• Journal of the Korean Geosynthetics Society
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• v.10 no.2
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• pp.73-79
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• 2011

Based on the results of Part 1 of our two-parts paper, the possibility on field applicability of CMDS(Coal Mine Drainage Sludge) mixed with bentonite and cement as a liner in landfill sites was investigated. The optimum moisture content that met the landfill liner condition was obtained when the ratio of CMDS: bentonite: cement was 1: 0.5: 0.3 in a lab-scale. The relative compaction was measured in 90.1%, which results for construction field have been generally acceptable. In this study, a large-scale Lysimeter($1.0m{\times}1.5m{\times}2.0m$) was used to simulate the effects of the layer on the freeze/thaw by -20 average temperature. The mixture after freezing/thawing showed compressive strength more than $5kg/cm^2$, which was satisfied with EPA standards. Initial permeability of CMDS was $7.10{\times}10^{-7}cm/s$ and permeability its mixture after freezing/thawing was increased to $9.80{\times}10^{-7}cm/s$. The change of temperature in the layers rises and falls with linear and temperature gradient keep maintain the present state. Moisture contents in the layers have not been radically changed. Through the leaching test determined by KSLT method, it was found that heavy metals excluding Zn and Ni were not leached out or leached out less than the standards during 7 cycles of freezing/thawing process. Since it shows the increased permeability about 1.5 times and slight change in moisture content, but it was satisfied with EPA standar through 7 cycles of freezing/thawing process, this mixture can be applied as a liner in landfill final cover system.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.811-817
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• 2006

The primary purpose of this study is to estimate the guaranteed strength and construction quality of the combined high flowing concrete which is used in the slurry wall of underground LNG storage tank. The required compressive strength of this type of concrete become generally known as a non economical value because it is applied the high addition factor for variation coefficients and low reduction factor under water concrete. Therefore, after estimation of the construction quality and guaranteed strength in actual site work, this study is to propose a suitable equation to calculate the required compressive strength in order to improve its difference. Application results in actual site work are shown as followings. The optimum nix design proportion is selected that has water-cement ratio 51%, sand-aggregate ratio 48.8%, and replacement ratio 42.6% of lime stone powder by cement weight. Test results of slump flow as construction quality give average 616~634mm. 500mm flowing time and air content are satisfied with specifications in the rage of 6.3 seconds and 4.0% respectively. Results of strength test by standard curing mold show that average compressive strength is 49.9MPa, standard deviation and variation coefficients are low as 1.66MPa and 3.36%. Also test results by cored cylinder show that average compressive strength is 66.4MPa, standard deviation and variation coefficients are low as 3.64MPa and 5.48%. The guaranteed strength ratio between standard curing mold and cored cylinder show 1.23 and 1.32 in the flanks. It is shown that applied addition factor for variation coefficients and reduction factor under water concrete to calculate the required compressive strength is proved very conservative. Therefore, based on these results, it is proposed new equation having variation coefficients 7%, addition factor 1.13 and reduction factor 0.98 under water connote.

• Journal of Aquaculture
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• v.20 no.2
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• pp.96-105
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• 2007

A pair of maroon clownfishes with an indonesian native, reared in recirculation culture system to develope its aquaculture techniques. Courtship, spawning behavior, egg developments and rearing of the maroon clownfish larvae were documented. The larval development were described with illustrative figures. The spawning was occurred 8 times between Feburary and August 2004. The gravid female spawned during 15:00-20:00. The male mainly took care of the eggs supplying oxygen by water currents using their pectoral fins, anal fin and mouth. The fertilized eggs were separative-adhesive and oval in shape, and $1.99{\pm}0.03\;mm$ in longer diameter and $0.88{\pm}0.03\;mm$ in shorter diameter. The fertilized eggs were in deep-orange color. Cleavage occurred in 30 minutes after fertilization, and the egg reached 2 cells stage in 1 hour 10 minutes after fertilization at $27.0^{\circ}{\pm}0.5^{\circ}C$. The embryo was formed in 23 hours 40 minutes after fertilization. Hatching began in between $120{\pm}2$ hours and $150{\pm}12$ hours after fertilization at $27.0^{\circ}C$ in the incubator. Total length (TL) of the newly hatched larvae was 3.22 mm with mouth and anus opened. Ten days after hatching, mean TL of the larvae were 6.21 mm with 28 dorsal fin rays, 17 anal fin rays and 28 caudal fin rays. Nineteen days after hatching, mean TL of the larvae were 9.34 mm. At this stage the larva had three white bands on the body, and they began to feed on commercial diet.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.61-69
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• 2009

