• The Journal of Engineering Geology
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• v.18 no.4
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• pp.423-431
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• 2008

In general, water-saturated silt or clay alluvium is characterized with relatively low-resistivity. Thus we often encountered the problem that such a low-resistivity layer is misguided to be good aquifer of high-permeability and low-resistivity in the development of groundwater. This research was conducted with an emphasis on the identification of saturated silt or clay layer from the aquifer by performing the laboratory experiment of IP and resistivity methods on the various materials consisting of alluvium aquifer. Silt or clay layer is found to be characterized with the higher chargeability zone, compared to the sand layer. Regarding the mixture of sand and clay, the higher clay volume, the lower resistivity and the higher chargeability. Subsequently chargeability decreases.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.295-310
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• 2022

The Weolaksan and Sokrisan granites yield high SiO₂ and alkali (Na₂O+K₂O) contents and low CaO and P₂O₅ contents. The Al saturation index is ≥1.3, which indicates that the granites are peraluminous. The mean U and Th contents are 8.3 and 39.3 ppm, respectively, higher than typical Mesozoic granites in South Korea and about twice the global mean for granitic rocks. The causes of such high radioelement contents are related to high degrees of fractionation and the crustal origin of the granites. U- and Thbearing radioactive minerals occur in the granites include zircon, thorite, monazite, xenotime, fergusonite and uraninite. The fact that the mean Th/U ratio of the granites (5.4) is similar to the global average crustal value suggests that the radioelement contents of granite were controlled by the crustal source material. Given the correlation of Zr, Y, and heavy rare earth elements for U and Th, radioelements are more likely hosted by xenotime than zircon and monazite.

• Journal of Chest Surgery
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• v.29 no.5
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• pp.495-503
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• 1996

The bidirectional cavopulmonary shunt may be useful as an intermediate procedure before Fontal oper- ation in high-risk patients, because it provides adequate relief of cyanosis and relief of ventricular volume overload. But there are no established theory about the effects of bidirectional cavopulmonary shunt on pulmonary arterial development. The purpose of this article is a study of changes of pulmonary artery size after bidirectional cavopulmonary shunt. Ca diac catheterization and angiography procedures were done on 19 patients who underwent bidirectional cavopulmonary shunt from February 1992 to July 1994, their results were reviewed. Preoperative cardiac catheterization and angiography procedures were performed at a mean interval of ).8 $\pm$4.8($\pm$SEM) months before surgery and following catheterization at a mean postoperative interval of 19.6 $\pm$4.8 months. Pulmonary arterial sixte measurement were standardized for body surface area(Pulmon- arty artery index), and for diameter of descending thoracic aorta(McGoon ratio). Patient's age, body stir- face area, pulmonary angioplasty, preoperative McGoon ratio and follow-up intervals were considered as variables. Before bidirectional cavopulmonary shunt, patient's mean age, body surface area, arterial 02 saturation, diameter of right pulmonary artery, diameter of left pulmonary artery, pulmonary artery Index, McGoon ratio were 13.7$\pm$15.6 months, 0.40$\pm$0.12m2, 71.4$\pm$12.4m2, 7.1$\pm$1.7mm, 6.2$\pm$1 , 191.8$\pm$82.7mm21m2, 1.73 $\pm$0.49, respectively. After bidirectional cavopulmonary shunt, the values were changed to 39.9 $\pm$ 16.2 months, 0.58$\pm$0.07 m2, 83.0$\pm$3.8m2, 9.0$\pm$ 1.5 mm, 7.7$\pm$2.0, 197.3$\pm$57.1 mm2/m2, 1.76$\pm$0.32, respect- ively With patients'development (age, body surf'ace area), diameters of pulmonary arteries were increased, but pulmonary artery indices and McGoon ratios were not changed. And there were no effects of age, body surf'ace area, amount of increased 02 saturation, pulmonary angiography and follow-up duration on the increment of pulmonary ar- tery size. But when the McGoon ratio was as low as 1.2, there were significant increase in postoperative pulmonary artery sizes. There was a significant correlation between preoperative pulmonary artery index (PAI) and McGoon ratio (MGR) ; PAI : MGRxl18.0-12.4 In conclusion, bidirectional cavopulmonary shunt provides adequate increment of arterial 02 saturation and does not increase the pulmonary artery size. Further investi ation is mandatory to evaluate the effect of pulsatile bidirectional cavopulmonary shunt on pulmonary artery growth.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.597-605
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• 2013

This study was conducted in warty sea squirt farm, Jindong Bay(10 stations; July, October, January, April) for the culture period of Styela clava, Styela plicata. We utilized water temperature, chlorophyll a, suspended particulate matter, hydrodynamics, salinity and dissolved oxygen saturation for the suitability assessment of warty sea squirt farm. Newly, Life Requisite Suitability graphs were made for the correlation between the growth of Styela clava, Styela plicata and farm environment. As a result of the assessment for Habitat Suitability Index, western bay(HSI 0.32~0.41) show values higher than eastern bay(HSI 0.19~0.27). This result shows the high correlation with the unit production of Styela clava, Styela plicata($R^2$=0.834, P<0.01). This could be helpful for fishery management for the sustainable productivity through the scientific suitable site assessment.

