• Korean Journal of Soil Science and Fertilizer
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• v.38 no.6
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• pp.301-306
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• 2005

Asian dust was collected in Korea and soils in the arid area of northern China were analysed for its physical and chemical properties, and mineral compositions for in order to interpret the origin of Aeolian soils and estimate the effect of dust wind on the soil environment in Korea. Asian dust was collected at Suwon in Korea from 2002 to 2004. Soil samples were collected from the desert and Loess plateaus around Gobi desert in China. As a result of analysis of desert soil distributed on northern region and Loess soils in China, it was observed that soil pH was about 9, organic matter 11 to $23g\;kg^{-1}$, and CEC 7.1 to $18.4cmolc\;kg^{-1}$, showing a high spatial variation among different sampling locations. About 62 to 80% of particles were composed of quartz and feldspars, 2 to 14% calcite ($CaCO_3$) and dolomite [$Ca{\cdot}Mg(CO_3)_2$], and trace other clay minerals. All the dust particles in Korea were below 50 m in diameter, and the mineral compositions were quartz, mica, feldspar and some clay minerals. Major components of clay mineral of Asian dust was mainly illite as compared to the kaolin of soils in Korea. The base saturation of exchangeable Ca, Mg, K and Na in the Asian dust was above 250% due to the high content calcite. Most of upland soil in Suwon was thin and sharp type, but Asian dust in Korea was the spherical shape. Asian dusts in Suwon, Korea, did not show a definite mineralogical variation of the dust during the collection period. Difference between the Asian dust collected in Korea and the soils in arid area of China was observed in the physical and chemical properties, especially for particle size distribution, cations such as Ca, Mg, K and Na. However, some similarities were found on the mineral compositions and chemical properties between Asian dust collected in Korea and the loess of China.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.103-109
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• 2009

Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, and have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for classification of hydrologic soil group (HSG) of soils originated from limestone by measuring the infiltration rate of surface soils and percolation rate of sub soils. Soils used for the experiment were 6 soils in total : Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. Particle size distribution and organic matter content of the soils were analyzed. HSG, which was made by USDA NRCS(National Resources Conservation Service) for hydrology, of Gwarim series with O horizon of accumulated organic matter was classified as type A which show the properties of low runoff potential, rapid infiltration and percolation rate. HSG of Mosan series, which has high gravel content and very rapid permeability, was classified as type B/D because of the impermaeble base rock layer under 50cm from surface. HSG of Jangseong series with shallow soil depth was classified as type C/D owing to the impermaeble base rock layer under 50cm from surface. HSG of Maji series was type B, and HSG of Anmi series used as paddy land was type D because of slow infiltration and percolation rate caused by the disturbance of surface soil by puddling. HSG of Pyeongan series having a sudden change of layer in soil texture was type D because of the slow percolation rate caused a the layer.

• Journal of Korean Society of Transportation
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• v.29 no.5
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• pp.121-138
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• 2011

More affordable and available cutting-edge technologies (e.g., wireless vehicle communication) are regarded as a possible alternative to the fixed infrastructure-based traffic information system requiring the expensive infrastructure investments and mostly implemented in the uninterrupted freeway network with limited spatial system expansion. This paper develops an advanced decentralized traveler information System (ATIS) using vehicle-to-vehicle (V2V) communication system whose performance (drivers' travel time savings) are enhanced by three complementary functions (autonomous automatic incident detection algorithm, reliable sample size function, and driver behavior model) and evaluates it in the typical $6{\times}6$ urban grid network with non-recurrent traffic state (traffic incident) with the varying key parameters (traffic flow, communication radio range, and penetration ratio), employing the off-the-shelf microscopic simulation model (VISSIM) under the ideal vehicle communication environment. Simulation outputs indicate that as the three key parameters are increased more participating vehicles are involved for traffic data propagation in the less communication groups at the faster data dissemination speed. Also, participating vehicles saved their travel time by dynamically updating the up-to-date traffic states and searching for the new route. Focusing on the travel time difference of (instant) re-routing vehicles, lower traffic flow cases saved more time than higher traffic flow ones. This is because a relatively small number of vehicles in 300vph case re-route during the most system-efficient time period (the early time of the traffic incident) but more vehicles in 514vph case re-route during less system-efficient time period, even after the incident is resolved. Also, normally re-routings on the network-entering links saved more travel time than any other places inside the network except the case where the direct effect of traffic incident triggers vehicle re-routings during the effective incident time period and the location and direction of the incident link determines the spatial distribution of re-routing vehicles.

