• 한국해양학회지:바다
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• 제3권4호
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• pp.228-233
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• 1998

본 연구는 비측량용 사진기를 이용한 근거리 사진측정법을 적용하여 해빈단면을 추정하는 방법을 제시한다. 수평면 위에 고정된 비디오로부터 획득한 경사비디오영상을 해석하는 방법을 기초로 다음 두 가지 관점을 고려하여 경사사진 해석에 적합한 방정식을 유도하였다. (1) 사진기가 광축에 대하여 회전되는 것을 허용하였다. (2) 정확도를 향상시키기 위하여 렌즈왜곡을 비롯한 사진 계통상의 오차를 보정하는 단순한 오차모형을 도입하였다. 수정된 방정식을 검증하기 위하여 1998년 2월에 동해시 해빈에서 사진촬영과 정밀한 수준측량을 수행하였다. 그 결과 근거리 사진측정을 통한 해빈단면 추정값과 실제 측량값 사이의 수직거리에 대한 RMS 오차는 10 cm 이내였다.

• 방사성폐기물학회지
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• 제6권4호
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• pp.257-263
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• 2008

중 저준위 방사성패기물 처분장 부지의 지하수 시스템을 개념화하기 위해 부지 내 유동성 배경 단열의 통계적 특성을 분석하였다. 이를 위해 부지 내 시추공에서 얻어진 시추공 로깅 자료의 배경 단열의 주향과 경사 자료를 분석하여 부지 내 배경 단열들을 4개의 단열군으로 분류하였다. 그리고 시추공에서의 수리 시험 결과로 얻어진 시추공 구간별 투수량계수 분포 자료로부터 배경 단열의 투수량계수 분포를 추정하였다. 각 단열군의 단열 크기 분포는 관찰된 단열 밀도와 지표지질조사 자료로부터 유추하였다. 이렇게 얻어진 배경 단열의 통계적 특성을 부지에서 관찰된 투수량계수 분포와 분석 된 통계적 특성을 이용하여 생성된 단열망 모형으로부터 계산된 투수량계수 분포를 비교하여 검증하였고, 검증 결과 관측치와 계산치가 비슷함을 확인하였다.

• 보건행정학회지
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• 제21권1호
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• pp.115-131
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• 2011

Several common issues are encountered by countries - Germany, Japan, and the United States - that adopted long-term care (LTC) system. First, the demand for LTC and its associated costs have steeply risen following the implementation of the LTC policy. Second, ensuring the quality of services have been difficult. Third, the coordination of services among providers and between LTC and medical care has been inadequate. Learning from their experience, we suggest ways to improve the LTC system in Korea. The basic approach aims for efficiency over equity in the system. This would require promoting provider competition and consumer choice. We propose several policy options according to the major stakeholders. For consumers, cash benefits at fixed rates and personal savings accounts are feasible options to self-contain the demand and cost of services. On the insurer's side, creating an environment of multiple insurers will engender competition, leading to cost savings and quality care. For providers, delivery of quality services through competition, cost-containment through capitated reimbursements, and coordination of services through integrated delivery system can be achieved. From the assessors' perspective, establishing an information system to monitor the activities of insurers and providers would be important, empowering consumers with information to choose cost-effective service providers. In summary, the suggested approach would provide cost-effective LTC services by guaranteeing consumer choice and promoting major stakeholder accountability. Further studies are needed to test the feasibility of this model in ensuring quality LTC in Korea.

• The Journal of Advanced Prosthodontics
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• 제6권1호
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• pp.22-29
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• 2014

PURPOSE. This study aimed to investigate the potential clinical application of digitized silicone rubber impressions by comparing the accuracy of zirconia 3-unit fixed partial dentures (FPDs) fabricated from 2 types of data (working model and impression) obtained from a laser scanner. MATERIALS AND METHODS. Ten working models and impressions were prepared with epoxy resin and vinyl polysiloxane, respectively. Based on the data obtained from the laser scanner (D-700; 3Shape A/S, Copenhagen, Denmark), a total of 20 zirconia frameworks were prepared using a dental CAD/CAM system (DentalDesigner; 3shape A/S, Copenhagen, Denmark / Ener-mill, Dentaim, Seoul, Korea). The silicone replicas were sectioned into four pieces to evaluate the framework fit. The replicas were imaged using a digital microscope, and the fit of the reference points (P1, P2, P3, P4, P5, P6, and P7) were measured using the program in the device. Measured discrepancies were divided into 5 categories of gaps (MG, CG, AWG, AOTG, OG). Data were analyzed with Student's t-test ($\alpha$=0.05), repeated measures ANOVA and two-way ANOVA (${\alpha}=0.05$). RESULTS. The mean gap of the zirconia framework prepared from the working models presented a narrower discrepancy than the frameworks fabricated from the impression bodies. The mean of the total gap in premolars (P=.003) and molars (P=.002) exhibited a statistical difference between two groups. CONCLUSION. The mean gap dimensions of each category showed statistically significant difference. Nonetheless, the digitized impression bodies obtained with a laser scanner were applicable to clinical settings, considering the clinically acceptable marginal fit ($120{\mu}m$).