• Journal of the Korean GEO-environmental Society
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• v.19 no.1
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• pp.15-23
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• 2018

In this study we performed risk evaluation based on parameters using the SINMAP, GIS-based extended program in order to predict ground disaster that is frequent recently. As for the risk evaluation, in order to understand the effects of parameters, we defined that the ranges of internal friction angles and T/R values as important variables had three and four patterns, respectively. The results of the interpretation were compared with those of the existing landslide in order to identify landslide flow and to evaluate the applicability of the parameters. The analysis of the geomorphologic saturated zone showed that the boundary saturated zone and the saturated zone were almost consistent with the site of avalanche of earth and rocks and the area of underground water convergence was correlated to the area where collapse started, indicating that the geomorphologic saturated zone may serve as an index for estimating possibility of landslide when used with slope distribution, colluvial soil, and structures inducing landslide in combination. When the lower limit of the internal friction angle increased more, the upper threshold decreased by 50 to 70% and the influence on the stability index was higher, but the influence was declined within the range of lower wetness index. The analysis of changes based on wetness index range showed that all the groups have similar SI distribution, except for the one in which mean altitude values are applied, indicating that the results are susceptible more by the internal friction angle than by the wetness index.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.45-58
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• 2012

For the development of reference values and evaluation of water quality in various environmental conditions, we divided the coastal region around Korean peninsular into 5 distinctive ecological regions based on the influence of surface current, depth, tidal range, turbidity, and climate condition. We used national marine environment monitoring data collected by National Fisheries Research & Development Institute(NFRDI) from 2000-2009. For the reference values, we used maximum seasonal mean from 2000 to 2007 for DIN, DIP, and chlorophyll-a and minimum seasonal mean for secchi depth measured at stations without the influence of river runoff in each ecological regions. For the reference value of bottom dissolved oxygen saturation, we used minimum mean value of 90% calculated from minimal riverine influence stations of whole regions. We calculated enrichment score for each assessment criteria. The enrichment score of DIN, DIP, and Chlorophyll-a was 1 (=< reference value), 2 (< 110% of reference value), 3 (< 125% of reference value), 4 (< 150% of reference value), and 5 (> 150% of reference value). The enrichment score of DO saturation and Secchi depth was 1 (> reference value), 2 (> 90% of reference value), 3 (>75 % of reference value), 4 (> 50% of reference value), and 5 (< 50% of reference value). We calculated water quality index using weighted linear combination of five enrichment score for the comparison of whole regions. From the water quality index distribution calculated from all stations between 2000 and 2007 period, we classified into 5 grade based on the standard deviation calculated from total water quality index. We assigned grade very good(I), good(II), moderate(III), bad(IV), and very bad(V) when the water quality index was less than 23, minimum + 1 sd, +2 sd, +3 sd, and grater than minium+ 3 sd, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.3
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• pp.150-156
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• 2005

The increasing emission of greenhouse gases may change agricultural environment. The agronomic productivity will depend upon change of temperature, precipitation, solar radiation and fertilization. This study was conducted to investigate greenhouse gas emission with irrigation water depth in paddy field. Area of each experiment plot is $70m^2$, Three treatments with three replications were carried out in this experiment, which was laid out as randomized complete block design. The treatments of irrigation water were maximum field water capacity and 4 and 8 cm depth. The application rate of fresh rice straw was $8,000kg\;ha^{-1}$ in combination with chemical fertilizers ($110kg\;N\;ha^{-1}$, $45kg\;P_2O_5\;ha^{-1}$ and $57kg\;K_2O\;ha^{-1}$). The $CH_4$ emission was highest at 32 days after rice transplanting with rice straw treatment. The $CH_4$ emission in the plot of maximum field water capacity was lower compared with 4 and 8 cm of irrigation depth. $CH_4$ and $N_2O$ emission under different water depth in the paddy field were 30 and $1.52kg\;ha^{-1}$ at 8 cm depth, 281 and $1.71kg\;ha^{-1}$ at 4 cm depth, and 219 and $2.01kg\;ha^{-1}$ at water saturated condition. The total emission of greenhouse gases equivalent to $CO_2$ emission with rice straw application were $6,939kg\;CO_2\;ha^{-1}$ at 8 cm depth plot, $6,431kg\;CO_2\;ha^{-1}$ at 4 cm depth plot and $5,222kg\;CO_2\;ha^{-1}$ at water saturated condition. The GWPs without rice straw application were $4,449kg\;CO_2\;ha^{-1}$ at 8 cm depth plot, $3,702kg\;CO_2\;ha^{-1}$ at 4 cm depth plot and $4,579kg\;CO_2\;ha^{-1}$ at water saturated condition.

