In assessing the seismic safety of nuclear power plants, it is essential to analyze the structures using the observed ground motion. In particular, spatial variation in which the characteristics of the ground motion record differ may occur if the location is different within the site and even if the same earthquake is experienced. This study analyzed the spatial variation characteristics of the ground motion observed at the structure and site using the earthquake records measured at the Hamaoka nuclear power plant. Even if they were located on the same floor within the same unit, there was a difference in response depending on the location. In addition, amplification was observed in Unit 5 compared to other units, which was due to the rock layer having a slower shear wave velocity than the surrounding bedrock. Significant differences were also found in the records of the structure’s foundation and the free-field surface. Based on these results, the necessity of considering spatial variation in the observed records was suggested.
PURPOSES : The purpose of this study is to propose a method of quantitative bus deceleration and acceleration time based on automatic vehicle location data generated by a bus operating system.
METHODS : The digital tachometer graph (DTG) data of commercial vehicles and the bus departure and arrival time data collected through the Korean bus information system (BIS) were matched and utilized to accurately reflect the deceleration and acceleration position of the bus. It was determined whether the bus arrived (or departed) at bus stations based on the BIS data, and the acceleration and deceleration times were calculated by classifying the bus status section (deceleration-stop-acceleration-driving) based on the DTG speed data.
RESULTS : The deceleration and acceleration times calculated using the proposed method were analyzed using the z-test for the bus type and peak and non-peak times. Notably, there was a difference in the acceleration time for each vehicle type. The results were compared with the reference values of TCQSM and the calculated values, and the results were similar. CONCLUSIONS : This study is meaningful in that it conducted basic research on calculating the acceleration and deceleration times by fusing currently available data. In addition, new types of buses that have not been presented in the existing reference values have the advantage of being able to be calculated without a separate investigation if only data are produced according to the current bus management system.
PURPOSES : The purpose of this study is to review a method to estimate the average travel speed of the Bus Rapid Transit(BRT) section using the bus departure and arrival time data collected using the Korean bus information system (BIS).
METHODS : To determine an average travel speed estimation model suitable for the BRT system in Korea, the speed estimated using the speed estimation model of TCQSM, which is used in the U.S., and that using the proposed speed estimation model that used the bus departure and arrival time data were compared with the actual travel speed using a t-test.
RESULTS : The average travel speed estimated using the proposed method was more suitable for the actual average travel speed than that estimated using the TCQSM model.
CONCLUSIONS : As a result of estimating the average travel speed, if the length of the link is 900 m, SBRT can be constructed on the existing road, but at least 1,200 m must be ensured to build SBRT in the new city. The proposed bus average travel speed estimation model can be used to review the BRT operational efficiency considering the speed limit, traffic signal, and dwelling time at bus stops in the planning and operation stages of the BRT.
The spatial variation characteristics of seismic motions at the nuclear power plant's site and structures were analyzed using earthquake records obtained at the Fukushima nuclear power plant during the Great East Japan Earthquake. The ground responses amplified as they approached the soil surface from the lower rock surface, and the amplification occurred intensively at about 50 m near the ground. Due to the soil layer's nonlinear characteristics caused by the strong seismic motion, the ground's natural frequency derived from the response spectrum ratio appeared to be smaller than that calculated from the shear wave velocity profile. The spatial variation of the peak ground acceleration at the ground surface of the power plant site showed a significant difference of about 0.6 g at the maximum. As a result of comparing the response spectrums at the basement of the structure with the design response spectrum, there was a large variability by each power plant unit. The difference was more significant in the Fukushima Daiichi site record, which showed larger peak ground acceleration at the surface. The earthquake motions input to the basement of the structure amplified according to the structure's height. The natural frequency obtained from the recorded results was lower than that indicated in the previous research. Also, the floor response spectrum change according to the location at the same height was investigated. The vertical response on the foundation surface showed a significant difference in spectral acceleration depending on the location. The amplified response in the structure showed a different variability depending on the type of structure and the target frequency.
