• 대한치과보철학회지
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• 제43권2호
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• pp.248-257
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• 2005

Statement of problem. Cortical bone plays an important role in the primary implant stability, which is essential to immediate/early loading. However, immediate load-bearing capacity and primary implant stability according to the change of the cortical bone thickness have not been reported. Purpose. The objectives of this study were (1) to measure the immediate load-bearing capacity of implant and primary implant stability according to the change of cortical bone thickness, and (2) to evaluate the correlation between them. Material and methods.48, screw-shaped implants (3.75 mm$\times$7 mm) were placed into bovine rib bone blocks with different upper cortical bone thickness (0-2.5 mm) and resonance frequency (RF) values were measured subsequently. After fastening of healing abutment. implants were subjected to a compressive load until tolerated micromotion threshold known for the osseointegration and load values at threshold were recorded. Thereafter, RF measurement after loading, CT taking and image analysis were performed serially to evaluate the cortical bone quality and quantity. Immediate load-bearing capacity and RF values were analyzed statistically with ANOVA and post-hoc method at 95% confidence level (P<0.05). Regression analysis and correlation test were also performed. Results. Existence and increase of cortical bone thickness increased the immediate load-bearing capacity and RF value (P<0.05) With the result of regression analysis, all parameter's of cortical bone thickness to immediate load-bearing capacity and resonance frequency showed significant positive values (P<0.0001). A significant high correlation was observed between the cortical bone thickness and immediate load-beating capacity (r=0.706, P<0.0001), between the cortical bone thickness and resonance frequency (r=0.753, P<0.0001) and between the immediate load-bearing capacity and resonance frequency (r=0.755, P<0.0001). Conclusion. In summary, cortical bone thickness change affected the immediate load-baring capacity and the RF value. Although RF analysis (RFA) is based on the measurement of implant/bone interfacial stiffness, when the implant is inserted stably, RFA is also considered to reflect implant/bone interfacial strength of immediately after placement from high correlation with the immediate load-baring capacity. RFA and measuring the cortical bone thickness with X-ray before and during surgery could be an effective diagnosis tool for the success of immediate loading of implant.

• 한국군사과학기술학회지
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• 제20권2호
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• pp.187-196
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• 2017

The size of raw data has dramatically increased due to the recent trend of Synthetic Aperture Radar(SAR) development plans for high resolution and high definition image acquisition. The large raw data has an impact on satellite operability due to the limitations of storage and transmission capacity. To improve the SAR operability, the SAR raw data shall be compressed before transmission to the ground station. The Block Adaptive Quantization (BAQ) algorithm is one of the data compression algorithm and has been used for a long time in the spaceborne SAR system. In this paper, an optimization method of BAQ threshold table is introduced using real SAR raw data to prevent the degradation of signal quality caused by data compression. In this manner, a new variation estimation strategy and a new threshold method for block type decision are introduced.

• ETRI Journal
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• 제40권3호
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• pp.291-302
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• 2018

The deployment of an incremental hybrid decode-amplify and forward relaying scheme is a promising and superior solution for cellular networks to meet ever-growing network traffic demands. However, the selection of a suitable relaying protocol based on the signal-to-noise ratio threshold is important in realizing an improved quality of service. In this paper, an incremental hybrid relaying protocol is proposed using polar codes. The proposed protocol achieves a better performance than existing turbo codes in terms of capacity. Simulation results show that the polar codes through an incremental hybrid decode-amplify-and-forward relay can provide a 38% gain when ${\gamma}_{th(1)}$ and ${\gamma}_{th(2)}$ are optimal. Further, the channel capacity is improved to 17.5 b/s/Hz and 23 b/s/Hz for $2{\times}2$ MIMO and $4{\times}4$ MIMO systems, respectively. Monte Carlo simulations are carried out to achieve the optimal solution.

