• 터널과지하공간
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• 제17권2호
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• pp.83-89
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• 2007

충격반향기법은 특정 매질에 충격을 가하여 매질의 동적 불성을 측정할 수 있는 비파괴 시험법이다. 본 연구에서는 암석시편에 충격반향기법을 수행할 수 있는 시험장비를 설치하고, 동적 물성치를 측정할 수 있는 시스템을 구축하였다. 이를 통해 국내 5개 지역에서 채취한 암석 시료 및 시멘트 모르타르와 알루미늄 합금에 대해 시험을 수행하여 동적 물성치를 측정하고, 1회의 충격시험으로 종파 및 횡파의 공진주파수와 감쇠비를 결정하였다. 그 결과. 동탄성계수와 정탄성계수는 10%내외의 차이를 가진 결과치가 도출되었고, 동포아송비는 정포아송비에 비해 0.07 이상 높은 값이 측정되었다. 또한 풍화도가 높거나 절리가 발달한 암석일수록 감쇠비가 증가하는 현상을 관찰하였다.

• 동의생리병리학회지
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• 제21권3호
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• pp.748-754
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• 2007

Electroacupuncture is the combined treatment of mechanical and electric stimuli on the needle head, on which electricity runs after acupuncturing at the acupuncture points. It is reported that its treatment effect depends on the parameter of stimulus, which is wave of stimulus, frequency, voltage, and duration of electric current. To get the effective treatment, stimulus intensity over threshold is needed. We planned to experiment whether acupuncture effect is affected by sex, age, and weight. After we conducted electric stimulus at Zusanli(ST 36) which is known to increase small intestinal motility in normal rats, we observed the effects and got the following results. Though the increased effects of small intestinal motility of electro-acupuncture at Zusanli(ST 36) did not show the difference of sex, this effect was observed to have a tendency to decrease according to weight increase without distinction of sex. But the effect of electro-acupuncture shown in 4, 5, 7 weeks old without distinction of sex was observed to have a tendency to decrease with the growing of weeks-old in the male rat group. And the significant change without specific tendency was observed in the 4, 5 weeks old female rat group. This result suggested that sex, weight, and age should be considered to get the efficient electro-acupuncture. The more experimental study should be advanced to investigate the correlation between the factors that can affect the acupuncture treatment, and, afterward, the interconnection into the clinical use.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.723-726
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• 2005

The two major obstacles in the application of IPMC to flapping actuators operated in the air are solvent loss and actuation force. In this paper, solvent loss of various IPMCs made of Nafion$^{TM}$117(183$\mu$m thickness) has been experimentally investigated to find out the best combination of cation and solvent for minimal solvent loss in IPMCs and higher actuation force. For this purpose. experiments for the internal solvent loss measurement of IMPCs have been conducted for various combinations of cation and solvent. From the experiments, it was found that heavy water showed improvement in the operating time up to more than two minutes. in the tip force measurement of IPMCs, it was found that smaller and thicker IPMCs produced larger tip forces. However, the shorter IPMCs generated reduced actuation displacements and created flapping motion with decreased natural frequency. For the design of flapping device actuated by 5mm wide, 10mm long, 0.2mm thick IPMCs were used in the stacked form. Since the actuation force is a few gram-force, we stacked five IPMCs to improve actuation force. To amply the actuation force, rack-and-pin ion type hinge was used for the flapping device and insect (Cicadidae) wing was attached to the stacked IPMC actuator. In the flapping test, the device could generate flapping angle of 15$^{\circ}$ at 6Hz excitation by 2.5 voltage square wave input.