• Radiation Oncology Journal
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• v.15 no.4
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• pp.321-329
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• 1997

Purpose : It is well known that the risk of lymph nodes metastases to head and neck cancers are influenced by the location and size of the Primary tumor. as well as the degree and types of histological differentiation. However, data on the statistical analyses of lymph node metastases from the head and neck cancers among Korean Population are not available at present. In order to obtain current status of such data, we have analyzed cancer patients at the department of radiation oncology, korea universityhospital for radiation treatment. Materials and Methods : We have evaluated nine-hundred and ninetyseven (997) head and neck cancer Patients who visited to the Department of radiation oncology, between November 1981 to December 1995. After careful physical examinations and CAT scan, Patients were divided into two groups, those with positive lymph node metastases and with negative lymph node metastases. The nodal status were classified according to the TNM system of American Joint Committee on Cancer (AJCC) Besults : Four-hundred and sixteen Patients out of the 997 patients were lymph node positive $(42\%)$ and 581 patients were lymph node negative $(58\%)$ when they were first presented at the department of radiation oncelogy. According to the AJCC classification, the distribution of positive lymph node is as follow: Nl:106 $(25.5\%),\;N2a:100\;(24\%),\;N2b:68\;(16.4\%),\;N2c:69\;(16.6\%),\;3:73\;(15\%).$ respectively. The frequency of lymph node metastases according to the primary sites is as follow : larynx 283 $(28.5\%)$, paranasal sinuses: 182 $(18\%),\;oropharynx:144\;(14.5\%)\;nasopharynx:122(12\%),\;oral\;cavity\;92\;(9\%),\;hypopharynx:71\;(7\%),\;falivary\;gland:58\;(6\%)$ unknown primary:31 $(3\%),\;skin:\;14(2\%)$,. The most frequent Primary site for the positive Iymph node metastases was nasopharynx $(71\%)$ followed by hypopharynx $(69\%),\;oropharynx\;(64\%),\;oral\;cavity\;(39\%)$ The most common histologic type was squamous cell carcinoma (652/997: $65.4\%$). followed by malignant lymphoma $(109/997:11\%)$. Conclusion : Statistical results of lymph node metastases from head and neck cancer at our department were very similar to those obtained from other countries. It is concluded that the location of Primary cancer influences sites of metastases on head and neck, and stage of the primary cancer also influences the development of metastatic lesions. Since the present study is limited on the data collected from one institute. further statistical analyses on Korean cancer Patients are warrented.

• Radiation Oncology Journal
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• v.16 no.2
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• pp.185-194
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• 1998

Purpose : With the development of stereotactic immobilization systems capable of reliable serial repositioning, fractionated stereotactic radiation therapy (FSRT) offers the Potential for an improved treatment outcome by excellent dose delivery, and dose distribution characteristics with the favorable radiobiological properties of fractionated irradiation. We describe our initial experience using FSRT for the treatment of intracranial benign tumor. Materials and Methods : Between August 1995 and December 1996. 15 patients(7 males and 8 females aged 6-70 years) were treated with FSRT. The patients had the following diagnosis pituitary adenoma(10) including one patient who previously had received radiotherapy, craniopharyngioma (2), acoustic neurinoma (1), meningioma (2). Using the Gill-Thomas-Cosman relocatable head frame and multiple non-coplanar therapy, the daily dose of 2Gy was irradiated at 90% to 100% isodose surface of the isocenter The collimator sizes ranged from 26mm to 70mm. Results : In all patients except one follow-up lost, disease was well-controlled. Acute complication was negligible and no patient experienced cranial nerve neuropathies and radiation necrosis. In overall patient setup with scalp measurements, reproducibility was found to have mean of $1.1{\pm}0.6mm$ from the baseline reading. Conclusion : Relocatable stereotactic system for FSRT is highly reproducible and comfortable. Although the follow-up period was relatively short. FSRT is considered to be a safe and effective radiation technique as the treatment of intracranial tumor. But the fractionation schedule(fraction size, overall treatment time and total dose) still remains to be solved by further clinical trials.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.261-267
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• 1999

