• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.64-71
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• 2009

The stresses acting on shotcrete lining of tunnel have been measured virtually by monitoring instruments installed during construction. However, the malfunction of instrument and the lack of consistency of signal have always been controversial, but re-installation of instrument after construction of tunnel lining is practically impossible. Therefore, authors have carried out the study to develop a new technique for estimating the stress acting on shotcrete lining during and after construction. In the technique, stresses of shotcrete lining can be estimate by the measurement of deformation of free face. Therefore, the relationships between the stresses of shotcrete lining and deformation of free surface are indispensable factor. In this paper, the parametric study using 2D FEM analysis was carried out to estimate the relationships between the stress level acting on the tunnel shotcrete lining and the deformation near the free face (e.g. artificial crack in this study). The distribution of stresses of shotcrete lining is also investigated in this study as the preliminary investigation for the large-scale tunnel lining test and detailed 3D FEM analysis.

• 대한조선학회논문집
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• 제29권3호
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• pp.80-89
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• 1992

자유표면파 문제에서의 방사조건을 위해 두가지 기법을 적용하여 보았다. 우선, 가상감쇠의 개념을 적용하여 일정한 구간에서 파를 감쇠시킴으로써 열린경계면(open boundary)에서 반사파를 제거하는 방법을 적용하여 보았다. 또 다른 방법으로서는 Orlanski의 방법을 변형하여 적용함으로써 단방향 파동에 대한 방사조건 처리기법을 다루었다. 몇가지의 전형적인 자유표면파문제에 대해 이들 기법을 적용하여 그 유용성을 고찰하였는데, 이들 기법은 그 적용방법이 간단하고 비선형문제에서도 사용될 수 있을 것으로 사료된다. 문제의 해법으로 기본 쏘오스 분포법이 사용되었고 비선형의 자유표면 경계조건이 적용되었다.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.797-806
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• 2012

Fault detection and isolation (FDI) algorithms provide fault monitoring methods in GPS measurement to isolate abnormal signals from the GPS satellites or the acquired signal in receiver. In order to monitor the occurred faults, FDI generates test statistics and decides the case that is beyond a designed threshold as a fault. For such problem of fault detection and isolation, this paper presents and evaluates position domain integrity monitoring methods by formulating various pseudorange prediction methods and investigating the resulting test statistics. In particular, precise measurements like carrier phase and Doppler rate are employed under the assumption of fault free carrier signal. The presented position domain algorithm contains the following process; first a common pseudorange prediction formula is defined with the proposed variations in pseudorange differential update. Next, a threshold computation is proposed with the test statistics distribution considering the elevation angle. Then, by examining the test statistics, fault detection and isolation is done for each satellite channel. To verify the performance, simulations using the presented fault detection methods are done for an ideal and real fault case, respectively.

• 산경연구논집
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• 제11권3호
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• pp.7-17
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• 2020

Purpose: This study reexamines the test on the pricing of accruals quality. Theory suggests that information risk is a priced risk factor. Using accruals quality as the proxy for information risk, researchers have tested the pricing of information risk. The results are inconsistent potentially because of the information shock in the realized returns that are used as the proxy for expected returns. Based on this argument, this study revisits this issue excluding information-shock-free measure of expected returns. Research design, data and methodology: This study estimates expected returns using the vector autoregression model. This method extracts information shocks more thoroughly than the methods in prior studies; therefore, the concern regarding information shock is minimized. As risk premiums are larger in recession periods than in expansion periods, recession and expansion subsamples were used to confirm the robustness of the main findings. For the pricing test, this study uses two-stage cross-sectional regression. Results: Empirical results find evidence that accruals quality is a priced risk factor. Furthermore, this study finds that the pricing of accruals quality is observed only in recession periods. Conclusions: This study supports the argument that accruals quality, as well as the pricing of information risk, is a priced risk factor.

• Tribology and Lubricants
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• 제36권3호
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• pp.161-167
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• 2020

Petroleum is the most used energy source in Korea with a usage rate of 39.5% among the available 1st energy source. The price of liquid petroleum products in Korea includes a lot of tax such as transportation·environment·energy tax. Thus, illegal production and distribution of liquid petroleum is widespread because of its huge price difference, including its tax-free nature, from that of the normal product. Generally, illegal petroleum product is produced by illegally mixing liquid petroleum with other similar petroleum alternatives. In such case, it is easy to distinguish whether the product is illegal by analyzing its physical properties and typical components. However, if one the components of original petroleum product is added to illegal petroleum, distinguishing between the two petroleum products will be difficult. In this research, we inspect illegally produced gasoline, which is mixed with methyl tertiary butyl ether (MTBE) as an octane booster. This illegal gasoline shows a high octane number and oxygen content. Further, we analyze the different types of green dyes used in illegal gasoline through high performance liquid chromatography (HPLC). We conduct component analyses on the simulated sample obtained from premium gasoline and MTBE. Finally, the illegal gasoline is defined as premium gasoline with 10% MTBE. The findings of this study suggest that illegal petroleum can be identified through an analytic method of components and simulated samples.

