• Journal of The Korean Astronomical Society
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• v.49 no.5
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• pp.199-208
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• 2016

We present photometric results of the δ Sct star V1162 Ori, which is extensively monitored for a total of 49 nights from mid-December 2014 to early-March 2015. The observations are made with three KMTNet (Korea Microlensing Telescope Network) 1.6 m telescopes installed in Chile, South Africa, and Australia. Multiple frequency analysis is applied to the data and resulted in clear detection of seven frequencies without an alias problem: five known frequencies and two new ones with small amplitudes of 1.2-1.7 mmag. The amplitudes of all but one frequency are significantly different from previous results, confirming the existence of long-term amplitude changes. We examine the variations in pulsation timings of V1162 Ori for about 30 years by using the times of maximum light obtained from our data and collected from the literatures. The O − C (Observed minus Calculated) timing diagram shows a combination of a downward parabolic variation with a period decreasing rate of (1/P)dP/dt = −4.22 × 10⁻⁶ year⁻¹ and a cyclic change with a period of about 2780 days. The most probable explanation for this cyclic variation is the light-travel-time effect caused by an unknown binary companion, which has a minimum mass of 0.69 M_⊙. V1162 Ori is the first δ Sct-type pulsating star of which the observed fast period decrease can be interpreted as an evolutionary effect of a pre-main sequence star, considering its membership of the Orion OB 1c association.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.759-769
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• 2015

Diode rectifiers are very popular in industry. However, they include large low-order harmonics in the input current and do not satisfy harmonic current content restrictions. To reduce the harmonics to the power system, several methods have been introduced. It is heavy and expensive solution to use passive filters as the solution for high power application. Another solution for the harmonic filter is utilization of active filter, but it is too expensive solution. Diode rectifiers with configurations using switching device have been introduced, but they are very complicated. The combined 12-pulse diode rectifier with the square auxiliary voltage supply has been introduced. It has the advantages that auxiliary circuit is simple and inexpensive compared to other strategies. The advanced auxiliary voltage supply in this thesis is presented as a new solution. When the square auxiliary voltage supply applied, the improvement of THD is 6~60[%] in whole load range. But when the advanced auxiliary voltage supply applied, it shows stable and excellent reduction effect of THD as 57~71[%]. Especially, for the case with 10[%] load factor, reduction effect of THD has little effect as 6[%] in the case of inserting a square auxiliary voltage supply. But when the proposed new solution applied, reduction effect has excellent effect as 71[%]. Theoretical analysis of the combined 12-pulse diode rectifier with the advanced auxiliary voltage supply is presented and control methods of the auxiliary supply is proposed. The reduction in the input current harmonics is verified by simulation using software PSIM.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1273-1279
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• 2016

Production of iodine-131 by neutron activation of tellurium in tellurium dioxide ($TeO_2$) material requires a target that meets the safety requirements. In a radiopharmaceutical production unit, a new lid for a can was designed, which permits tight sealing of the target by using tungsten inert gaswelding. The leakage rate of all prepared targets was assessed using a helium mass spectrometer. The accepted leakage rate is ${\leq}10^{-4}mbr.L/s$, according to the approved safety report related to iodine-131 production in the TRIGA Mark II research reactor (TRIGA: Training, Research, Isotopes, General Atomics). To confirm the resistance of the new design to the irradiation conditions in the TRIGA Mark II research reactor's central thimble, a study of heat effect on the sealed targets for 7 hours in an oven was conducted and the leakage rates were evaluated. The results show that the tightness of the targets is ensured up to $600^{\circ}C$ with the appearance of deformations on lids beyond $450^{\circ}C$. The study of heat transfer through the target was conducted by adopting a one-dimensional approximation, under consideration of the three transfer modes-convection, conduction, and radiation. The quantities of heat generated by gamma and neutron heating were calculated by a validated computational model for the neutronic simulation of the TRIGA Mark II research reactor using the Monte Carlo N-Particle transport code. Using the heat transfer equations according to the three modes of heat transfer, the thermal study of I-131 production by irradiation of the target in the central thimble showed that the temperatures of materials do not exceed the corresponding melting points. To validate this new design, several targets have been irradiated in the central thimble according to a preplanned irradiation program, going from4 hours of irradiation at a power level of 0.5MWup to 35 hours (7 h/d for 5 days a week) at 1.5MW. The results showthat the irradiated targets are tight because no iodine-131 was released in the atmosphere of the reactor building and in the reactor cooling water of the primary circuit.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.5
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• pp.324-333
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• 2013

