• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.589-600
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• 2007

Statement of Problem: Titanium has many advantages of high biocompatibility, physical porperties, low-weight, low price and radiolucency, but it is incompatible with conventional dental porcelain due to titanium's oxidative nature. Many previous studies have shown that they used the method of sandblast surface treatment prior to porcelain application, the researchs are processing about the method of acid etching or surface coating. Purpose: The purpose of this research is to study the effect on bond strength between titanium and porcelain when using macro-surface treatment and micro-surface treatment and macro and micro surface treatment. Material and method: In this study, we evaluated the bond strength by using 3-point bending test based on ISO 9693 after classified 7 groups-group P : polished with #1200 grit SiC paper, group SS : sandblasted with $50{\mu}m$ aluminum oxides, group LS : sandblasted with $250{\mu}m$ alumium oxides, group HC : treated with 10% hydrochloric acid, group NF : treated with 17% solution of fluoric acid and nitric acid, group SHC : treated with 10% hydrochloric aicd after sandblsting with $50{\mu}m$ alumium oxides, group SNF treated with 17% solution of fluoric acid and nitric acid. Results : Within the confines of our research, the following results can be deduced. 1. Group SS which was sandblasted with $50{\mu}m$ aluminum oxides showed the highest bond strength of 61.74 MPa and significant differences(P<0.05). The bond strengths with porcelain in groups treated acid etching after sandblasting decreased more preferable than the group treated with sandblasting only. It gives significant differences(P<0.05). 2. After surface treatments, the group treated with sandblasting showed irregular aspect formed many undercuts, in the SEM photographs. The group treated with hydrochloric acid had the sharp serrated surfaces, the group treated with the solution of fluoric acid and nitric acid had the smooth surfaces, the group with sandblasting and hydrochloric acid had irrigular and porous structure, the group with sandblasting and the solution of fluoric acid and nitric acid had crater-like surfaces. But all of the groups treated with acid etching was not found and undercut. Conclusion: In above results, average surface roughness increase, bond strength also increase, but surface topographs influences more greatly on bond strengths.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.53-59
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• 2009

The purpose of this study was to clarify the clinical efficiency of tungsten carbide/carbon coating on obtaining optimal preload of abutment screw compared with non-coated screw in external-hex implant system. In the present work, rotational value and the compressive force between abutment and fixture of abutment screws without coating and with coating tightened to 30Ncm were measured. Mean compressive force of coated screw was 504.6N. Then uncoated screw was tightened to clamping the abutment and the implant to 504.6N, and the tightening torque value and the rotational value was recorded. The following conclusions were drawn within the limitation of this study. Compressive force of coated screw was higher than that of uncoated screw after tightening at 30Ncm. The tightening torque that was nedeed to clamping the uncoated screw equal to coated screw tightened to 30Ncm was 55.6Ncm. In case of equal compressive force, there was no significant difference in rotation value between coated and uncoated screw.

• Korean Journal of Occupational Health Nursing
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• v.10 no.1
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• pp.74-92
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• 2001

This study was carried out to investigate the types of health documents for nurses, the content of informations in the documents, and writing behaviors of occupational health nurses. Health documents were collected from 7 nurses who were working in 7 group occupational health agencies (GOHA) located at Seoul and Inchon area in Korea. The collected health documents written in January to June 1999 were analyzed, and revealed the following results. 1) The occupational health nurses were using 9 to 18 different types of health documents. The contents of the documents were considered quite similar to each other with slightly different headings and items to record. Among different types of health documents. Health Management Card for Workplace', Nursing performance sheet and Workplace environmental checklist were in common among nurses and were used for content analysis. 2) The 'Health Management Card for Workplace' was the only formal sheet of small-scale-enterprises (SSE) for health management, in which health and safety related information was recorded. The information on nursing services were recorded on the Nursing performance sheet, which has slightly different names on each type with similar contents. The Workplace environment checklist was for the information on general work environment management and mainly status of workplace hygiene. This checklist is to be used by or with nurses among the 3 types health professional team such as doctor, hygienist, and nurse, but it seemed not being used frequently by nurses. 3) Analysis on recording tendencies of nurses revealed that the writing styles of occupational health nurses were associated with 'memo' using a few number of words and short sentences. The amount of information by this kind of recording style was considered not enough for health management situation. The possible reasons for nurses to use this writing style might be insufficient time for recording and improper designed format of health documents. Because nurses working in SSE spend more time on the roads to visit workplaces, nurses may not found enough time for recording properly within their working time. In addition, the health records were designed to focus on the frequency of nurse's performance in certain types of work rather than on the method they used to deal with health problems. In conclusion, this study suggests that some steps are necessary to develop health documents and recording system which is appropriate to occupational health nurses. The educational need for nurses on appropriate recording behavior is also recommended.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12B
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• pp.1183-1191
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• 2010