Purpose : In FSRT (Fractionated stereotactic radiotherapy) planning, we studied the usefulness between multiple arc FSRT and conformal FSRT by comparing tumor shape and DVH (dose volume histogram). Materials and Methods In Chungnam Univ. hospital, we had treated the sixteen patients with FSRT from Aug. 1997 to Dec. 1998. In choosing multiple arc FSRT or conformal FSRT, we had considered If (irregular factor) after calculating tumor volume and surface area. We had considered multiple arc FSRT if tumor shape was similar to sphere or the value of If was less than 1.25, conformal FSRT if tumor shape was very irregular or If was more than 1.3. For evaluation of treatment planning, we had considered the appropriate DVH for tumor volume and for critical organs. Results : The errors between reference point and the coordinates point on AP, Lat radiography were less than 1 mm before treatment. We had planned $3\~$5 arcs for multiple arc FSRT, $5\~6$ports for conformal FSRT. The mean dose distribution of tumor volume of cumulative DVH between multiple arc FSRT and conformal FSRT was 90.6, 85%, respectively. The dose of critical organs irradiated was less than $5\%$ maximum dose of cumulative DVH. Conclusion : We had obtained the similar value between multiple arc FSRT and conformal FSRT, so that we had appropriate treatment planning of FSRT for multiple arc FSRT and conformal FSRT according to tumor shape and size.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.117-126
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• 1999

Hampyong Bay is a semienclosed and macrotidal bay which opens to the eastern Yellow Sea through a narrow inlet in the southwestern coast of Korea. In order to understand the tidal-flat sedimentation in the semienclosed setting, morphology, sediments, accumulation rate and sea cliff erosion were investigated in the tidal flat of Hampyong Bay. The tidal flat of Hampyong Bay lacks intertidal drainage systems, and generally shows the concave-upward profile whose relief is designated by marked morphological features such as high-tide beaches, intertidal sand shoals and tidal creeks. Surfacial sediments of the tidal flat mainly consist of mud, sandy mud, gravelly mud, gravelly sand and muddy gravel, thus showing the textural characteristics of multimodal grain-size distribution, poorly sorting and positive skewness. The sediments generally coarsen landward due to the increase in coarse fraction content. Sedimentary structures are deeply bioturbated, but parallel lamination and lenticular bedding are locally found in the mudflat near mean low water line. Annual accumulation rates across the tidal flat (along Line SM) average -5.2 cm/yr with a range of -45.8~+4.2 cm/yr, indicating that the tidal flat is erosional. In general, erosion rates of upper and lower tidal flat are higher than those of middle tidal flat. Seasonally, the erosion rates are much higher during spring and winter when dominant wind direction corresponds to the long axis of Hampyong Bay. Sea cliffs are eroded at a rate of 1.4 m/yr. The biggest sea cliff erosion generally occurs 1~2 months later after tidal flats were extensively eroded. Such erosions of tidal Oats and sea cliffs in the semienclosed bay setting are interpreted to be due to wind waves coupled with local sea-level rise.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.207-216
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• 2009