• 대한치과의사협회지
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• 제52권12호
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• pp.734-743
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• 2014

Objectives: By introduced reciprocation motion file in dentistry, dentists benefit simple canal shaping procedure and time-saving. But, reciprocation motion generates uncomfortable vibration to doctors and patients. Because there was no study about this consideration, this study compared vibration pattern and power generated from reciprocation motion motor and conventional rotary motor. Materials & Methods: One conventional rotary motor; X-Smart (Dentsply Maillefer, Ballaigues, Switzerland); and two reciprocating motors; WaveOne Motor (Dentsply Maillefer, Ballaigues, Switzerland) and X-SMART PLUS (Dentsply Maillefer, Ballaigues, Switzerland); were used in this study. Triaxial $ICP^{(R)}$ Accelerometer (Model 356A12, PCB piezotronics, New York, USA) was attached on motor's handpiece head, and was measured tri-axial vibratory acceleration with NI Sound and Vibration Assistant 2009 software (National Instruments, Texas, USA). Mean vibratory acceleration and maximum vibratory acceleration was measured on fixed position and handed position. The results of vibratory acceleration were statistically analyzed using ANOVA and multiple comparisons are made using Turkey's test at p<0.05 level. Results: Reciprocating motors showed higher mean vibratory acceleration and maximum vibratory acceleration than conventional rotary motor (p<0.05). Between reciprocating motors, X-SMART PLUS had lower mean vibratory acceleration and maximum vibratory acceleration than WaveOne Motor (p<0.05). Conclusion: Reciprocating motors generate more vibration than conventional rotary motor. Further study about effect of vibration to dentist and patient is needed. And it seems to be necessary to make a standard about vibration level in endodontic motors.

• 치위생과학회지
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• 제18권3호
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• pp.137-146
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• 2018

This systematic review aimed to investigate the effects of periodontal treatment on glycated hemoglobin A (HbA1c) levels in patients with type 2 diabetes who develop periodontal disease. The search of the MEDLINE, Embase, CINAHL, and Cochrane Library databases was completed on April 8, 2018. The study design was based on randomized clinical trials. Scaling and root planing was performed for the test group, whereas no periodontal treatment or simple oral training was performed for the control group. The main outcome variable was the change in HbA1c levels. We used the Review Manager statistical analysis software for the quantitative analysis of selected documents. Meta-analysis was performed using the inverse variance estimation method of the fixed-effect model to estimate the effects of periodontal treatment on HbA1c levels in patients with type 2 diabetes. A total of 1,011 documents were searched using search strategies, and 10 documents were included in the meta-analysis. The meta-analysis of the selected literature showed that periodontal treatment significantly reduced the HbA1c levels in patients with type 2 diabetes who develop periodontal disease (mean difference, -0.34; 95% confidence interval, -0.43 to -0.26; p<0.001). This study aimed to investigate the effects of periodontal treatment on HbA1c levels, which can be used as a basis for the increasing management of diabetic complications. To improve the quality of life and reduce the burden of medical expenses for patients with diabetes, periodontal disease management through nonsurgical periodontal treatment, such as scaling and root planing, is necessary.