• Nutrition Research and Practice
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• 제9권5호
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• pp.496-502
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• 2015

BACKGROUND/OBJECTIVES: This study was performed to investigate the association between the dietary intake of fish and shellfish, and omega-3 polyunsaturated fatty acids (PUFAs) and cardiovascular disease (CVD) risk factors in the middle-aged Korean female patients with Type 2 diabetes (T2D). SUBJECTS/METHODS: A cross-sectional analysis was performed with 356 female patients (means age: 55.5 years), who were recruited from the Huh's Diabetes Clinic in Seoul, Korea between 2005 and 2011. The dietary intake was assessed by a validated semi-quantitative food frequency questionnaire and analyzed using the Computer Aided Nutritional Analysis program (CAN-Pro) version 4.0 software. RESULTS: In a multiple regression analysis after the adjustment for confounding factors such as age, BMI, duration of diagnosed T2D, alcohol consumption, fiber intake, sodium intake, and total energy intake, fish and shellfish intake of the subjects was negatively associated with triglyceride and pulse wave velocity (PWV). Omega-3 PUFAs intake was negatively associated with triglyceride, systolic blood pressures, diastolic blood pressures, and PWV. The multiple logistic regression analysis with the covariates showed a significant inverse relationship between the omega-3 PUFAs consumption and prevalence of hypertriglyceridemia [OR (95% CI) for greater than the median compared to less than the median: 0.395 (0.207-0.753)]. CONCLUSIONS: These results suggest that the consumption of fish and shellfish, good sources of omega-3 PUFAs, may reduce the risk factors for CVD in the middle-aged female patients with T2D.

• 한국해양공학회지
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• 제27권5호
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• pp.63-69
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• 2013

The mooring lines of a floating type offshore plant are known to show wide banded and bimodal responses. These phenomena come from a combination of low and high frequency random load components, which are derived from the drift-restoring motion characteristic and wind- sea, respectively. In this study, fatigue models were applied to predict the fatigue damage of mooring lines under those loads, and the result were compared. For this purpose, seven different fatigue damage prediction models were reviewed, including mathematical formula. A FPSO (floating, production, storage, and offloading) with a $4{\times}4$ spread catenary mooring system was selected as a numerical model, which was already installed at an offshore area of West Africa. Four load cases with different combinations of wave and wind spectra were considered, and the fatigue damage to each mooring line was estimated. The rain flow fatigue damage for the time process of the mooring tension response was compared with the results estimated by all the fatigue damage prediction models. The results showed that both Benasciutti-Tovo and JB models could most accurately predict wide banded bimodal fatigue damage to a mooring system.

• 한국ITS학회 논문지
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• 제14권1호
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• pp.1-12
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• 2015

매설형 검지기는 검지 성능이 타 검지기에 비해 우수하지만, 설치 및 관리비용이 클 뿐 아니라 도로의 재포장이나 도로파손으로 인해 수명이 짧다는 단점이 있다. 이에 반해 기존 지주에 부착하여 사용하는 검지시스템인 비매설형검지기는 도로 노면을 손상시키지 않기 때문에 설치가 쉽고, 유지관리비용이 적다는 장점이 있다. 비매설식 검지기는 이러한 장점에도 불구하고, 검지 성능이 낮아 아직까지 신호제어용으로 사용하지 못하는 실정이다. 본 연구에서는 비매설형검지기 중에 정확도가 가장 높은 FMCW 방식의 레이더에 대해 성능평가를 수행하고, 신호제어용 검지용도별로 현장적용 유/무 결과를 제시하였다.

• 한국정보통신학회논문지
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• 제11권4호
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• pp.808-814
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• 2007

본 논문에서 제안하는 크레인의 이동거리 측정시스템은 전파의 위상 및 크기를 이용하여 거리를 인식하는 기술이다. 제안하는 기술은 거리측정용 무선송수신기를 설계하고, 측정시스템을 구현하며, 송수신된 900Mhz대 RF 신호로부터 중간주파수인 450Khz의 아날로그 데이터를 디스크에 저장한다. RF 측정결과 9.3 dBm의 출력과 96dBc@10khz의 위상 잡음특성을 얻었고 얻어진 RF 신호에 대한 450Khz 데이터를 디지털신호처리를 통하여 거리정보를 얻는 것이다. 측정된 거리의 평가를 위해서 실제거리와 측정된 거리를 비교분석하고, 또한 평균처리 및 진폭특성을 통한 측정오차 제거 방법을 제시하였다. 최종거리 측정 결과 Ref. 신호에 비하여 10m-30m 거리에 대하여 0.12, 그리고 5m 이내의 근거리 실험에서 위상오차가 0.00422이었으나, 진폭특성을 보완하여 4m에서 2.4E-04의 오차를 얻을 수 있었다.

