely obtained from another satellite sensors, and (3) algorithms for processing measured data have continuously progressed from designated data management center. The limitations of GRACE for groundwater storage measurement could be defined as follows: (1) In an area with small scale, mass change quantification of groundwater might be inaccurate due to detection limit of the acceleration sensor, and (2) the results would be overestimated in case of combination between sensor and field survey data. InSAR can quantify the dynamic characteristics of aquifer by measuring vertical micro displacement, using linear proportional relation between groundwater head and vertical surface movement. However, InSAR data might now constrain their application to arid or semi-arid area whose land cover appear to be simple, and are hard to apply to the area with the anticipation of loss of coherence with surface. Development of GRACE and InSAR sensor data preprocessing algorithms optimized to topography, geology, and natural conditions of Korea should be prioritized to regionally quantify the mass change and dynamics of the groundwater resources of Korea.