• 해양환경안전학회지
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• 제19권6호
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• pp.666-673
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• 2013

본 연구는 빠른 운항 속도와 짧은 운용 시간을 요구하는 임무에 활용될 저가 소형 자율 무인잠수정에 고가 대형 관성 측정 장치를 대신하여 사용할 수 있는 저가 소형 자세 측정 장치 개발 및 성능 검증을 수행하였다. 저가 소형 자세 측정 장치 개발을 위해서 MEMS 기술을 적용한 gyro, accelerometer 및 magnetometer 채택하여 MEMS 기반 하드웨어를 제작하였으며, 좌표 변환 공식과 칼만 필터를 적용하여 자세 계산 알고리즘을 구현하였다. 또한 개발된 MEMS 기반 자세 측정 장치에 대한 기본 성능 검증을 위한 지자기센서 검증 시험, 정적 자세 시험, 차량 시험, 운동 모사 장치 시험을 수행하였으며, 각각 시험 결과를 제시하였다. 지자기센서 검증 시험 결과 외부 자기장 보정을 통하면 개발된 MEMS 기반 자세 측정 장치의 측정 결과가 외부 자기장에 강인함을 확인하였으며, 정적 자세 시험 및 차량 시험을 통하여 자세 변화가 크지 않는 환경에서 자세 측정 오차가 $0.5^{\circ}/hr$ 임을 확인하였다. 운동 모사 장치 시험을 통하여 5분 내외 자세 변화가 큰 운동 중에도 자세 측정 오차가 발산하지 않고 $1^{\circ}/hr$ 이내임을 확인하였다. 상기 시험 결과로부터 개발된 MEMS 기반 자세 측정 장치가 목표 성능인 $1^{\circ}/hr$이내 roll, pitch, yaw 오차를 보여주고 있음 확인하였으며, 이로부터 20분 내외 운용 시간 동안 정확한 자세 정보 제공 가능성을 확인할 수 있었다.

• 한국콘텐츠학회논문지
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• 제16권3호
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• pp.219-231
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• 2016

신장의 기능을 정량분석 할 수 있는 $^{99m}Tc$-DMSA 평면 영상은 단층영상에 비해 병소의 위치 정보에 한계가 있다. 따라서 광자 신호에 민감한 범용성 collimator로 교체하여 SPECT 방식으로 임상실험을 시행한 후, 진단의 정확도와 검사 소요시간을 분석하여 임상적용 가능성을 평가하였다. 10명의 실험대상에게 방사성의약품(1.0-1.2 MBq/kg)을 정맥주사하고, 이중 검출기 감마카메라를 이용하여 planar scan (high resolution (HR)-mode, $256{\times}256$, 50 kcts/view, 4 image)과 SPECT (HR / high sensitive (HS)-mode, $128{\times}128$, step and shoot, $180^{\circ}$, variable sec/angle, total 64 frame, OSEM reconstruction)를 시행하였다. 획득한 데이터를 분석 프로그램을 이용하여 비교한 결과, 실험 방법에 따라서 total counts는 high sensitive-mode SPECT가 대략 1.8-5.6 배 정도 많았고, counts를 이용한 상대신장기능은 모든 실험에서 유의한 수준 범위에서 차이가 없었으며(p=0.96), 검사 소요시간은 39%정도 단축되었다. 그러므로 고감도 범용성 collimator를 이용한 $^{99m}Tc$-DMSA renal SPECT는 planar scan에 비하여 신장의 기능을 정량분석 할 수 있고, 병변의 위치에 대한 정보를 보다 정확하게 진단할 수 있으며, 동시에 검사 소요시간을 단축시킬 수 있으므로 임상적으로 유용하게 활용할 수 있을 것으로 사료된다.

• Journal of Korean Biological Nursing Science
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• 제11권1호
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• pp.68-76
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• 2009

Purpose: The purpose of this study was to evaluate the hemodynamic changes in degree and duration that occur during Valsalva maneuver (VM). Furthermore, we wanted to investigate the patterns and mechanisms of physiological hemodynamic control. Method: Thirty six healthy college students were recruited from Y university. Each participant was provided with written informed consent. Blood pressure (BP), heart rate (HR), cardiac output (CO) were continuously recorded using the Finometer. Result: During the phase I of VM, means of systolic and diastolic pressures were increased by 32.15% and 38.28%, respectively, compared with basal values. HR and CO were decreased by 9.91% and 13.01%, respectively. Immediately after the maneuver (phase III), systolic and diastolic pressures were decreased by 5.05% and 6.24%, respectively, compared with those obtained in the phase II. HR and CO were elevated by 13.33% and 11.93%, respectively, compared to the levels of earlier phases. BPs were represented with overshoot in the phase IV, and recovered by baseline values about 20 sec after VM. Conclusion: These results demonstrated that hemodynamic changes are variable in the event of VM even in healthy humans. It will be valuable to accumulate more quantitative hemodynamic information in special populations such as the elderly and the patients with cardiovascular problems.