• 한국전자파학회논문지
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• 제23권5호
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• pp.632-639
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• 2012

Ad-hoc 네트워크는 음영 지역, 재난 지역, 전쟁 시와 같은 통신 인프라가 구축되기 어려운 상황에서 유용하게 사용될 수 있다. 그러나 음성 및 데이터 서비스 등과 같은 무선 서비스의 제공을 위해 많은 양의 네트워크 용량이 필요하게 되지만, 기존의 제한된 주파수 자원에 따른 주파수 부족 상황 및 주파수 자원 정책의 규제에 따라 원활한 주파수 사용이 어려운 상황이다. 이에 따라 높은 주파수 활용을 제공하는 인지 무선 시스템을 ad-hoc 네트워크에 적용하여 보다 다양하고 확장된 네트워크 서비스를 제공할 수 있다. 하지만 기존 스펙트럼 센싱에 있어 임계치가 정적으로 작용하므로 detection probability가 낮게 검출되는 단점이 있다. 이러한 점을 보완하여 신호들의 detection probability를 향상시키기 위해 adaptive threshold를 이용할 것이다. 본 논문에서는 동적인 임계치를 이용하여 수신 신호의 power에 따라 임계치가 변화하여 신호들의 detection probability를 향상시키는 센싱 성능을 보여 준다.

• 콘크리트학회논문집
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• 제17권3호
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• pp.481-485
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• 2005

The present study examines the distribution of calcium hydroxide, unhydrated cement grain and porosity at the steel-concrete interface. The formation of calcium hydroxide has been confirmed by microscopic analysis using BSE images containing the ITZ between the steel and concrete. It was found that calcium hydroxide does not form a layer on the steel surface, different from the hypothesis that has been available in investigating the corrosion of steel in concrete, ranging from 5 to $10\%$ within the steel surface. Moreover, the high level of porosity at the ITZ was observed, accounting for $30\%$, which may reduce the buffering capacity of cement hydration products against a local fall in the pH. These findings may imply that the mole of ($Cl^-$) :($OH^-$) in pore solution as chloride threshold level lead to wrong judgement or to a wide range of values.

• 한국지진공학회논문집
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• 제25권6호
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• pp.251-259
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• 2021

Current seismic fragility functions for buildings were developed by defining damage state threshold based on story drift concerning foreign references and using the capacity spectrum method based on spectral displacement. In this study, insufficient details and dependence on the core location of piloti-type buildings were not reflected in the fragility function because it was developed before the Pohang earthquake. In order to develop an improved one for piloti-type buildings, several types of core were selected, damage state threshold was determined based on the capacity of structural members, and three-dimensional analyses were utilized. As a result, seismic fragility functions based on spectral acceleration were developed for various core locations and different shear strengths of the column stirrup. The fragility of piloti-type buildings significantly varied according to core location, an additional single wall, and whether the contribution of column stirrup was included or not. To estimate fragility more reasonably, it is necessary to prepare the parameters to reflect actual state well.

• 대한물리치료과학회지
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• 제27권3호
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• pp.1-11
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• 2020

Background: The purpose of this study was to investigated the effects of threshold resistance inspiratory muscle training on respiratory function in chronic stroke patients. Design: Randomized Controlled Trial Methods: Eighteen patient with stroke were randomly assigned to the experimental group (n=9) and control group (n=9) all testing and training. The experimental group underwent threshold resistance inspiratory muscle training with resistance adjusted of maximal inspiratory pressure, 60 breathing a day and general physical therapy 30 minutes a day, 5 times a week for 4 weeks. The control group was taken general respiratory muscle training and general physical therapy for 4 weeks in the same way. Respiratory function, walking ability were evaluated before and after the intervention. Statistical significance of the results were evaluated by ANCOVA between control group and experimental group after intervention. Results: There was a significant increase in FVC and FEV1 in the experimental group in pulmonary function tests (p<0.05). There was a significant difference with the maximum inspiratory pressure and the maximum inspiratory flow rate between experimental and control group (p<0.05). There was no significant difference with the maximum inspiratory capacity between experimental and control group (p>0.05) but the maximum inspiratory capacity of experimental group some increased than that of control group. Conclusion: These finding gave some indications that the threshold resistance inspiratory training may benefit on pulmonary function in people with stroke, and it is feasible to be included in rehabilitation interventions with this population.

