• Sleep Medicine and Psychophysiology
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• v.2 no.2
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• pp.146-155
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• 1995

Jet lag can be defined as the cumulative physiological and psychological effects of rapid air travel across multiple time zone. The consequences of jet lag include fatigue, general malaise, sleep disturbances, and reductions of cognitive and psychomotor performance, all of which have been documented in experimental biological and air crew personnel studies. Thus authors tried to study the jet lag of natural travellers by modified self reporting sleep log. Total 61 healthy travellers was studied for 3 days before and 7 days after jet-flights across seven to ten time zone. The eastbound travelling group was 38 persons, aged 19 -70 and westbound travelling group was 23 persons, aged 13 - 69. Sleep onset time, wake-up time, sleep latency, awakening frequency on night sleep, awakening duration on night sleep, sleepiness at wake-up and nap length were evaluated. Our results suggested that the 7 to 10 time zone shift gave significant influence to traveller's sleep-wake cycles. The date which subjective physical condition was recovered on was $5.16{\pm}1.50$ day after arrivals for eastbound, while for westbound, $4.91{\pm}1.62$ day. In eastbound travelling, sleep onset time became later than baselines and could not recover until 7th day. But in westbound, it became earlier than baseline and could recover until 6th day. The mean score of 24-hour sleepiness was greater in eastboumd than westbound. Therefore the eastbound travelling caused more sleep-wake cycle disturbance and daytime dysfunction than westbound travelling. In other parameters, there was no definite difference between east and westbound. From our results, it was suggested that the symptom severity of jet lag was dependent on the travelling direction. To demonstrate more definite evidence, large sized data collections and comparision by age difference were needed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.855-862
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• 2003

This paper suggests the PIFA structure modified antenna in which short-circuit plate is located between planar element and ground plane, in order to solve the problem of narrow band of existing internal antenna, PIFA. It is also suggested that internal antenna has the perturbation in the patch to broaden the frequency bandwidth. It is possible that the antenna is installed into the mobile telephone with a low profile condition(h=0.015 λ) to use internally, and acquired desired bandwidth(5.2 %) through double resonance structure, remodeling the PIFA that is already well-known as an internal antenna. This paper investigated how characteristic is affected by the feeding point(Yf, Zf), short strip plate(Zs), short strip width(Ws), perturbation width(w), length(d), short plate height(h), dielectric($\varepsilon$$\_$r/) to be slim type antenna. It is compared with existing PIFA bandwidth, and is suggested pattern as the H.E plane. It is simulated using the Microwave Studio of the CST Inc. based on FIM(Finite Integration Method) method and analyzed antenna characteristic following the variation each parameters. The result proved the practical use of PIFA antenna by comparing the measured and simulated data of the antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1269-1275
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• 2003

In this paper, nonradiative dielectric(NRD) rotman lens with a gap-coupled unidirectional dielectric radiator(UDR) has been designed. Gap-coupled UDR is structurally suitable for NRD rotman lens. We have optimized NRD rotman lens for minimizing side-lobe, and calculated design parameters of UDR such as length of resonator and distance of gap using an equivalent circuit model of an evanescent NRD guide. Experimental prototype of UDR is fabricated and measured at the center frequency of 38 GHz. The simulated S-parameter and far-field radiation beam pattern of UDR show good agreements with measured data. Finally, total beam pattern of NRD rotman lens of multi-beam feed has been obtained using a measured pattern of UDR and array factor of NRD rotman lens. The obtained beam pattern shows remarkably suppressed side-lobe.