Recently, rudder erosion due to cavitation has been frequently reported on a semi-spade rudder of a high-speed large ship. This problem raises economic and safety issues when operating ships. The semi-spade rudders have a gap between the horn/pintle and the movable wing part. Due to this gap, a discontinuous surface, cavitation phenomenon arises and results in unresolved problems such as rudder erosion. In this study, we made a rudder model for 2-D experiments using the NACA0020 and also manufactured gap flow blocking devices to insert to the gap of the model. In order to study the gap flow characteristics at various rudder deflection angles($5^{\circ}$, $10^{\circ}$, $35^{\circ}$) and the effect of the gap flow blocking devices, we carried out the velocity measurements using PIV(Particle Image Velocimetry) techniques and cavitation observation using high speed camera in Seoul National University cavitation tunnel. To observe the gap cavitation on a semi-spade rudder, we slowly lowered the inside pressure of the cavitation tunnel until cavitation occurred near the gap and then captured it using high-speed camera with the frame rate of 4300 fps(frame per second). During this procedure, cavitation numbers and the generated location were recorded, and these experimental data were compared with CFD results calculated by commercial code, Fluent. When we use gap flow blocking device to block the gap, it showed a different flow character compared with previous observation without the device. With the device blocking the gap, the flow velocity increases on the suction side, while it decreases on the pressure side. Therefore, we can conclude that the gap flow blocking device results in a high lift-force effect. And we can also observe that the cavitation inception is delayed.

• Journal of muscle and joint health
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• v.7 no.2
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• pp.281-293
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• 2000

This study was conducted to identify the relationships among self-care agency, family support, qualify of life in patients with rheumatoid arthritis. The subjects were 120 rheumatoid arthritis patients who attended RA O.P.D. at a university hospital, located in Daegu city, from 10th of May in 1998 to 30th of July in 1998. Three structure questionnaires were administered for explore three main research variables; 소향숙's self-care agency scale, 강현숙's family support scale, and 김종임's quality of life scale of RA patien. Data analysis was conducted with SPSS program including percentage, mean, standard deviation, mean score, Pearson Correlation Coefficient, multiple regression, and Cronbach's Alpha. Results are summarized as follows; 1. The mean of RA patient's self-care agency was 136.62, the mean of family support 37.38, and the mean of qualify of life 134.41. 2. Subject's self-care agency was positively correlated with family support(r=.2446) and with quality of life(r=.4341). Subject's family support was positively correlated with quality of life(r=.2630). 3. Stepwise multiple regression was used to determine the predictors of subject's quality of life. Significant predictors for subject's quality of life were self-care agency(t=4.873 p=0.0000), family support(t=4.480 p=0.0000) and the severity of arthralgia(t=-3.838, p=0.0002). The number of joints involved and the periods of illness did not show significant contribution to subject's quality of life. Self-care agency, family support, and family support explained 40. 39% of the variance in RA patient's quality of life. Given this results, it is suggested that a repeated study to measure RA patient's self-care practice in their own life may be needed to develope and validate an optimum level of nursing intervention for RA patient with which family support will be encouraged and patient's self-care agency will be facilitated.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.57-66
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• 1990

