• Geomechanics and Engineering
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• v.36 no.3
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• pp.217-229
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• 2024

Determining lateral earth pressure coefficient (EPC) K is a classic problem in geotechnical engineering. It is a key parameter for estimating the stresses in backfilled openings. For backfilled openings with rigid and immobile walls, some suggested using the Jaky's at-rest earth pressure coefficient K₀ while other suggested taking the Rankine's active earth pressure coefficient K_a. A single value was proposed for the entire backfilled opening. To better understand the distributions of stresses and K in a backfilled opening, a series of laboratory tests have been conducted. The horizontal and vertical normal stresses at the center and near the wall of the opening were measured. The values of K at the center and near the wall were then calculated with the measured horizontal and vertical normal stresses. The results show that the values of K are close to K_a at the center and close to K₀ near the wall. Furthermore, the experimental results show that the horizontal stress is almost the same at the center and near the wall, indicating a uniform distribution from the center to the wall. It can be estimated by analytical solutions using either K_a or K₀. The vertical stress is higher near the center than near the wall. Its analytical estimation can only be done by using K_a at the center and K₀ near the wall. Finally, the test results were used to calibrate a numerical model of FLAC2D, which was then used to analyze the influence of column size on the stresses and K in the backfilled opening.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.53-60
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• 2002

Motion of lung tumors from respiration has been reported in the literature to be as large as of 1-2 cm. This motion requires an additional margin between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV). While such a margin is necessary, it may not be sufficient to ensure proper delivery of Intensity Modulated Radiotherapy (IMRT) to the CTV during the simultaneous movement of the DMLC. Gated treatment has been proposed to improve normal tissues sparing as well as to ensure accurate dose coverage of the tumor volume. The following questions have not been addressed in the literature: a) what is the dose error to a target volume without gated IMRT treatment\ulcorner b) what is an acceptable gating window for such treatment. In this study, we address these questions by proposing a novel technique for calculating the 3D dose error that would result if a lung IMRT plan were delivered without gating. The method is also generalized for gated treatment with an arbitrary triggering window. IMRT plans for three patients with lung tumor were studied. The treatment plans were generated with HELIOS for delivery with 6 MV on a CL2100 Varian linear accelerator with a 26 pair MLC. A CTV to PTV margin of 1 cm was used. An IMRT planning system searches for an optimized fluence map ${\Phi}$ (x,y) for each port, which is then converted into a dynamic MLC file (DMLC). The DMLC file contains information about MLC subfield shapes and the fractional Monitor Units (MUs) to be delivered for each subfield. With a lung tumor, a CTV that executes a quasi periodic motion z(t) does not receive ${\Phi}$ (x,y), but rather an Effective Incident Fluence EIF(x,y). We numerically evaluate the EIF(x,y) from a given DMLC file by a coordinate transformation to the Target's Eye View (TEV). In the TEV coordinate system, the CTV itself is stationary, and the MLC is seen to execute a motion -z(t) that is superimposed on the DMLC motion. The resulting EIF(x,y)is inputted back into the dose calculation engine to estimate the 3D dose to a moving CTV. In this study, we model respiratory motion as a sinusoidal function with an amplitude of 10 mm in the superior-inferior direction, a period of 5 seconds, and an initial phase of zero.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.1025-1031
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• 1999

Alloys of TiAl with six different compositions. i. e., Ti-(42, 44)Al-2Nb-4V. Ti-(42, 44)Al-4Nb-2V and Ti -(42, 44)Al-4Nb-2Cr, were manufactured by arc-melting. and their oxidation behavior was studied. Both isothermal and cyclic oxidation tests were performed at 700, 800 and $900^{\circ}C$ in air for 50hr. The oxidation resistance increased in the order of Ti-(42, 44)Al-2Nb-4V, Ti-(42, 44)Al-4Nb-ZV and Ti-(42, 44)Al-4Nb-2Cr. It was found that V was a deleterious element, while Cr was a beneficial element in terms of oxidation resistance. During oxidation, a simultaneous interdiffusion was observed. All the constituent elements in the base alloys diffused outward. whereas oxygen from the atmosphere diffused inward, to form triple oxide layers composed of an outermost $\textrm{TiO}_2$ layer. upper ($\textrm{TiO}_2+\textrm{Al}_2\textrm{O}_3$) mixed layer, and lower $\textrm{TiO}_2$-rich layer.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.155-162
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• 2020

