• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.346-352
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• 2020

It has been about 30 years since women students entered the Maritime College at Mokpo National Maritime University (MMU) and Korea Maritime & Ocean University to train as maritime seafarers. The women have been choosing a maritime college regardless of the Boarding Service Reserve System. Therefore, it is necessary to continuously study the motivation for admission, preferences for boarding, and desired career paths to guide the distinction and vision of maritime colleges. Accordingly, this study conducted a questionnaire survey on 93 women students attending the Maritime College at MMU. Of the respondents, 35.5 % said that they enrolled to become maritime officials and 30.1 % to become maritime seafarers. In addition to the current training for maritime seafarers, additional courses are required to train maritime experts. The study found that 88.2 % of the respondents thought that women's embarkation was more difficult than usual. It is considered that a systematic education program is needed for the onboard life of women maritime seafarers in schools and shipping companies. It was found that 69.6 % of the respondents preferred to embark as seafarers after graduation. After graduating from university, 32.3 % of the respondents said that they preferred to become navigation officers or engineers. It was also found that 24.7 % preferred to become marine-related civil servants / professionals, and 18.3 % preferred to become marine police. From the total, 83.9 % hoped for careers in marine-related fields. It is, therefore, necessary to organize courses and further education according to the motives for admission and preferred occupations of women students.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.3 s.345
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• pp.21-32
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• 2006

A new SRAM circuit with row-by-row activation and low-swing write schemes is proposed to reduce switching power of active cells as well as leakage one of sleep cells in this paper. By driving source line of sleep cells by $V_{SSH}$ which is higher than $V_{SS}$, the leakage current can be reduced to 1/100 due to the cooperation of the reverse body-bias. Drain Induced Barrier Lowering (DIBL), and negative $V_{GS}$ effects. Moreover, the bit line leakage which may introduce a fault during the read operation can be eliminated in this new SRAM. Swing voltage on highly capacitive bit lines is reduced to $V_{DD}-to-V_{SSH}$ from the conventional $V_{DD}-to-V_{SS}$ during the write operation, greatly saving the bit line switching power. Combining the row-by-row activation scheme with the low-swing write does not require the additional area penalty. By the SPICE simulation with the Berkeley Predictive Technology Modes, 93% of leakage power and 43% of switching one are estimated to be saved in future leakage-dominant 70-un process. A test chip has been fabricated using $0.35-{\mu}m$ CMOS process to verify the effectiveness and feasibility of the new SRAM, where the switching power is measured to be 30% less than the conventional SRAM when the I/O bit width is only 8. The stored data is confirmed to be retained without loss until the retention voltage is reduced to 1.1V which is mainly due to the metal shield. The switching power will be expected to be more significant with increasing the I/O bit width.

• Journal of Oral Medicine and Pain
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• v.33 no.2
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• pp.159-166
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• 2008

An ideal anti-bacterial medication for oral infection requires selective effect on pathogens causing dental caries and periodontal disease but not on normal flora. In addition, it should be less toxic for human and even for environment. This study was to seek such a natural anti-bacterial medication and thus anti-bacterial effect of Hamamelis virginiana was evaluated. Many recent researches on the anti-bacterial effect of natural plant extract and essential oil have reported that natural products can be used as medication for prevention and restrainment of dental caries, halitosis and periodontitis. It has been also reported that Hamamelis virginiana has anti-bacterial effect on Porphyromonas gingivalis, Fusobacterium nucleatum, Capnocytophaga gingivalis, Veilonella parvula, Eikenella corrodens, Peprostreptococcus micros, and Actinomyces odontolyticus. This study evaluated anti-bacterial effect of Hamamelis virginiana on Streptoccoccus mutans, Haemophylus actinomycetemcomitans, and Klebsiella pneumoniae to expand its anti-bacterial effect on other important oral pathogens and eventually to develop its oral care products or apply to clinical purpose. In this study, anti-bacterial tests for antibiotic disk susceptibility, minimal inhibitory concentration and minimal bactericidal concentration were performed to evaluate anti-bacterial effect of Hamamelis virginiana against Streptoccoccus mutans, Haemophylus actinomycetemcomitans, and Klebsiella pneumoniae. The results showed that Hamamelis virginiana has anti-bacterial effect on all pathogen strains tested in this study and furthermore Hamamelis virginiana possesses bactericidal effect other than bacteriostatic effect on Streptoccoccus mutans, Haemophylus actinomycetemcomitans, Klebsiella pneumoniae. This study indicates that a natural anti-bacterial medication for oral diseases can be developed using Hamamelis virginiana.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.12 no.1
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• pp.71-78
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• 2001