The author conducted a dental survey of college girl students and compared with that of college students 20 years and 10 years ago which based on the same criteria. The items of this survey included the prevalence of dental caries, DMFT and the kinds of restored materials. College girl students 2,294 were examined in May 1988, with the recommended criteria and method of W.H.O.. Among them, the data of 2,243 were analyzed and compared with the data of 1968 and 1978. The following results were obtained : 1. The average number of present teeth was $28.86{\pm}1.65$, which does not show much difference when compared to $29.00{\pm}1.94$ of 1968 and $28.97{\pm}1.64$ of 1978. 2. The prevalence of dental caries was 86.22%, which increased in comparison to 83.25% of 1968 and 84.92% of 1978. 3. DMF index was 19.98, which considerably increased in comparison to 14.56 of 1968 and 15.51 of 1978. 4. The number of DMFT was $5.75{\pm}5.04$ per student. Compared to $4.23{\pm}3.88$ of 1968 and $4.49{\pm}3.69$ of 1978, there is a considerable increase. I) The average number of decayed(D) teeth was $1.14{\pm}1.63$, which decreased from $1.16{\pm}1.57$ of 1968 and $2.09{\pm}2.16$ of 1978. II) The average number of missing(M) teeth was $0.23{\pm}0.73$, which also decreased from $0.69{\pm}1.11$ of 1968 and $0.32{\pm}0.79$ of 1978. III) The average number of filled(F) teeth was $4.39{\pm}4.91$, which increased from $2.38{\pm}3.33$ of 1968 and $2.09{\pm}3.17$ of 1978. 5. According to the analysis of filling material, filling baby including amalgam, gold inlay, resin, silicate cement and paladium inlay was 90.5%, which increased in comparison to 72.8% of 1968 and 83.6% of 1978. Among them, amalgam occupied 62.93%, which showed the most increase. On the other hand, crown and bridge was 6.5%, 3.0%, respectively, which showed continuous decrease from 12.1%, 15.1% of 1968 and 8.7%, 7.7% of 1978. Therefore, the prosthodontic treatment reduced due to the decrease of tooth extraction. In contrast, there is continuous increase of conservative treatment which maintaining natural tooth.

• KSBB Journal
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• v.10 no.4
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• pp.349-356
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• 1995

To produce PHA(polyhydroxyalkanoic acid) from microbr, dozens of microorganism have been screened from sewage sludge. Selected a strain HJ out of 50 strains of PHA producing bacteria has a capability of accumulating large amounts of PHB/HV copolymer when grown in batch culture with a single carbon source (glucose) that was not generally considered as precursor of hydroxyvalerate monomer unit. The strain HJ was identified as the genus Pseudomonas with respect to morphological, cultural, and biochemical characteristics. The optimal temperature and pH for cell growth were $37^{\circ}C$ and 7.0. The optimal medium compositions for cell growth were glucose 1% as a carbon source, (NH4) 2SO4 0.2% as a nitrogen source, K2HPO4 0.3%, and KH2PO4 0.45%. TO investigate she optimal condition for PHA production two-step cultivation method was employed. PHA production was inducted by deficiency of NH4+, SO4-2, Mg+2. Besides carbon source, deficiency of all nutrients stimulated PHA productivity but deficiency of NH4+ stimulated the most HV monomer content. The highest PHA production was C/N molar ratio 95.2. Pseudomonas sp. HJ was also able to pyoduc PHB/HV copolymer when cultivated on alkane, alkanoate, alcohol as carbon sources. The contents of PHA and she proportions of hydroxyvalerate monomer units varied depending on the carbon sources. Especially Pseudomonas sp. HJ was able to incorporate hydroxyvalerate into PHB/HV to level as high as from 49 to 74 mol% when grown in a medium containing hexadecane and propionate. The purified PHA was identified PHB/HV copolymer by HNMR analysis.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.1
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• pp.29-37
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• 2013

The purpose of this study is to suggest the potential domestic and international market conditions vehicles for people with disabilities through a review of the literature and internet resources, and to propose a road map developing South Korean vehicles for people with disabilities taking into consideration the current state of domestic and international technology and the usage of the vehicles for people with disabilities depending on the type of disability. The results of the study are as follows: First, vehicles for people with disabilities safety standards of South Korea do not meet the safety standards of developed countries and the technology of development related vehicles for people with disabilities is not as advanced as that of developed countries. Vehicles for people with disabilities installation methods, specifications, features and safety standards should be designed to be more similar to those of Japan and the United States. Second, vehicle modifications for people with disabilities will become more common as measures directed at promoting the welfare of people with disabilities, such as travel and transportation measures, employment opportunities, education, and funding for vehicle modifications, are implemented along with laws, such as The Americans with Disabilities Act, The British Disability Discrimination Act, and Japan's barrier-free transport law, that protect people with disabilities generally. Third, through a comparative analysis of domestic and international market conditions and demands of people with disabilities in vehicle modifications, important things to pay attention by purchasing a modified vehicle for people with disabilities are the employment rate for people with disabilities and monthly income. To enable this, government agencies and industry bodies should work together through the revision of the current Disability Welfare Act or the enactment of the special law for guiding principles of Disability Welfare Act. Through the future changes in vehicles for people with disabilities-related system or society of South Korean, the annual demand of the vehicles is expected to be more than 10,000.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.39
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• pp.26.1-26.10
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• 2017