• 한국임상보건과학회지
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• 제3권2호
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• pp.340-353
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• 2015

Purpose. This study of purpose was to to compare of Aerobic and Anaerobic Capacity between Sasang Constitutions and ACE Gene Polymorphism. Methods. 24 healthy males were participated in this experiment who were in their twenties and had no disease, then they were divided by ACE type and by Sasang constitutions with QSCC II. According to these group, the body compositon, Aerobic capacity including VO2max, Anaerobic Capacity were measured. Results. In this study, According to ACE type, ID type were 8, II were 8 and DD type were 8 persons. According to ACE type, there were significant difference among type, especially, II, ID type more than DD. II type is more higher than any type and DD type is lower in the ratio of Blood Lactic recovery. DD type was more excellent than other type in Anaerobic power. According to Sasang Constitutions, there were 8 SoYang, 5 Taeum, 11 Soeum and then no TaeYang constitution. In Aerobic capacity, Taeum constitution had significantly high means and Anaerobic threshold. In the ratio of Blood lactic recovery, Taeum constitution was excellent and SoYang had poor recovery capacity. SoYang had more excellent than other constitution significantly in Anaerobic capacity. Comparing ACE type with Sasang constitution, Soyang constitution included 4 ID types, Taeum inclued 2 II types and 2 ID types then Soeum included 6 DD types. Compared of Aerobic and Anaerobic capacity between Sasang constitutions and ACE type, Soyang constitutions were similar to ID type, Taeum similar to II type and ID type and then Soeum were DD type. Conclusions. This study had made it clear that there were similar feature between ACE type and Sasang constitutions. Also it's possible to predict the Aerobic capacity that may be foreseen by ACE type with Sasang questionnaire method but not Anaerobic capacity.

• 대한전자공학회논문지TC
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• 제42권12호
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• pp.1-8
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• 2005

본 논문에서는 방송, 통신, 인터넷이 하나가 되는 BcN 환경에서 멀티캐스트 서비스를 위한 연결 수락 제어(Call Admission Control) 방안에 대하여 알아본다. 제한된 시스템의 처리 용량으로 인해 서비스 요청에 대하여 적절하게 연결 수락을 제어함으로써 QoS를 효과적으로 지원하는 것이 필요하다. 그 방법으로 하나의 멀티캐스트 서비스에 대하여 세 가지 등급으로 나누어, 각 등급마다 처리할 수 있는 역치(Threshold)를 정하여 제한된 역치 범위 안에서 서비스 요청을 수락할 수 있다. 특히, 시스템 입장에서 등급별 서비스 요청에 대하여 수락 및 거절함에 따른 이익(Reward)과 손실(Penalty)을 근거로 정의되는 시스템 cost 모델인 GAIN을 정의하여 최대한의 이득을 가져올 수 있는 역치의 범위를 정하고, 이를 근거로 서비스 요청을 제어한다. 성능 분석을 위하여 시스템을 M/M/m/m으로 모델링하여 다양한 환경에서 GAIN을 알아보고, 제안된 알고리즘의 효과를 보인다.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1331-1344
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• 2021

This study is to evaluate the seismic capacity of the fire-damaged cabinet facility in a nuclear power plant (NPP). A prototype of an electrical cabinet is modeled using OpenSees for the numerical simulation. To capture the nonlinear behavior of the cabinet, the constitutive law of the material model under the fire environment is considered. The experimental record from the impact hammer test is extracted trough the frequency-domain decomposition (FDD) method, which is used to verify the effectiveness of the numerical model through modal assurance criteria (MAC). Assuming different temperatures, the nonlinear time history analysis is conducted using a set of fifty earthquakes and the seismic outputs are investigated by the fragility analysis. To get a threshold of intensity measure, the Monte Carlo Simulation (MCS) is adopted for uncertainty reduction purposes. Finally, a capacity estimation model has been proposed through the investigation, which will be helpful for the engineer or NPP operator to evaluate the fire-damaged cabinet strength under seismic excitation. This capacity model is presented in terms of the High Confidence of Low Probability of Failure (HCLPF) point. The results are validated by the proper judgment and can be used to analyze the influences of fire on the electrical cabinet.