• Tuberculosis and Respiratory Diseases
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• v.46 no.6
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• pp.836-845
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• 1999

Background : Obesity is present in the majority of adult patients with obstructive sleep apnea(OSA) and is considered to be a major risk factor for its development. A reduction in body weight has been associated with substantial improvement in the severity of apnea. However, a variety of treatment strategies for obesity have yielded limited sucess. This study was done to determine resting energy expenditure(REE) in patients with obstructive sleep apnea and the correlation between the severity of sleep apnea and REE, and to investigate whether leptin influences REE and correlated with the severity of sleep apnea in 39 patients with OSA and 45 controls matched for obesity. Method : Overnight polysomnography was performed on all subjects using standard techniques. Measurements of REE were made using a Sensormedic Vmax 229 and a canopy system. Serum leptin concentration was measured by human leptin RIA kit of LINCO Research INC. Results : REE was greater in patients with OSA compared with controls, but there was no difference between the two groups on REE%. And also there was no significant correlation between anthropometric data, polysomnographic data and REE%. Serum leptin was linearly related to body mass index(BMI), apnea index, apnea hypopnea index and lowest arterial oxygen saturation($SaO_2$) but not related to REE%. Conclusion : This study suggests the followings. Firstly patients patients with sleep apnea have a pattern of obesity characterized by energy homeostasis at an elevated body weight set-point. In order to achieve a lower body weight in these patients, it may be necessary to increase energy expenditure by increasing physical activity. Secondly leptin level was not correlated with REE, suggesting that leptin may predominantly regulate body fat by altering eating behavior rather than calorigenesis. Lastly leptin level was significantly correlated with the severity of sleep apnea. These elevated level of leptin in patients of sleep apnea may be related to the obesity, however it needs further studies to determine the relationship between the severity of sleep apnea and serum leptin.

• The Journal of Engineering Geology
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• v.14 no.2
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• pp.199-210
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• 2004

In this study, the physical and mechanical properties of the weathered shale soils distributed in the Hwasun area have been measured in the laboratory. The physical and mechanical properties of the weathered shale soils in the study area as follows: the specific gravity is 2.66 to 2.68, the liquid limit is 36.39 to 36.92(%), the plastic limit is 18.53 to 19.48(%), the plasticity index is 17.44 to 17.86 and soil classification is CL. The maximum dry unit weight and optimum moisture content as calculated by compaction test is 22.5 to 23% and 1.58 to $1.61t/\textrm{m}^3$, respectively. The result of direct shear testing show that cohesion in saturated and unsaturated conditions increases according to the increase of dry unit weight. Internal friction angle in an unsaturated condition increases with an increase of dry unit weight, but in a saturated condition, it increases after decreasing. When compares with engineering characteristics of tile weathered shale soils in the Daegu area (Kim et al., 1995), specific gravity is found to be similar, but the liquid and plastic limit of soil samples in this study area is slightly higher than those of soil samples in the Daegu area.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.5
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• pp.23-30
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• 2000

To compensate the nonlinearity of electroabsorption modulator(EAM) resulting from its near exponential transfer function, a semiconductor optical amplifier(SOA) that has a log transfer function is used. Since the transfer function of SOA is inverse to that of EAM, the intermodulation distortion(IMD) of EAM can be reduced by cascading SOA to EAM. Also, the RF gain can be increased by the optical gain of SOA. For these reasons, spurious free dynamic range(SFDR) of EAM is enhanced by connecting SOA to EAM in series and operating in gain salutation region. To improve the nonlinearity compensation of EAM, the increased gain of SOA is required and the slope of gain saturation, the ratio of gain to input SOA power, needs to be steep. However, signal spontaneous beat noise that is the dominant system noise increases in proportion to the gain such that the SFDR of EAM is reduced. The higher the gain of SOA is, the more ASE is increased. Thus the noise level of system is increased and the following SFDR of EAM is decreased. The slope of gain saturation region and ASE of have trade-off relation and the optimization is achieved at 8㏈ optical gain. 9㏈ enhancement of SFDR of EAM is obtained. This scheme is easy to embody the linear EAM and the integration with three components (DFB-LD, EAM and SOA) offers many merits, such as low insertion loss, low chirping and low polarization sensitivity.