Background: The impairment of the appearance is a major problem for patients with carcinomas of the oral cavity. These patients want to recover their preoperative facial appearance. Some do not realize that this is not always possible and hence develop a desire for further cosmetic and reconstructive surgery (CRS) which often causes psychological problems. Method: The desire of patients for CRS (N = 410; 26%) has been acquired in this $D{\ddot{O}}SAK$ rehab study including multiple reasons such as medical, functional, aesthetic and psychosocial aspects. They relate to the parameters of diagnosis, treatment and postoperative rehabilitation. Patients without the wish for CRS (N = 1155; 74%) served as control group. For the surgeons, knowledge of the patient's views is relevant in the wish for CRS. Nevertheless, it has hardly been investigated for patients postoperatively to complete resection of oral cancer. In this retrospective cross-sectional study, questionnaires with 147 variables were completed during control appointments. Thirty-eight departments of Oral and Maxillofacial Surgery took part, and 1652 German patients at least 6 months after complete cancer resection answered the questions. Additionally, a physician's questionnaire (N = 1489) was available. Statistical analysis was performed with SPSS vers. 22. Results: The patient's assessment of their appearance and scarring are the most important criteria resulting in wishes for CRS. Furthermore, functional limitations such as eating/swallowing, pain of the facial muscles, numb regions in the operating field, dealing with the social environment, return to work, tumour size and location, removal and reconstruction are closely related. Conclusion: The wish for CRS depends on diverse functional psychosocial and psychological parameters. Hence, it has to be issued during conversation to improve rehabilitation. A decision on the medical treatment can be of greater satisfaction if the surgeon knows the patients' needs and is able to compare them with the medical capabilities. The informed consent between doctor and patient in regard to these findings is necessary.

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.559-565
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• 2003

An analytical method the determination of benzo(a)pyrene (BaP) and its hydroxylated metabolites, 1-hydroxybenzo(a)pyrene (1-OHBaP), 3-hydroxybenzo(a)pyrene (3-OHBaP), benzo(a)pyrene-4,5-dihydrodiol (4,5-diolBaP) and benzo(a)pyrene-7,8-dihydrodiol (7,8-diolBaP), in rat urine and plasma has been developed by HPLC/FLD and GC/MS. The derivatization with alkyl iodide was employed to improve the resolution and the detection of two mono hydroxylated metabolites, 1-OHBaP and 3-OHBaP, in LC and GC. BaP and its four metabolites in spiked urine were successfully separated by gradient elution on reverse phase ODS $C_{18}$ column (4.6 mm I.D., 100 mm length, particle size 5 ㎛) using a binary mixture of MeOH/H₂O (85/15, v/v) as mobile phase after ethylation at 90 ℃ for 10 min. The extraction recoveries of BaP and its metabolites in spiked samples with liquid-liquid extraction, which was better than solid phase extraction, were in the range of 90.3- 101.6% in n-hexane for urine and 95.7-106.3% in acetone for plasma, respectively. The calibration curves has shown good linearity with the correlation coefficients (R²) varying from 0.992 to 1.000 for urine and from 0.996 to 1.000 for plasma, respectively. The detection limits of all analytes were obtained in the range of 0.01-0.1 ng/mL for urine and 0.1-0.4 ng/mL for plasma, respectively. The metabolites of BaP were excreted as mono hydroxy and dihydrodiol forms after intraperitoneal injection of 20 mg/kg of BaP to rats. The total amounts of BaP and four metabolites excreted in dosed rat urine were 3.79 ng over the 0-96 hr period from adminstration and the excretional recovery was less than 0.065% of the injection amounts of BaP. The proposed method was successfully applied to the determination of BaP and its hydroxylated metabolites in rat urine and plasma for the pharmacokinetic studies.