Statement of problem: Porcelain veneers have become a popular treatment modality for aesthetic anterior prosthesis. Fitting porcelain veneers in the mouth usually involve a try-in appointment, which frequently results in salivary contamination of fitting surfaces. Purpose: An in vitro study was carried out to investigate the effect of silane treatment timing and saliva contamination on the resin bond strength to porcelain veneer surface. Material and methods: Cylindrical test specimens (n=360) and rectangular test specimens (n=5) were prepared for shear bond test and contact angle analysis. Whole cylindrical specimens divided into 20 groups, each of which received a different surface treatment and/or storage condition. The composite resin cement stubs were light-polymerized onto porcelain adherends. The shear bond strengths of cemented stubs were measured after dry storage and thermocycling (3,000 cycles) between 5 and $55^{\circ}C$. The silane and their reactions were chemically monitored by using Fourier Transform Infrared Spectroscopy analysis (FTIR) and contact angle analysis. One-way analysis of variance (ANOVA) and Dunnett's multiple comparison were used to analyze the data. Results: FT-IR analysis showed that salivary contamination and silane treatment timing did not affect the surface interactions of silane. Observed water contact angles were lower on the saliva contaminated porcelain surface and the addition of 37% phosphoric acid for 20 seconds on saliva contaminated porcelain increased the degree of contact angle. Silane applied to the porcelain, a few days before cementation, resulted in increasing the bond strength after thermocycling. Conclusion: Within the limitation of this study, it can be concluded that it would be better to protect porcelain prosthesis before saliva contamination with silane treatment and to clean the contaminated surface by use of phosphoric acid.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.21-30
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• 1985

The tension leg platform (TLP) is a kind of compliant structures, and is also a type of moored stable platform with a buoyancy exceeding the weight because of having tensioned vertical anchor cables. In this paper, among the various kinds of tension leg structures, Deep Oil Technology (DOT) TLP was analyzed because it has large-displacement portions of the immersed surface such as vertical corner pontoons and small-diameter elongated members such as cross-bracing. It also has results of hydraulic model tests, comparable with theorectical analysis. Because of the vertical axes of symmetry in the three vertical buoyant legs and because there are no larger horizontal buoyant members between these three vertical members, it was decided to develop a numerical algorithm which would predict the dynamic response of the DOT TLP using the previously developed numerical algorithm Floating Vessel Response Simulation (FVRS) for vertically axisymmetric bodies of revolution. In addition, a linearized hydroelastic Morison equation subroutine would be developed to account for the hydrodynamic pressure forces on the small member cross bracing. Interaction between the large buoyant members or small member cross bracings is considered to be negligible and is not included in the analysis. The dynamic response of the DOT TLP in the surge mode is compared with the results of the TLP algorithm for various combinations of diffraction and Morison forces and moments. The results which include the Morison equation are better than the results for diffraction only. This is because the vertically axisymmetric buoyant members are only marginally large enough to consider diffractions effects. The prototype TLP results are expected to be more inertially dominated.

• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.44-49
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• 2009

Purpose : Early surfactant treatment and minimal ventilation, bronchopulmonary dysplasia needed prolonged oxygen supplement is a problem. This study aimed to report the effects of early surfactant treatment and minimal ventilation on the prevention of bronchopulmonary dysplasia in respiratory distress syndrome. Methods : We retrospectively studied 139 premature newborn infants (gestational age, 36 weeks; birth weight, 1,500 gm) admitted to the neonatal intensive care unit of Daegu Fatima Hospital between January 2001 and December 2006. We analyzed the occurrence of bronchopulmonary dysplasia with respect to ventilator care and surfactant treatment. Results : The incidence of bronchopulmonary dysplasia was significantly higher with prolonged ventilator care, moderate to severe respiratory distress syndrome, and low Apgar score (P<0.001). Despite early surfactant treatment and minimal ventilation, mild bronchopulmonary dysplasia occurs in a considerable number of patients with mild respiratory distress syndrome. The patient group with low Apgar scores required ventilator care for a prolonged period (P=0.020). Conclusion : Early surfactant treatment and minimal ventilation shortens the duration of ventilator care; however, the preventive effects on bronchopulmonary dysplasia are limited. Therefore, not only early surfactant treatment and minimal ventilation but also appropriate management in the delivery room is essential.

• Journal of Life Science
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• v.19 no.9
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• pp.1226-1231
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• 2009

Enzyme substitution with recombinant phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) is currently being explored for treatment of phenylketonuria (PKU), an autosomal recessive genetic disorder with mutations of the gene encoding phenylalanine-4-hydroxylase (EC 1.14.16.1). However, oral administration of PAL is limited because of proteolytic digestion in the gastrointestinal tract. The aim of this study was to determine the biochemical properties of PAL and delinate the susceptibility of wild-type PAL to pancreatic proteolysis by exploring several mutants, and to develop therapeutic drugs with PAL for PKU. The specific activity of PAL was assayed and its optimal pH, temperature stability, and intestinal protease susceptibility were investigated. Its $V_{max}$ values for phenylalanine and tyrosine were 1.77 and $0.47{\mu}mol$/ min/mg protein, respectively, and its $K_m$ values were $4.77{\times}10^{-4}$ and $4.37{\times}10^{-4}\;M$, respectively. PAL showed an optimal pH at 8.5, corresponding to the average pH range of the small intestine. It showed no loss of activity at $-80^{\circ}C$ for 5 months and possessed 93.4% of its activity under $4^{\circ}C$ for 4 wks. PAL was susceptible to chymotrypsin digestion and, to a lesser extent, to trypsin, elastase, carboxypeptidase A, and B. The trypsin and chymotrypsin cleaving sites were mutated to investigate protection from pancreatic digestion and the specific activities of these mutants were evaluated. The six mutants displayed low specific activities compared to the wild-type, suggesting that the primary trypsin and chymotrypsin cleaving sites may be essential for catalytic reaction. The PAL mutants could therefore be applied as a pretreatment modality without susceptibility to proteolytic attack, however, additional modification for enhancing enzymatic activity is needed to reduce the Phe levels effectively.