Acetyl xylan esterase (AXE; E.C. 3.1.1.72) is one of the accessory enzymes for xylan degradation, which can remove the terminal acetate residues from xylan polymers. In this study, two genes encoding putative AXEs (LaAXE and BhAXE) were cloned from Lactobacillus antri DSM 16041 and Bacillus halodurans C-125, and constitutively expressed in Escherichia coli. They possess considerable activities towards various substrates such as p-nitrophenyl acetate, 4-methylumbelliferyl acetate, glucose pentaacetate, and 7-amino cephalosporanic acid. LaAXE and BhAXE showed the highest activities at pH 7.0 and 8.0 at 50℃, respectively. These enzymes are AXE members of carbohydrate esterase (CE) family 7 with the cephalosporine-C deacetylase activity for the production of antibiotics precursors. The simultaneous treatment of LaAXE with Thermotoga neapolitana β-xylanase showed 1.44-fold higher synergistic degradation of beechwood xylan than the single treatment of xylanase, whereas BhAXE showed no significant synergism. It was suggested that LaAXE can deacetylate beechwood xylan and enhance the successive accessibility of xylanase towards the resulting substrates. The novel LaAXE originated from a lactic acid bacterium will be utilized for the enzymatic production of D-xylose and xylooligosaccharides.

• Journal of Korean Neurosurgical Society
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• v.40 no.5
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• pp.323-329
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• 2006

Objective : This study was designed to analyze surgical strategies for patients with intractable supplementary sensorimotor area[SSMA] seizures. Methods : Seventeen patients who had surgical treatment were reviewed retrospectively. Preoperatively, phase I [non-invasive] and phase II [invasive] evaluation methods for epilepsy surgery were done. Seizure outcome was assessed with Engel's classification. The mean follow-up period was 27.2 months [from 12 months to 54 months]. Results : An MRI identified structural abnormality in eight patients and 3D-surface rendering revealed abnormal gyration in three. PET, SPECT, and surface EEG could not delineate the epileptogenic zone. Video-EEG monitoring with a subdural grid or depth electrodes verified the epileptogenic zone in all patients. Surgical procedures consisted of a resection of the SSMA and simultaneous callosotomy in two patients, a resection of the SSMA extending to the adjacent area in seven, a resection of a different area without a SSMA resection in seven, and a callosotomy in one. Seizure outcomes were class I in 11 [65%]. class II in five [29%], class III in one [6%]. Conclusion : In patients with intractable SSMA seizure, surgery was an excellent treatment modality. Precise delineation of the epileptogenic zone based on multimodal diagnostic methods can provide good surgical outcomes without neurological complications.

• The Korean Journal of Physiology
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• v.9 no.1
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• pp.1-11
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• 1975

The present experiments were carried out to investigate the active center of sodium and potassium ion activated adenosine triphosphatase. An ATPase, activated by sodium ion Plus potassium ion in the presence of magnesium ion, and inhibited by ouabain, has been obtained from rabbit red cell ghosts. The ATPase activity was measured by inorganie phosphate released from ATP. From this values of the measured inorganic phosphate, the activity of ATPase was calculated. The following results were observed. 1. The activity of $(Na^++K^+)-ATPase$ is inhibited by ouabain. This effect may not be due to an effect on sulfhydryl groups, amino groups, carboxyl groups, imidazole groups and hydroxyl groups. 2. The $(Na^++K^+)$-activated enzyme system is inhibited by p-chloromercuribenzoate and by d nitroflurobenzene, and this effect may be due to an effect on sulfhydryl groups. These results indicate that the sulfhydryl groups is attached to sodium-potassium dependent adenosine triphosphate, an aspect of the pump. 3. The $(Na^++K^+)-activated$ enzyme system is inhibited by maleic anhydride and this inhibition is reversed by lysine. This Seems to indicate that the active center of this enzyme is the amino groups. 4. The $(Na^++K^+)$-activated enzyme system is inhibited by iodoacetamide and this inhibition is reversed by the simultaneous present of cysteine and aspartic acid in the suspension medium. This result indicates that this enzyme contains sulfhydryl groups and carboxyl groups. 5. The $(Na^++K^+)-ATPase$ activity is accelerated by adrenaline and this effect is abolished by aspartic acid. This effect of aspartic acid indicate that carboxyl group might be involved in the hydrolysis of ATP by the enzyme system. On the hydrolysis of ATP by the enzyme system. On the basis of these experiments it f·as suggested that the active center of $(Na^++K^+)-activated$ ATPase contains sulfhydryl groups, amino groups and carboxyl groups.