Objectives：Few studies have examined the psychiatric properties or child developmental problems associated with inversion of chromosome 9. The purpose of this study is to examine the psychiatric properties of child patients who have inversion of chromosome 9, focused on behavioral problems and child developmental problems like motor or language developmental delay, intellectual impairment, and growth retardation. Methods：1) The authors examined the cases referred for cytogenetic examination from 1984 to 2000 at Seoul National University Hospital in Korea. The cases with the examination result of inversion of chromosome 9 were collected and informations about the departments which referred and the main reasons for referral were also checked. 2) 12 child subjects with inversion of chromosome 9 and their parents underwent psychiatric interview and parent questionnaire(child and adolescent past history questionnare, CBCL). 45 normal students whose sex and age were matched to patients were selected as a control group. Results：1) There were 165 cases of inversion of chromosome 9. The major departments which referred were Obstetrics and Gynecology(47.3%), Pediatrics(23.6%) and Child and Adolescent Psychiatry(17.0%). The major reasons for referral from the Pediatrics and the Child and Adolescent Psychiatry department (67 cases total) were intellectual impairment(35.8%), language or motor developmental delay(31.3%), suspected Fragile X syndrome(23.9%), and growth retardation(20.9%). 2) Compared to normal control group, the rate to be included in the clinical range with regard to the social problems profile was higher in patient group according to the CBCL results. The patient group had language and motor developmental delay. Conclusion：There is a possibility of inversion of chromosome 9 to be associated with child developmental problems or behavioral problems. This study is the first approach to evaluate the developmental aspects associated with inversion of chromosome 9.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.193-204
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• 1998

The single crystal of the $LiTaO_3$has large electro-optic effects, so it is applied to optical switch, acousto-optic deflector, and optical memory device as hologram using photorefractive effect. In this study, optic-grade undoped $LiTaO_3$and Fe:LiTaO$LiTaO_3$single crystals were grown by the Czochralski method and optical transmission and absorption spectrums were measured in the wavelength of UV-VIS range. The curie temperature was determined with DSC and by measuring capacitance for the grown undoped crystal and ceramic powder samples of various Li/Ta ratio. In case of having a 48.6 mol% $Li_2O$ as a starting Li/Ta ratio, the results of concentration variations were below 0.01 mol% $Li_2O$ all over the crystal, so it was confirmed that $LiTaO_3$single crystals were grown under congruent melting composition having optical homogeneity. The curie temperature of the Fe:$LiTaO_3$crystal was increased with increased with increased doped Fe concentrations;by the ratio of $7.5^{\circ}C$ increase per Fe 0.1 wt%. Also, the optical transmittance was about 78 %, which was sufficient for optical device.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.229-236
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• 2014

A stoichiometric mixture of evaporating materials for $MnAl_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $MnAl_2S_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $410^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The temperature dependence of the energy band gap of the $MnAl_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=3.7920eV-5.2729{\times}10^{-4}eV/K)T^2/(T+786 K)$. In order to explore the applicability as a photoconductive cell, we measured the sensitivity (${\gamma}$), the ratio of photocurrent to dark current (pc/dc), maximum allowable power dissipation (MAPD) and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in S vapour compare with in Mn, Al, air and vacuum vapour. Then we obtained the sensitivity of 0.93, the value of pc/dc of $1.10{\times}10^7$, the MAPD of 316 mW, and the rise and decay time of 14.8 ms and 12.1 ms, respectively.

• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.71-76
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• 2014

There is to be virtually impossible to solve the very large digits of prime number p and q from composite number n=pq using integer factorization in typical public-key cryptosystems, RSA. When the public key e and the composite number n are known but the private key d remains unknown in an asymmetric-key RSA, message decryption is carried out by first obtaining ${\phi}(n)=(p-1)(q-1)=n+1-(p+q)$ and then using a reverse function of $d=e^{-1}(mod{\phi}(n))$. Integer factorization from n to p,q is most widely used to produce ${\phi}(n)$, which has been regarded as mathematically hard. Among various integer factorization methods, the most popularly used is the congruence of squares of $a^2{\equiv}b^2(mod\;n)$, a=(p+q)/2,b=(q-p)/2 which is more commonly used then n/p=q trial division. Despite the availability of a number of congruence of scares methods, however, many of the RSA numbers remain unfactorable. This paper thus proposes an algorithm that directly and immediately obtains ${\phi}(n)$. The proposed algorithm computes $2^k{\beta}_j{\equiv}2^i(mod\;n)$, $0{\leq}i{\leq}{\gamma}-1$, $k=1,2,{\ldots}$ or $2^k{\beta}_j=2{\beta}_j$ for $2^j{\equiv}{\beta}_j(mod\;n)$, $2^{{\gamma}-1}$ < n < $2^{\gamma}$, $j={\gamma}-1,{\gamma},{\gamma}+1$ to obtain the solution. It has been found to be capable of finding an arbitrarily located ${\phi}(n)$ in a range of $n-10{\lfloor}{\sqrt{n}}{\rfloor}$ < ${\phi}(n){\leq}n-2{\lfloor}{\sqrt{n}}{\rfloor}$ much more efficiently than conventional algorithms.