• 천문학회보
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• 제42권2호
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• pp.49.3-50
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• 2017

There have been recent studies which revealed a tendency that thermal inertia decreases with the size of asteroidal bodies, and suggestions that thermal inertias of cometary bodies should be much smaller than those asteroidal counterparts, regardless of comets' nuclear sizes, which hints a way to differentiate cometary candidates from asteroids using thermal inertia information. We thus selected two comet-like objects from AKARI satellite of JAXA, namely, 107P/ (4015) Wilson-Harrington and P/2006 HR30 (Siding Spring), and applied simple thermophysical model to test the idea. Both targets did not show any comet-like activity during the observations. From the model, we found Wilson-Harrington to have size of 3.7-4.4 km, geometric albedo 0.040-0.055 and thermal inertia of 100-250 J m-2 K-1 s-0.5, which coincide with previous works, and HR30 to have size of 24-27 km, geomoetric albedo of 0.035-0.045 with thermal inertia of 250-1000 J m-2 K-1 s-0.5. HR30 is found to have the rotation pole near the ecliptic plane (the latitude between -20 and +60 deg). Based on the results, we conjecture that comet-like objects are not clearly distinguishable from asteroidal counterpart using thermal inertia.

• Journal of Mechanical Science and Technology
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• 제18권3호
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• pp.388-394
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• 2004

Composites of Si$_3$N$_4$-SiC containing up to 30 wt% of dispersed SiC particles were fabricated via hot-pressing with an oxynitride glass. To determine the effect of sintering time and SiC content on the mechanical properties and the cutting performance, the composites with fixed 8hr-sintering time and 20 wt% SiC content were fabricated and tested. Fracture toughness of the composites increased with increasing sintering time, while the hardness increased as the SiC content increased up to 20 wt%. The hardness of the composites was relatively independent of the grain size and the sintered density. For machining heat-treated AISI4140, the insert with 20 wt% SiC sintered for 8hr showed the longest tool life while the insert with 20 wt% SiC sintered for 12hr showed the longest tool life for machining gray cast iron. An effort was made to relate the mechanical properties, such as hardness, fracture toughness and wear resistance coefficient with the tool life. However, no apparent relationship was found between them. It may be stated that tool life is affected by not only the mechanical properties but also other properties such as surface roughness, density, grian size and the number of the inherent defects in the inserts.

• 인터넷정보학회논문지
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• 제10권4호
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• pp.213-222
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• 2009

IEEE 802.15.3 HR-PAN은 PHY와 MAC으로 구성되어 있다. 그 중 MAC 기술은 부족한 채널 자원을 관리하는 중요한 역할을 한다. 기존 IEEE 802.15.3의 MAC 프로토콜에서 각 DEV에게 채널을 할당하는 방법은 네트워크의 상태나 주위 환경과 무관하게 고정된 형태이다. 이 논문에서 제안한 Hybrid MAC 프로토콜은 IEEE 802.15.3 HR-WPAN 환경에서 네트워크의 상태에 따라 TDMA 방식과 CSMA 방식을 유동적으로 사용할 수 있게 된다. 이 논문에서는 TDMA의 장점인 충돌 없는 전송시간의 보장과 CSMA의 장점인 높은 채널 사용률을 결합하여 802.15.3의 standard MAC보다 보다 높은 전송률을 보이는 Hybrid MAC을 제안한다.

• 보건행정학회지
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• 제29권1호
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• pp.68-76
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• 2019

Background: This study investigates the association between sleep duration and diabetes mellitus (DM) in a large representative population-based survey in South Korea. Methods: The fourth (2007-2009), fifth (2010-2012), and sixth (2013) Korea National Health and Nutrition Examination Survey data sets were used. A total of 37,989 individuals were selected for the study. Chi-square tests and multivariate logistic regression analyses were used to analyze whether general characteristics, health status, and health risk behaviors were associated with DM. Results: After adjusting for confounders, the odds of DM in short sleepers (${\leq}5hr/day$) and long sleepers (${\geq}9hr/day$) were 1.033-times higher (95% confidence interval [CI], 0.913-1.169) and 1.334-times higher (95% CI, 1.140-1.562), respectively, compared with individuals who slept 7 hr/day. Subgroup analysis according to gender showed a U-shaped association for both genders, although it appeared stronger in men. Conclusion: This study identified a U-shaped association between sleep duration and the risk for DM. Additional studies should help clarify the important information in this study.