• Journal of the Korean Home Economics Association
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• v.46 no.4
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• pp.47-59
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• 2008

With increasing numbers of immigrant workers in Korea, the supply of socially and culturally acceptable housing has become an important issue. The purpose of this study was to analyze the state of Goryo-in housing and domestic living conditions in metropolitan areas of Korea. This study will present essential information directly relevant to the establishment of practical housing policy for Goryo-in in Korea. Furthermore, data collected and analyzed here will enable comparative investigation with Goryo-ins who live in Russia and Central Asia. Using ethnographic methodologies, we examined 20 Goryo-in households in relation to their usage of domestic space. The following conclusion were established; 1). The most popular L D K(Living Dining Kitchen)type consisted of kitchen plus one or two bedrooms. The majority of households lived in quarters with separated kitchen and living room areas. 2). Most households had a washing machine in the bathroom due to a lack of space, and they regarded the bathtub and the drain hole of the bathroom as very necessary. The Goryo-ins interviewed preferred quarters with separate bathroom and toilet areas, in order to allow simultaneous use. 3). Their most preferred seating style was chairs, while making Kimchi at home was not very popular. 4). All respondents took their shoes off and wore slippers at home, while also indicating a preference for designated shoes space at the entrance to the house. 5) Half of the households had a carpet or mat in the bedroom or living room, both for keeping warm and aesthetic reasons. 6). All households had modified Ondol heating system and demonstrated satisfaction with this. The majority of Goryo-ins interviewed had a different living style compared to households in Russia and Central Asia which were related to less favorable economic conditions in Korea.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.17 no.4
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• pp.470-477
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• 2010

Purpose: The purpose of this study was to explore the levels of depression and predictors of depression in middle-school girls. Method: A self-report survey was conducted with 2nd and 3rd grade students in a girls'middle school (N=401) in Pusan. Data were analyzed with descriptive statistics, Pearson correlation, and simultaneous multiple regression using the SPSS program. Results: The mean score for the Center for Epidemiologic Studies-Depression Scale (CES-D) was 20.63. The level of depression was negatively related to problem-solving ability, self-esteem, total household income, school achievement, self-perception of body-image, and satisfaction in relationships with siblings, parents, and friends. A multivariate approach showed that predictors explained 61% of variance in depression. Significant predictors of depression were self-esteem (${\beta}$=-.38), problem-solving ability (${\beta}$=-.34), and satisfaction in relationships with friends (${\beta}$=-.14) and parents (${\beta}$=-.08). Conclusion: The findings suggest that it is important to develop educational programs to increase self-esteem and problem-solving abilities in middle school girls. Considering the high levels of depression in middle school girls, school nurses play an important role in detecting and reducing emotional tension among these students. Nursing interventions, including art therapy, problem-solving counseling, and bibliotherapy could be useful in enhancing self-esteem, problem-solving abilities, and satisfaction in relationship with friends, siblings and parents.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.529-532
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• 2003

Quench behavior of resistive superconducting fault current limiters (SFCLs) with various pattern shapes was investigated. The pattern shapes employed were meander, bi-spiral, and spiral shapes of identical line width, gap and margin. SFCLs were fabricated from YBCO thin films grown on two-inch diameter $Al_2O_3$ substrates under the same conditions. Resistance rise of current limiting elements was low at a spiral shape before the whole quench completion, which may act as a disadvantage for simultaneous quench in serial connection between current limiting elements, but the temperature tended to have similar values at higher voltages. On the other hand, bi-spiral shape was severe at insulation level between current limiting lines. When these aspects were considered, we concluded that a meander shape was appropriate to design for a resistive SFCL based on thin films except the concentration of electric field at edge areas of strip lines.

• Animal cells and systems
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• v.8 no.4
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• pp.295-300
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• 2004

In the breeding colony of black-tailed gull, as nests of conspecific neighbors are very closely located, chicks are permanently exposed by sound and visual stimuli produced by adult conspecifics approaching their nests. The chicks, therefore, may need to learn ways to appropriately respond to their parents approach. In this study we experimentally manipulated sensory stimulation that is potentially provided by the parents to the offspring. Chicks incubated in the laboratory were exposed to a mew call of the conspecific adult. Then they were tested in three situations differing in sensory stimulation: 1) visual stimulation only, 2) auditory stimulation only, and 3) Simultaneous visual and auditory stimulations. We observed occurrence of different response of the chicks, which were categorized into three behaviors (begging call response, chirirah call and pecking behavior). We also investigated intensity of the chicks call in response to the different stimulations and the degree of response with age. The chicks exposed to only auditory stimulation made significantly more chirirah calls. The intensities (dB) of the mew call and chicks chirirah call were directly correlated. On the other hand, when chicks just saw the stuffed adult gull, they responded significantly more with a begging call and pecking behavior. In the situation of costimulation, the chicks responded with a begging call and pecking, but less frequently than visual stimulation only. The results suggest that young black-tailed gulls use call repertories to properly respond to parents behavior. Such results suggest an evolutionary process for uncreasing their survival rate in a group breeding site.