• Korean Journal of Child Education & Care
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• v.18 no.2
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• pp.85-102
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• 2018

The purpose of this study is to determine the working conditions and demands of the assistant workforce at childcare centers, and to provide suggestions on policies for childcare teachers. To achieve the purpose of the study, a total of 190 assistant teachers, nursing helpers, alternative teachers and others were surveyed online during the month of August 2017. The survey examined the employment route and working motives, working conditions and environment, job and educational difficulties for analyzing the work conditions and demands of ancillary staff. For the analysis method, SPSS 12.0 was used to analyze frequency and difference. The main findings are as follows. First, childcare center assistants were able to work at their respective times, making it mandatory for them to enter the workforce, and making job openings for ancillary teachers. Second, 73.7% said the daily working hours were '4 hours to 8 hours' under the conditions and 57.9% said 'More than 510,000 won to less than 1 million won.' Average amount of rest time per day was about 30 minutes, and 17% had no rest periods. Third, based on the job and education status, ancillary personnel performed "infant and child guidance and interaction", "Cleaning and cleanliness related tasks" most actively, and "care for cleaning and cleanliness" and "care for morning and night care". Fourth, in the job trouble and difficulty, ancillary staff found it difficult to satisfy with wage related complaints and job insecurity, and the reason for agreeing to the non-regular workforce becoming a regular worker was found to be due to the stability of employment. Lastly, the most urgent tasks to solve the problem of non-regular workers were to fill the wage gap between regular and irregular workers, shorten the working hours and improve the working conditions. The policy implications are presented based on the above findings.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.75-85
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• 2009

This work proposes a 13b 100MS/s 0.13um CMOS ADC for 3G communication systems such as two-carrier W-CDMA applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs a four-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. Area-efficient high-speed high-resolution gate-bootstrapping circuits are implemented at the sampling switches of the input SHA to maintain signal linearity over the Nyquist rate even at a 1.0V supply operation. The cascode compensation technique on a low-impedance path implemented in the two-stage amplifiers of the SHA and MDAC simultaneously achieves the required operation speed and phase margin with more reduced power consumption than the Miller compensation technique. Low-glitch dynamic latches in sub-ranging flash ADCs reduce kickback-noise referred to the differential input stage of the comparator by isolating the input stage from output nodes to improve system accuracy. The proposed low-noise current and voltage references based on triple negative T.C. circuits are employed on chip with optional off-chip reference voltages. The prototype ADC in a 0.13um 1P8M CMOS technology demonstrates the measured DNL and INL within 0.70LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 64.5dB and a maximum SFDR of 78.0dB at 100MS/s, respectively. The ABC with an active die area of $1.22mm^2$ consumes 42.0mW at 100MS/s and a 1.2V supply, corresponding to a FOM of 0.31pJ/conv-step.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.250-259
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• 1982

The Larch was known unsuitable species for the wood cement board owing to its some inhibitory substances. Therefore this research was carried out to evaluate the effect of pretreatments and chemical additives on the properties of woodflake cement board from Japanese larch (Larix leptolepis) grown in Korea. In order to improve the board qualities, the woodflakes were treated by cold water or dilute NaOH solutions(0.1, 0.5, and 2.0%), and also some chemicals($CaCl_2$, $Al_2Cl_3$ and $Na_2SiO_4$) added to the wood cement mixture. The results obtained are summarized as follow; 1. The wood cement boards from the woodflake treated with 0.1% NaOH showed remarkable higher bending strengths and internal bonding strengths than those from the flake pretreated with cold water. 2. The bending strengths showed over $60kg/cm^2$, i.e. the standard strength of JIS A-5417, with pretreatments of NaOH over 0.1% and additive of $CaCl_2$ 3.0%. The maximum strengths showed at about 0.5 of every additives. 3. Addition of $CaCl_2$ and $Al_2Cl_3$, in the case of pretreated wood with NaOH above 0.1%, had effects on increasing the internal bonding strengths of sample boards. 4. The thickness swellings became decreasing along with the increasing NaOH pretreatment concentntration. 5. The equilibrium conditions of the sample boards pretreated with NaOH over 0.1% and added with $Al_2Cl_3$ and $CaCl_2$ were maintained at 9.0~10.5% moisture contents. 6. The specific gravity of the samples showed close relationships with strength properties.