• 한국항해항만학회지
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• 제42권2호
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• pp.127-136
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• 2018

The motion response of floating structures is of significant concern in marine engineering. Floating structures can be disturbed by waves, winds, and currents that create undesirable motions of the vessel, therefore causing challenges to its operation. For a floating structure, mooring lines are provided in order to maintain its position; these should also produce a restoring force when the vessel is displaced. Therefore, it is important to investigate the tension of mooring lines and the motion responses of a twin barge when moored to guarantee the safety of the barge during its operation. It is essential to precisely identify the characteristics of the motion responses of a moored barge under different loading conditions. In this study, the motion responses of a moored twin barge were measured in regular waves of seven different wave directions. The experiment was performed with regular waves with different wavelengths and wave directions in order to estimate the twin-barge motions and the tension of the mooring line. In addition, the motion components of roll, pitch, and heave are completely free. In contrast, the surge, sway, and yaw components are fixed. In the succeeding step, a time-domain analysis is carried out in order to obtain the responses of the structure when moored. As a result, the Response Amplitude Operator (RAO) motion value was estimated for different wave directions. The results of the experiment show that the motion components of the twin barge have a significant effect on the tension of the mooring lines.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권4호
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• pp.330-343
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• 2016

This paper presents results of an experimental investigation of vortex-induced vibration (VIV) of a flexibly mounted and rigid cylinder with two-degrees-of-freedom with respect to varying ratio of in-line natural frequency to cross-flow natural frequency, $f^*$, at a fixed low mass ratio. Combined in-line and cross-flow motion was observed in a sub-critical Reynolds number range. Three-dimensional displacement meter and tension meter were used to measure dynamic responses of the model. To validate the results and the experiment system, x and y response amplitudes and ratio of oscillation frequency to cross-flow natural frequency were compared with other experimental results. It has been found that the higher harmonics, such as third and more vibration components, can occur on a certain part of steel catenary riser under a condition of dual resonance mode. In the present work, however, due to the limitation of a size of circulating water channel, the whole test of a whole configuration of the riser at an adequate scale for VIV phenomenon was not able to be conducted. Instead, we have modeled a rigid cylinder and assumed that the cylinder is a part of steel catenary riser where the higher harmonic motions could occur. Through the experiment, we have found that even though the cylinder was assumed to be rigid, the occurrence of the higher harmonic motions was observed in a small reduced velocity ($V_r$) range, where the influence of the in-line response is relatively large. The transition of the vortex shedding mode from one to another was examined by using time history of x and y directional displacement over all experimental cases. We also observed the influence of in-line restoring force power spectral density with $f^*$.

• 해양환경안전학회지
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• 제23권2호
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• pp.200-207
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• 2017

선박에서 제어판을 가지는 목적은 선박의 운동을 제어하는데 있다. 제어판은 단동타의 형태일수도 있고 고정된 부분과 이동하는 부분의 조합에 의해 구성될 수도 있다. 이러한 제어판은 그 고유의 목적에 맞도록 역할을 수행하는 기능을 가지며, 유체와 상대적인 운동과 원초적인 기능에 의해 조정력을 증가시키는 것이다. 이러한 힘과 모멘트는 영각의 변화와 회전에 의해서 생성되고 선박의 조종성능을 결정한다. 본 논문에서는 플랩러더와 물분사러더의 2차원 유동특성을 회류수조에서 PIV기법을 이용하여 각각 계측하였다. 모델시험은 플랩러더와 물분사러더를 NACA0012의 영각과 플랩각을 변화시키면서 수행하였다. 2프레임 입자추적기법은 유동장에서 속도분포를 득하는데 이용되었다. 전체실험에서 레이놀즈수 $Re{\fallingdotseq}3.0{\times}10^4$를 적용하였으며 상호비교를 통해 계측된 결과값을 비교평가하였다.

• 한국항공우주학회지
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• 제49권6호
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• pp.465-472
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• 2021

고정익 모선과 자선의 공중에서의 분리-재결합 상황에 대한 실제 비행시험 이전에 시뮬레이션을 통해 자선의 비행제어 시스템을 검증할 필요가 있다. 본 논문에서는 X-Plane의 후류 기능을 기반으로 연구실 환경에서 자선의 비행제어 시스템 개발을 위한 시뮬레이션 환경을 구축하였다. 이를 위해 자선의 공력해석을 수행하고 Simulink를 사용하여 항공기를 모사하였으며, X-Plane을 활용하여 시각화와 바람, 돌풍, 모선의 이동을 구현하였다. 유도제어 알고리즘을 Simulink 내 자선 모델에 적용하여 모의 근접비행을 수행함으로써 구축된 시뮬레이션 환경을 검증하였다. 또한 비행 결과를 통해 자선이 모선 후방에서 안전하게 비행할 수 있는 영역을 확인하였다.