• 대한기계학회논문집A
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• 제26권3호
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• pp.479-486
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• 2002

In this study, the progressive inelastic deformation, so called, thermal ratchet phenomenon which can occur in high temperature structures of liquid metal reactor was simulated with thermal ratchet structural test facility and 316L stainless steel test cylinder. The thermal ratchet deformation at the reactor baffle cylinder of the liquid metal reactor can occur due to the moving temperature distribution along the axial direction as the sodium free surface moves up and down under the cyclic heat-up and cool-down transients. The ratchet deformation was measured with the laser displacement sensor and LVDTs after cooling the structural specimen which is heated up to 55$0^{\circ}C$ with steep temperature gradients along the axial direction. The temperature distribution of the test cylinder along the axial direction was measured with 28 channels of thermocouples and was used for the ratchet analysis. The thermal ratchet deformation was analyzed with the constitutive equation of nonlinear combined hardening model which was implemented as ABAQUS user subroutine and the analysis results were compared with those of the test. Thermal ratchet load was applied 9 times and the residual displacement after 9 cycles of thermal load was measured to be 1.79mm. The ratcheting deformation shapes obtained by the analysis with the combined hardening model were in reasonable agreement with those of the structural tests.

• 한국추진공학회지
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• 제26권4호
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• pp.10-20
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• 2022

한국항공우주연구원의 자유제트형 지상추진시험설비인 스크램제트 엔진 시험설비의 마하 5 조건에서 스크램제트 엔진 흡입구의 성능분석 시험을 진행하였다. 스크램제트 엔진 흡입구의 대표적인 성능 인자인 전압력 회복률, 공기 포획율 측정을 위하여 격리부 후방에 설치되는 피토/정압 레이크가 설계 제작되었다. 격리부 후방에 장착된 레이크가 전방의 흡입구 램프와 격리부에 미치는 영향과 레이크로 측정된 흡입구의 성능 인자 분석 그리고 흡입구의 받음각 변화에 따른 벽면 정압력 분포 변화에 대한 분석이 수행되었다. 끝으로 연소기에서의 압력 상승을 모사하는 장치인 흡입구 후방 배압 조정 장치를 이용하여 흡입구 불시동이 발생하는 시점을 확인하였으며, 본 논문에는 그 결과를 정리하였다.

• Journal of Pharmaceutical Investigation
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• 제24권3호
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• pp.167-176
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• 1994

The microcapsules of amoxicillin using stearyl alcohol and polyethyleneglycol 8000 (PEG 8000) were prepared by a emulsion melted-cooled process in water phase. The size distribution, dissolution test, observation with SEM and in vivo test were investigated. The microcapsules obtained were spherical, uniform and free flowing particles. The release of drug from microcapsule was increased in proportional to the content of PEG 8000. As the PEG 8000 content increased, the particle size of microcapsule was decreased. Sanning electron micrograph study revealed that microcapsules had comparatively rough surfaces as drug content was increased. The $AUC_{0-12}$ after administration of amoxicillin microcapsules was more increased 40% as compared with the AUC after administration of amoxicillin powder in rabbits.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.733-742
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• 2020

Taking the cylindrical float of the floating fence of a floating litter collection device as the research object, based on the shallow immersion characteristics of the cylindrical float, the Morison equation is modified, and the interaction between regular waves and the partially immersed horizontal cylindrical float is discussed in combination with scale model test. The results show that the modified Morison equation can accurately predict the wave force of the horizontal cylindrical float and reveal the influence of amplitude, immersion depth and period on the wave force of the cylindrical float. For partially immersed cylindrical floats, the wave force increases with the increase in wave height and decays with the increase in period. The positive value distribution of the wave force is larger than that of the negative direction, and the difference between the positive and negative directions is mainly affected by the immersion depth.

• 한국관광식음료학회지:관광식음료경영연구
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• 제12권2호
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• pp.1-41
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• 2001

The effect of smoking on the quality sausage Sausages were prepared from beef, port, chickens, games, fish and shellfish with polyphosphate salt and spices. Sausage history goes back to 3,000 years of age. The procedure of sausage 1) Meat Curing 2) Meat Control 3) Add Spices 4) Permissible Ingredients 5) Grinding 6) Mixing Emulsion 7) Stuffing 8) Showing 9) Smoking 10) Cooking 11) Drying 12) Packaging Sausage Product to get information on the effect of smoking onto the quality of meat produces. Sausage was smoked under a given conditions. Smoking was conducted as 35f$^{\circ}C$to 6$0^{\circ}C$ the related humidity of smokehouse was still at 60 to 70 percent. Results are as follows: 1. The Penetrated smoke in sausage was prolonged < p.<0.02 when sausage was smoked 2hours at 60~$65^{\circ}C$ the penetrated amount of free acetone in sausage was 0.5mg%. 2. Peroxide value of sausage as heating treatment both at 3$0^{\circ}C$ and at 5$0^{\circ}C$ was prolonged. 3. When sausage was heated at 3$0^{\circ}C$, bacteria of sausage increased In number while at 60~$65^{\circ}C$ bacteria of sausage increased In number fourteen hours. 4. When sausage was treated with smoking the distribution of free amino acids in sausage was changed markedly. 5. The longer smoking time of the products was the higher the content. 6. In case of oak wood smoke flavoring all of test samples. 7. Rapid decrease of does-response mutagenic curve of the smoke flavoring of oak wood and apple wood by in the peak of curve and phenol in the smoke flavoring. Continuous efforts are required to make sausages easily in the butcher shops and in the restaurants. 8. Sausage texture evaluation has 13 rules. It is Elasticity, Surface Moisture, Surface Smoothness, Center Hardness, Skin Toughness, Cohesiveness, Denseness, Moisture Release, Cohesiveness of Mass, Lumpiness, Graininess (of Contents), Skin separation, Oiliness and sensory 11 rules evaluation is color, texture, mold, flavor, sweet test, salty, sourness, bitter, and savory taste. 9. Smoked, component, peroxide value, bacteria, color, free amino acid, tenderness, flavor, shrinkage are important values.