• Journal of Life Science
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• v.20 no.10
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• pp.1532-1537
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• 2010

This study compared the inhibitory effects of methanol extracts from yellow and black soybeans (black soybean, Seomoktae and Seoritae) on mutagenicity using the Ames test and growth of human cancer cells (AGS human gastric adenocarcinoma, HT-29 human colon cancer, Hep 3B hepatocellular carcinoma cells). In the Ames test system using Salmonella typhimurium TA100, aflatoxin $B_1$ ($AFB_1$)-induced mutagenicity was significantly inhibited by treatments with the methanol extracts from either yellow or black soybeans in a dose dependent manner (p<0.05). The methanol extracts from various black soybeans tended to have a greater inhibitory effect compared to those from yellow soybeans. As for N-methyl-N'-nitro-N-nitrosoguamidine (MNNG)-induced mutagenicity, the methanol extracts (5 mg/assay) from black soybean, Seomoktae and Seoritae showed 51%, 61% and 53% inhibitory rates, respectively, indicating that Seomoktae, a type of black soybean, had a stronger antimutagenic activity against mutagens (both $AFB_1$ and MNNG). Methanol extracts from black soybeans showed an inhibitory rate of greater than 50% on the growth of human cancer cells (AGS, HT-29 and Hep 3B) and the inhibition was more effective in the methanol extract from Seomoktae. Our results suggested that the methanol extracts from black soybeans showed stronger inhibitory effects on mutagenicity and growth of cancer cells than those from yellow soybean. It is concluded that intake of black soybean can be recommended for improving health.

• Journal of the Korean Geotechnical Society
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• v.28 no.5
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• pp.13-25
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• 2012

Ground anchor method is one of the most popular reinforcing technology for slope in Korea. For the health monitoring of slope which is reinforced by permanent anchor for a long period, monitoring of the tension force of ground anchor is very important. However, since electromechanical sensors such as strain gauge and V/W type load cell are also subject to long-term risk as well as suffering from noise during long distance transmission and immunity to electromagnetic interference (EMI), optical FBG sensors embedded tendon was developed to measure strain of 7-wire strand by embedding FBG sensor into the center king cable of 7-wire strand. This FBG sensors embedded tendon has been successfully applied to measuring the short-term anchor force. But to adopt this tendon to long-term monitoring, temperature compensation of the FBG sensors embedded tendon should be done. In this paper, we described how to compensate the effect in compliance with the change of underground temperature during long-term tension force monitoring of ground anchors by using optical fiber sensors (FBG: Fiber Bragg Grating). The model test was carried out to determine the temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon. The determined temperature sensitivity coefficient ${\beta}^{\prime}=2.0{\times}10^{-5}/^{\circ}C$ was verified by comparing the ground temperatures predicted from the proposed sensor using ${\beta}^{\prime}$ with ground temperatures measured from ground thermometer. Finally, temperature compensations were carried out based on ${\beta}^{\prime}$ value and ground temperature measurement from KMA for the tension force monitoring results of tension type and compression type anchors, which had been installed more than 1 year before at the test site. Temperature compensated tension forces are compared with those measured from conventional load cell during the same measuring time. Test results show that determined temperature sensitivity coefficient (${\beta}^{\prime}$) of FBG sensors embedded tendon is valid and proposed temperature compensation method is also appropriate from the fact that the temperature compensated tension forces are not dependent on the change of ground temperature and are consistent with the tension forces measured from the conventional load cell.

• Journal of Korean Home Economics Education Association
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• v.29 no.2
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• pp.1-22
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• 2017

The purpose of this research is to share the experience of reflective practice of a Home Economics teacher professional learning community(PLC) operator and to share better suggestions through reflection on PLC operation. All conversation in the 18 sessions of the PLC totally from May 31st 2013 to May 19th 2014 was recorded and transcribed. All materials of PLC activity were qualitatively analysed. Its themes were grounded on its coding and categorization scheme. Findings and conclusions of this study are as followings. The experience of learning the PLC for a year has found that it is the power to keep the PLC alive: courage and anxiety to face anxiety and anxiety about new challenges, the importance of theme selection, a teacher with a reckless challenge, shares of becoming a leader. Through reflection, I learned that concerns require attention to other teachers and the need for a 'New Round' for ongoing meetings. I, as a operator, did not fully consider participant's different interest as well as a program for a new round due to the lack of management experience. It led to the low participations in latter sessions of PLC. Suggestions are put as solutions to improve these problems; (1) grouping participants by school levels when collecting participants, (2) setting operation period and program applying participants' opinions, and (3) operating short-term PLC with certain themes to immerse reaching goal and satisfaction in short time.