In this paper, I propose an adaptive OFDM CP length algorithm for in PLC systems for smart grid. The proposed scheme calculates the channel delay information at the CP controller of the receiver by taking correlation between a received data frame and the following delayed one. The CP controller, immediately, feeds back the channel delay information to the transmitter. Then, the transmitter adapts CP length for next data frame. As an impulsive noise model, Middleton Class A interference model was employed. The performance is evaluated in terms of packet data rate, cumulative packet data rate, and bit error rate (BER). The simulation results showed data gain (which is the amount of the reduced bits) gets larger as the number of packets increase, but the amount of data gain reduced as the number of branches ($N_{br}$) increase. In respects of BER for the cases $N_{br}$ is 3, 4, and 5, performance of the adaptive CP length algorithm and the fixed CP scheme are similar. Therefore, it is confirmed the proposed scheme achieved data rate increment without BER performance reduction compared to the conventional fixed CP length scheme.

• Korea journal of population studies
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• v.21 no.2
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• pp.37-57
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• 1998

In recent, Korea introduced the local self-government system. And the local government tried to establish and implement plans for women. Those plans were established on the basis of not the particular environments of regional societies but similar policies of central government. Despite of geographical migrations, we can find differences of population structure and economic status among regions. As the result, most of regional policies for women were ineffective. This paper examines population structure and economic status of women by regions and recommends the long and medium direction for local policies for women. For analysis, it utilizes the 2% sample data-set of National Statistical Office's '1995 Population and Housing Census' in Korea. The findings of this paper are summarized as following; Firstly, the dependency rate of Chungchong-do, Cholla-do, Kyongsangnam-do will reach about 45% in 2000. Therefore, as soon as possible, those local government should establish the labor policies to enhance the economically active participation rate of the elderly persons and welfare policy for them. Secondly, the level of women's economic participation. Thus, local governments should set up labor market policies for women according to regional situations. For examples, in Kyonggi-do, Seoul, Daejeon, Daeku which unemployment rate of the highly educated women are relatively high, those local governments should seek the measures to tackle unemployment problem of them. Thirdly, due to the differences regional economic structure, women's employment structures differed also by region. Hence, local governments should formulate suitable plans to consider the working status of regional women's workers.

• Journal of the Korean Geophysical Society
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• v.10 no.1
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• pp.1-12
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• 2007

A method to quickly estimate broadband moment magnitudes (Mwp) to warn regional and teleseismic tsunamigenic earthquakes is tested for application of the method to the different seismic observation environment. In this study, the Mwp is calculated by integrating far-field P-wave or pP-wave of vertical component of displacement seismograms in time domain from earthquakes, having magnitude greater than 5.0 and occurred in and around the Korean peninsula from 2000 to 2006. We carefully set up the size of the time window for the computations to exclude S wave phases and other phases following after the P wave phase. The P wave velocities and the densities from the averaged Korean crustal model are used in the computations. Instrumental correction was performed to remove dependency on the seismograph. The Mwp after the instrumental correction is about 0.1 greater than the Mwp before the correction. The comparison of our results to the those of foreign agencies such as JMA and Havard CMT catalogues shows a higher degree of similarity. Thus our results provide an effective tool to estimate the earthquake size, as well as to issue the necessary information to a tsunami warning system when the effective earthquake occurs around the peninsula.

• Journal of Ginseng Research
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• v.13 no.1
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• pp.42-48
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• 1989