• Archives of Pharmacal Research
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• v.29 no.1
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• pp.88-95
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• 2006

Analysis of molecular nature of mitochondrial DNA (mtDNA) could be powerful marker for anthropological studies of modern populations. While population genetic studies on mtDNA have been reported for several ethnic groups, no such study has been documented for the Korean population. We surveyed mtDNA polymorphisms in the HVS I of noncoding D-loop region and its upstream region from 430 unrelated healthy Korean population by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing analysis. PCR product with 2,790 bp spanning the specific mtDNA region (mt13715-16504) was subjected to RFLP analysis using 6 restriction enzyme (Hinf I, Hae III, Alu I, Dde I, Mbo I, Rsa I). On the PAUP analysis of PCR-RFLP results, 38 mtDNA haplotypes (Hap 1-38) were detected in the Korean populations, which were classified into 11 haplogroups (Grp 1-11) of related haplotypes encompassing all 38 haplotypes. In comparison of sequencing data with Anderson's reference sequence, the transition type was more prevalent than the transversion type. Insertions or deletions were not found. In addition, three of the polymorphic sites (A16240C, A16351G, G16384A) in HVS-I region are determined newly. The polymorphic sites were distributed randomly in the region, though the frequency at each site was variable. Thus, this research might be required for the genealogical study of Orientals.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.2
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• pp.234-245
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• 2015

This study aimed to investigate factors related to Chinese female marriage immigrants' dietary adaptation. An in-person survey was conducted by a research institute on Chinese female marriage immigrants married to Korean men, having one child or more aged 1~6 years old, and having resided in Korea for at least 1 year before the survey. Data were collected from 309 respondents comprising 151 Han Chinese and 158 Korean-Chinese during the summer of 2013. About two-thirds of respondents were in their 30s and had resided in Korea for 5 to 10 years. Based on the overall mean score for dietary adaptation level (3.50 out of 5 points), the respondents were classified into two groups: low dietary adaptation group (mean score 3.11) and high dietary adaptation group (mean score 3.81). The results of comparative analysis between the two groups showed that the levels of acculturation (p<0.01) and healthy dietary behavior (p<0.01) for the high dietary adaptation group were significantly higher than those of low dietary adaptation group. The number of respondents of the high dietary adaptation group reporting increased food diversity (p<0.01) and decreased frequency of skipping meals (p<0.01) was significantly higher compare to the low dietary adaptation group. Multiple regression analysis was conducted to identify factors related to dietary adaptation. General characteristics, levels of acculturation, and healthy dietary behavior were included as independent variables. As a result, levels of acculturation and healthy dietary behavior as well as education level, monthly household income, and length of residence in Korea were associated with dietary adaptation. In conclusion, Chinese female marriage immigrants showing acculturated and healthy dietary behaviors adapted well to Korean dietary life. The results from this study suggest that diet-related adaptation support programs for Chinese female marriage immigrants may positively affect their acculturation and dietary behaviors.

• Journal of Korean Academy of Nursing
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• v.21 no.3
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• pp.383-395
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• 1991

This study was to investigated the factors influencing the decisions of nurses to resign. The purpose was to contribute information useful for the effective management of nurse staffing resources. The specific objectives were as follows : 1. To investigate the level of job satisfaction of nurses who resign. 2. To analyze the relationship of job expectations and the decisions to resign. 3. To investigate the major reason for nurses' resignations. 4. To identify the relationship of the general characteristics of the nurses and the factors influencing their decisions to resign. 5. To analyze the relationship of the intention to resign and the factors influencing the decisions to resign. The sample consisted of 90 nurses who worked at Y hospital in Seoul from march. 1987 to Feb. 1988 and who had resigned. The instruments used for this study were slavitt et al's Index of Work Satisfaction Scale and a job expectations scale developed by the researcher Analysis of data was done using frequency, t-test and ANOVA. The results of study were as follows : 1. There was no difference in the job satisfaction level of nurses who resigned compared with nurses in active service but the subcategory interaction score was lower and the subcategory salary score was higher than for nurses in active service. 2. Low job expectation scores influenced the decision to resign. 3. The major reason for resigning were personal problems such as marriage, childbirth, and relocation of family. 4. The length of employment and the number of different service areas of the nurses who resigned were associated with the job satisfaction level. 5. The nurses who had have an intention to resign while in active service had lower scores for job satisfaction and the job expectation score was a greater influence on the decision to resign. In conclusion, the factors influencing the decisions of nurse to resign were job satisfaction, job expectations and intention to resign while still in active service.