• Journal of Nutrition and Health
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• 제29권5호
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• pp.507-516
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• 1996

This study was undertaken to estimate seasonal variation of riboflavin status and investigate the relationship between riboflavin intake and its biochemical status in rural women. Dietary intake was measured by determining both 24hr recall method and conventient method. The riboflavin intake was also estimated by food frequency method. Ribofiavin biochemeical status was assessed by erythrocyte glutathione reductase activity coefficient(EGR AC) and urinary riboflavin excretion. All information was repeatly collected in three seasons ; farming season (June), harvest season(October), nonfarming season(February). Mean daily riboflavin intake was below RDA for Koreans in all seasons. Cereal & pulse, vegetable were the primary sources of riboflavin intake and provided above 60% of the total dietary riboflavin intake in all seasons. Riboflavin biochemical status was significantly different among seasons(EGR AC P<0.005, 24hr urinary riboflavin excretion P<0.05), and riboflavin biochemical deficiency was highest in February. The mean values of EGR AC revealed riboflavin deficiency in all seasons. However the mean values of urinary riboflavin excretion were within the normal range except 24hr urinary riboflavin excretion in February. On the basis of EGR AC criteria, 44.7% of subjects were at risk of deficiency in June, 44.7% in October, 81.6% in February. Result of individual riboflavin status assessed by EGR AC or 24hr urinary riboflavin excretion criteria was quite alike. Urinary riboflavin excretion per gram of creatinine underestimated riboflavin deficiency. Significant correlations were observed among biochemical indexes. It also appeared that riboflavin intake measured by food frequency method showed significant correlation with biochemical indexes, especially high correlation with EGR AC (P<0.001). The results indicated that the prevalence of riboflavin deficiency seems to be high among rural women in all seasons and the inadequacy of dietary riboflavin intake was reflected in the abnormalcy of riboflavin biochemical status assessed by EGR, AC. Therefore EGR AC seems to be more sensitive measure of impaired riboflavin status compared to urinary excretion.

• Journal of Nutrition and Health
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• 제38권5호
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• pp.335-343
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• 2005

쥐에게 콩과 콩나물, 순수한 genistein을 함유되어 있는 genistein함량을 기준으로 동일하게 급여 (20mg/kg) 시켰을 때, 체내에서 흡수가 되는 속도는 soy, soy sprout, pure genistein군의 순이며 일반소화율은 soy sprout, pure genistein, soy군의 순이었다. 이로써 soy의 genistein은 쉽게 흡수되고 배설되며, 또한 전혀 흡수되지 않고 배설분으로 나오는 양도 세 그룹 중 가장 많은 것을 알 수 있었다. 이는 담즙 등으로 재순환되지 않는 양이 다른 그룹보다 많기 때문이라고 추정되었다. 따라서 생리기능상의 목적으로 isoflavone을 섭취하고자 할 때에는 콩보다는 콩나물형태로의 섭취가 타당할 것으로 생각되며 정확한 결과를 위해서도 사람이 섭식하는 상태의 콩과 콩나물의 isoflvones의 흡수율을 조사할 필요성이 있을 것으로 생각되었다.

• Journal of Nutrition and Health
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• 제36권7호
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• pp.769-776
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• 2003

This study has analyzed the association of physical activity and television watching time with obesity in 30-50 aged women from middle income town in Busan city area. Data were obtained using a questionnaire, including information about physical activity, TV watching time and health habit; social data regarding educational level and monthly income; family history of chronic condition. Height and weight were measured. Outcome variable was obesity, defined as a body mass index 25 kg/m$^2$ or greater. Odds ratios (OR) for obesity were estimated by multivariate logistic regression, and interpreted as a relative risk of obesity. The prevalence of obesity was 11.8%. The mean BMI of obese women was 26.9 kg/m$^2$. The OR of obesity was higher in subject of 40s than 30s. Subjects who had higher educational level presented lower OR than those of elementary or middle school education. Family income was not associated with obesity. Women having a family history of chronic condition had higher risk of obesity than those who did not have it. The OR was lower in active people at work (OR = 0.51; 95% CI = 0.26 - 0.98) than in inactive ones, and the ORs associated with regular exercise or activity at leisure time were not statistically different. However, subjects watching TV $\geq$ 3.5 hr/day showed higher OR (OR = 2.34; 95% CI = 1.16 - 4.74), compared with those watching TV $\geq$ 1.5 hr/day. Association of the joint classification of physical activity variables with obesity was estimated. The highest relative risk of 5.99 was in women in physically inactive at work and high category of TV watching ($\geq$ 3.5 hr/day). Even in women in active at work, the watching TV $\geq$ 3.5 hr/day made them have the high OR (OR = 2.44; 95% CI = 1.03 - 5.77). And at each time level of TV watching, the increasing activity level at work was associated with lower OR for obesity. These findings suggest that both TV watching time and physical activity at work were related to obesity in adult female, each with independent effects on obesity. TV watching time seems to be a significant factor that could partly evaluate the energy expenditure.