• 한국정보통신학회논문지
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• 제12권1호
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• pp.25-32
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• 2008

본 논문에서는 초고속 광대역 서비스를 제공하기에 적합한 주파수 대역인 60GHz 밀리미터파대역의 전파특성을 파악하기 위하여 직접 파를 제외한 반사파 및 투과파에 대한 신호세기를 측정하여 평균 전력 및 표준 편차를 분석하였다. 먼저, 장애물 투과에 의한 수신 신호 세기를 분석 한 결과, 철문, 동판 등은 약 40dB이상의 투과 손실치를 나타내어 투과가 거의 발생하지 않았으며, 고무, 스티로폼 및 유리등이 약 3dB의 투과 손실치로 가장 적게 나타났다. 입사각이 60도 인 경우 장애물에 의한 반사파 수신신호세기는 파티션에서의 손실치가 약 22dB로서 크게 나타났으며, 벽면 반사 손실치가 약 6dB로 가장 적게 나타났다. 이상의 결과는 반사파와 투과파가 서비스 영역 결정에 영향을 미치는 WPAN과 같은 피코셀 이동통신망의 설계에 이용될 수 있을 것으로 판단된다.

• Wind and Structures
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• 제18권4호
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• pp.423-441
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• 2014

The high frequency base balance (HFBB) technique is a convenient and relatively fast wind tunnel testing technique for predicting wind-induced forces for tall building design. While modern tall building design has seen a number architecturally remarkable buildings constructed recently, the characteristics of those buildings are significantly different to those that were common when the HFBB technique was originally developed. In particular, the prediction of generalized forces for buildings with 3-dimensional mode shapes has a number of inherent uncertainties and challenges that need to be overcome to accurately predict building loads and responses. As an alternative to the more conventional application of general mode shape correction factors, an analysis methodology, referred to as the linear-mode-shape (LMS) method, has been recently developed to allow better estimates of the generalized forces by establishing a new set of centers at which the translational mode shapes are linear. The LMS method was initially evaluated and compared with the methods using mode shape correction factors for a rectangular building, which was wind tunnel tested in isolation in an open terrain for five incident wind angles at $22.5^{\circ}$ increments from $0^{\circ}$ to $90^{\circ}$. The results demonstrated that the LMS method provides more accurate predictions of the wind-induced loads and building responses than the application of mode shape correction factors. The LMS method was subsequently applied to a tall building project in Hong Kong. The building considered in the current study is located in a heavily developed business district and surrounded by tall buildings and mixed terrain. The HFBB results validated the versatility of the LMS method for the structural design of an actual tall building subjected to the varied wind characteristics caused by the surroundings. In comparison, the application of mode shape correction factors in the HFBB analysis did not directly take into account the influence of the site specific characteristics on the actual wind loads, hence their estimates of the building responses have a higher variability.

• 지구물리와물리탐사
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• 제13권2호
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• pp.144-152
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• 2010

제주도 화산암 두께변화를 연구하기 위하여, 단주기와 광대역 지진계를 각각 8개와 4개 조사지 지표에 설치하여 상시미동 자료를 30 ~ 60분 동안 100 Hz 샘플률로 기록하였다. 인공잡음은 주간자료의 1.8 Hz 이상에서 나타나는 반면, 자연잡음은 0.4 ~ 0.8 Hz 범위에서 주간 및 야간 기록자료 모두에 기록되어 나타난다. H/V 스펙트럼비를 이용하여 구한 우세주파수는 0.2 ~ 0.7 Hz 범위에 분포한다. 우세주파수는 한라산 중심부로 갈수록 점진적으로 작은 값을 보여, 기존의 중력 및 자력모델의 결과처럼 제주도의 기반암이 섬 중심부 아래로 휜 구조임을 반영한다. 기반암 상부 현무암의 평균 횡파속도를 1,800 m/s로 가정할 경우, 각 조사지의 기반암 깊이는 약 640 ~ 2,140 m 정도로 평가된다.