The binding of bay region diol-epoxides of polycyclic aromatic hydrocarbons (PAHs) to target tissue DNA is thought to be essential for the initiation of cancer by these compounds. In this study we investigated the effect of polyacetylenes such as panaxynol and panaxydol on the formation of benzo(a)pyreno (BP)-metabolite-DNA adduct in the liver of ICR mice. Treatment of mice by i.p. administration of polyacetylenes produced a marked reduction in BP metabolite binding to DNA in vitro. Following i.v. administration of (3H)BP(300, ${\mu}$Ci/21 nmoles/0.1 nt DMSO) to mice, radioactivity was detected in the DNA of the liver in vivo. The result of tentative identification of the 4 peaks between the two standard markers for high pressure liquid chromatography showed that the peaks. I, II, III, and IV were BP-phenol oxide-DNA adduct (or BP-diol-epoxide-dCyt. adduct), (-) BP$.$diolepoxide I:dGuO adduct, (+) BP-diol-epoxide I: dGuo adduct, and BP-diol-epoxide II:dGuO adduct, respectively. The minor adduct, (-) BP-diol epoxide I: dGuo was reduced to 6971 of the amount of the control, while the major adduct, (+) BP-diolepoxide I: dGuO(peak II) which was produced from (-) BP-7, 8-diol was reduced to 78% of that of the control. The amount of the minor adduct, BP-diol-epoxide II:dGuo adduct(peak IV) which formed from (+) BP-7, 8-diol was 58% of the control. These results show that the panaxydol is more related to inhibition of the formation of the minor ad- ducts than of the major adducts, which were generally produced from ($\pm$) BP-7, 8-dihydro-dials.

• Journal of The Korean Society of Clinical Toxicology
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• v.13 no.1
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• pp.50-54
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• 2015

Podostroma cornu-damae is a rare species of fungus belonging to the Hyocreaceae family. Its fruit body is highly toxic, as it contains trichothecene mycotoxins. The morphology is similar to that of immature Ganoderma lucidum, making identification difficult for non-experts. We experienced such a case of a 56- year-old male who picked and consumed podostroma cornu-damae, and consumed. Later that day, he developed digestive system symptoms, including nausea, vomiting, and abdominal pain. He presented to the emergency room (ER), there were no abnormal physical findings, symptoms improved after gastric lavage, and the patient voluntarily discharged himself on the same day. The following day, as the symptoms gradually deteriorated, he was admitted via the ER. He was presented with severe pancytopenia, alopecia, desquamation of skin, and acute renal failure. He recovered without any complications after conservative care, antibiotics therapy, and granulocyte colony stimulating factor administration. The most commonly reported complications of podostroma cornu-damae intoxication were reported pancytopenia, infection, disseminated intravascular coagulation, acute renal failure, etc. since Prevention is especially important because its toxicity can be lethal and there is no particular treatment to date, prevention is especially important. Promotion and education for the public are needed.

• Clean Technology
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• v.26 no.2
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• pp.96-101
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• 2020

In this paper, the commercial feasibility of trigeneration, producing heat, power, and hydrogen (CHHP) and using biogas derived from macroalgae (i.e., seaweed biomass feedstock), are investigated. For this purpose, a commercial scale trigeneration process, consisting of three MW solid oxide fuel cells (SOFCs), gas turbine, and organic Rankine cycle, is designed conceptually and simulated using Aspen plus, a commercial process simulator. To produce hydrogen, a solid oxide fuel cell system is re-designed by the removal of after-burner and the addition of a water-gas shift reactor. The cost of each unit operation equipment in the process is estimated through the calculated heat and mass balances from simulation, with the techno-economic analysis following through. The designed CHHP process produces 2.3 MW of net power and 50 kg hr^-1 of hydrogen with an efficiency of 37% using 2 ton hr^-1 of biogas from 3.47 ton hr^-1 (dry basis) of brown algae as feedstock. Based on these results, a realistic scenario is evaluated economically and the breakeven electricity selling price (BESP) is calculated. The calculated BESP is ¢10.45 kWh^-1, which is comparable to or better than the conventional power generation. This means that the CHHP process based on SOFC can be a viable alternative when the technical targets on SOFC are reached.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.287-294
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• 2005

In this paper, an optical true time-delay (TTD) for two-dimensional (2-D) phased array antennas (PAAs), composed of a multi-wavelength optical source and a fiber optic delay line matrix consisting of $2\times2$ optical switches with optical fiber connected between cross ports, has been proposed. A 2-bit $\times4-bit$ optical TTD for 10-GHz 2-D PAAs has been implemented by cascading a wavelength dependent TTD (WD-TTD) and a wavelength independent TTD (WI-TTD). The unit time delay for WD-TTD and WI-TTD have been chosen as ${\Delta}T=12ps$ and $\Delta\tau=6ps$, respectively. Time delay have been measured at all radiation angles. The maximum delay error for WD-TTD was measured to be 3 ps due to jitter incurred from gain switching. For the case of WI-TTD, error was within ${\pm}\;1\;ps$. The proposed optical TTD for a 2-D PAA has the following advantages: 1) higher gain compared to one-dimensional linear PAAs, 2) stabilization of optical power and wavelength by using a multi-wavelength optical source, and 3) fast beam scan and simple operation due to electronic control of the $2\times2$ optical switches matrix on a column-by-column basis.