• Computational Structural Engineering
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• v.10 no.2
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• pp.233-242
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• 1997

The main purpose of this paper is to investigate the dynamic optimal design of continuous beams. The computer-aided optimization technique is used to obtain the near-optimal parameters of continuous beam. The computer program is developed to obtain the natural frequency parameters and the forced vibration responses to a transit point load for the continuous beam with variable support spacing, mass and stiffness. The model test data is in good agreement with the computer calculation, which serves to validate the mathematical analysis. The optimization function to describe the design efficiency is defined as a linear combination of four dimensionless span characteristics; the maximum dynamic stress; the stress difference between span segments; the rms deflection under the transit point load; and the total span mass. Studies of three span beams show that the beam with near-optimal parameters can improve design efficiency when compared to a uniform beam with even spacing of the same total span length.

• The Research Journal of the Costume Culture
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• v.11 no.6
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• pp.889-901
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• 2003

The purpose of this study is to look into the physical features for each residential area by the age, with the female subjects residing in Beijing and Shanghai. This would provide the specific information regarding the body types of Chinese adult women, and additionally it would assist the effective advancement into the Chinese local markets by serving as the basic data for the size development and fitting improvement of clothing products for Chinese women. The body measurements were made with 525 adult female subjects of 20 to 49 years of age, residing in Beijing and Shanghai, China. The number of measurements items was 79. The results are as follows: As they grew older, the women residing in Beijing and Shanghai all showed increases in the items of width, thickness, girth, and length, which are highly correlated with the physical obesity, while they did not show any differences by the age range in the item of height. Differences were also found in the tendency of the type distribution by the age range of Chinese adult women in each residential area. As they grew older, the women residing on Beijing showed increases in the distribution of Body type 2 and Body type 4, which clearly indicated the features of obesity. On the other hand, the women residing in Shanghai showed the almost similar distribution in their 20's and 30's, while those in their 40's showed a high frequency in Body type 2 than in Body type 4.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.626-632
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• 2003

In this paper, forward-wave -3㏈ directional coupler with finite-thickness conductor and asymmetrical coupled lines are designed and experimentally verified using mode-matching based design methodology. Most of studies published in the literatures about the coupled lines are mainly concentrated on the adjustment of coupling amount by changing various geometric configurations. The analysis results in this paper show that thicker metalization requires reduced coupler length in the forward-wave directional coupler composed of asymmetrical coupled lines. Several forward-wave directional -3 ㏈ couplers with finite metalization thickness composed of asymmetrical coupled microstrip lines have been designed in the 5 ㎓ based on proposed design method. The measured data show -4.05㏈∼-4.09㏈ coupling at center frequency which is very closed to design value. The tight coupling has been implemented with accurate design methodology which take mentalization thickness into account.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.330-336
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• 2004

In this work, in order to obtain the detailed information about lightning electromagnetic pulses, the electric fields radiated from multiple lightning return strokes were measured and analyzed statistically. The electric field measuring system consists of a hemisphere antenna of 30cm in diameter, integrator and data acquisition device, and its frequency bandwidth ranges from 200Hz to 1.56MHz, and the sensitivity is 0.96㎷/V/m. The electric field signals are digitized every 200ns with the transient signal analyzer having the resolution of 12-bit and the recording length of 5 kilowords and are registered at personal computer. As a result, the electric fields produced by the first return stroke begin with a slow initial part or front, which starts just after or during the last stepped leader. On the average the rise times of the electric fields for the positive first, second and third strokes are 4.21${\mu}\textrm{s}$, 3.94${\mu}\textrm{s}$ and 2.75${\mu}\textrm{s}$, respectively, and those for the negative first, second and third strokes are 3.46${\mu}\textrm{s}$, 3.15${\mu}\textrm{s}$ and 2.79${\mu}\textrm{s}$, respectively. The zero-crossing times of the electric fields for first return strokes range from about 10 to 80${\mu}\textrm{s}$. The mean zero-crossing times for subsequent return strokes are shorter than those for first lightning return strokes.