Three distinct types of fluid inclusions in amethyst and quartz crystals are associated with metamorphic events in the Korea Amethyst deposit from Uljin-Gun, Gyeongbuk Province. The amethyst displays bimodal grain size distribution in fine-grained, strain-free equigranular quartz with coarse-grained quartz grains with kink bands and undulose extinction. Type I inclusions are liquid-rich and salinity is 0~7 wt% NaCl and the homogenization temperatures ($T_h$) $91{\sim}231^{\circ}C$ with eutectic temperatures ($T_e$) $-52{\sim}-20^{\circ}C$. Type II inclusions are vapor-rich (80~90 vol%). The salinity and $T_h$ ranges 3~6 wt% NaCl and $230{\sim}278^{\circ}C$, respectively with $T_e$ $-56{\sim}-23^{\circ}C$. Type III inclusions contain a daughter mineral other than NaCl. The salinity ranges 32~36 wt% NaCl and $T_h$ $210{\sim}271^{\circ}C$. The textural and fluid inclusion evidences suggest that the host Buncheon granite gneiss and Amethyst pegmatite experienced dynamic recrystallization and the studied fluid inclusions are metamorphic in origin. The metamorphic event possibly occurred at higher temperature than $271{\sim}278^{\circ}C$. The amethysts from Uljin Korea Amethyst can be distinguished from the synthetic amethyst on basis of the distinctive two and three-phases fluid inclusions. Furthermore, it is noticeable that Korea amethyst do not contain NaCl-bearing and $CO_2$-rich fluid inclusions unlike those compared to those from Eonyang and Samcheonpo deposits related to unmetamorphosed granitic rocks.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.700-708
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• 1996

Electroless plating technique was utilized to flip chip bonding to improve surface mount characteristics. Each step of plating procedure was studied in terms pf pH, plating temperature and plating time. Al patterned 4 inch Si wafers were used as substrstes and zincate was used as an activation solution. Heat treatment was carried out for all the specimens in the temperature range from room temperature to $400^{\circ}C$ for $30^{\circ}C$ minutes in a vacuum furnace. Homogeneous distribution of Zn particles of size was obtained by the zincate treatment with pH 13 ~ 13.5, solution concentration of 15 ~ 25% at room temperature. The plating rates for both Ni-P and Au electroless plating steps increased with increasing the plating temperature and pH. The main crystallization planes of the plated Au were found to be (111) a pH 7 and (200) and (111) at pH 9 independent of the annealing temperature.

• Applied Biological Chemistry
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• v.37 no.2
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• pp.130-141
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• 1994

A continuous two-stage membrane (1st-SCMR, MWCO 10,000; 2nd-SCMR, MWCO 5,000) reactor was developed and optimized for the production of fish skin gelatin hydrolysate with different molecular size distribution profiles using trypsin and pronase E. The optimum operating conditions in the 1st-step membrane reactor using trypsin were: temperature, $55^{\circ}C$ ; pH 9.0; enzyme concentration, 0.1 mg/ml; flux, 6.14 ml/min; reaction volume, 600 ml; and the ratio of substrate to trypsin, 100 (w/w). After operating for 1 hr under the above conditions, 79% of total amount of initial gelatin was hydrolysed. In the 2nd-step using pronase E under optimum operating conditions[temperature, $50^{\circ}C$ ; pH 8.0; enzyme concentration, 0.3 mg/ml; flux, 6.14 ml/min; reaction volume, 600 ml; and the ratio of substrate to pronase E, 33 (w/w)], the 1st-step hydrolysate was hydrolysed above 80%. Total enzyme leakages in the 1st-step and 2nd-step membrane reactors were about 11.5% at $55^{\circ}C$ for 5hrs and 9.0% at $50^{\circ}C$ for 4 hrs, respectively. However, there was no apparent correlation between enzyme leakage and substrate hydrolysis. The membrane has a significant effect on activity lose of trypsin and pronase E activity for 1 hr of the membrane reactors operation. The loss of initial activity of enzymes were 34% and 18% in the 1st-step and 2nd-step membrane reactor, whereas were 23% and 10% after operating time 3 hr in the 1st-step and 2nd-step membrane reactor lacking the membrane, respectively. The productivities of 1st-step and 2nd-step membrane reactor for 8 times of volume replacement were 334 mg and 250 mg per mg enzyme, respectively.