After the manual shutdown of the Wolseong nuclear power plant due to an earthquake in Gyeongju in 2016, anxiety about the earthquake safety of nuclear power plants has become a major social issue. The shear wall structure used as a major structural element in nuclear power plants is widely used as a major structural member because of its high resistance to horizontal loads such as earthquakes. However, due to the complexity of the structure, it is challenging to predict the dynamic characteristics of the structure. In this study, a three-story shear wall structure is fabricated, and the in-structure response characteristics of the shear wall structure are evaluated through shaking table tests. The test is performed using the Gyeongju earthquake that occurred in 2016, and the response characteristics due to the domestic earthquake are evaluated.
Pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, seismic coefficient (kh), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. Therefore, the calculation of an appropriate kh considering frequency characteristics of input earthquake is critical for representing the real dynamic behavior. However, the definitions of kh, which is used for simplified analysis in Korea, focuses only on convenience that is easy to use, and the frequency characteristics of input earthquake are not reflected in the kh definitions. This paper evaluates the influences of the frequency characteristics of input earthquake on kh by initially reviewing the kh definitions in the existing codes of Japan for port structures and then by performing a series of dynamic centrifuge tests on caisson gravity quay walls of different earthquake input motions (Ofunato, Hachinohe). A review of the existing codes and guidelines has shown that the kh values are differently estimated according to the frequency characteristics of input earthquake. On the other hand, based on the centrifuge tests, it was found that the permanent displacements of wall are more induced when long-period-dominant earthquake is applied.
This study reviews concepts, theories and formulas included in standards on soil-structure interaction and also shows practical example of application for engineers. Real structures are 3 dimensional and multi degree of freedom but they are often idealized to single degree of freedom for convenience. In this study, detailed procedures to calculate soil spring constants and damping coefficients and method to model soil-structure system are explained. Additionally, case studies to judge fixed base condition and evaluation of applicability of simple analysis method based on response spectra are performed.
LC-MS/MS를 이용하여 신속하고 정밀한 카벤다짐 분석법을 연구하였다. 농산물 중 카벤다짐은 acetonitrile로 추 출한 후 SPE cartridge을 이용하여 전처리를 수행하였으며, 최소 검출한계 및 정량한계는 각각 0.001과 0.004 mg/kg 이었다. 농산물에 각각 1.0 mg/kg 및 0.02 mg/kg 농도의 카벤다짐을 첨가하여 분석 시 회수율과 정밀성은 각각 상추 가 84.9%, 1.0% 및 87.8%, 3.8% 얼갈이배추가 83.4%, 1.5% 및 86.8%, 2.7% 양배추가 86.4%, 2.0% 및 77.3%, 1.5% 근대가 83.3%, 0.2% 및 86.8%, 2.0 % 이었으며, 콩 나물은 85.9%, 3.0% 및 90.1%, 1.3%, 그리고 숙주나물이 83.3%, 2.0% 및 85.9%, 1.9% 로 조사되었다. 본 연구의 시험법은 식품공전의 다성분분석법에 비해 신속하고 정밀 한 분석법으로 농산물에 대한 카벤다짐 분석에 적합한 것으로 조사되었다.
Neodymium-iron-boron (Nd-Fe-B) sintered magnets have excellent magnetic properties such as the remanence, coercive force, and the maximum energy product compared to other hard magnetic materials. The coercive force of Nd-Fe-B sintered magnets is improved by the addition of heavy rare earth elements such as dysprosium and terbium instead of neodymium. Then, the magnetocrystalline anisotropy of Nd-Fe-B sintered magnets increases. However, additional elements have increased the production cost of Nd-Fe-B sintered magnets. Hence, a study on the control of the microstructure of Nd-Fe-B magnets is being conducted. As the coercive force of magnets improves, the grain size of the Nd2Fe14B grain is close to 300 nm because they are nucleation-type magnets. In this study, fine particles of Nd-Fe-B are prepared with various grinding energies in the pulverization process used for preparing sintered magnets, and the microstructure and magnetic properties of the magnets are investigated.
Soil-foundation-structure interaction (SFSI) is one of the important issues in the seismic design for evaluating the exact behavior of the system. A seismic design of a structure can be more precise and economical, provided that the effect of SFSI is properly taken into account. In this study, a series of the dynamic centrifuge tests were performed to compare the seismic response of the single degree of freedom(SDOF) structure on the various types of the foundation. The shallow and pile foundations were made up of diverse mass and different conjunctive condition, respectively. The test specimen consisted of dry sand deposit, foundation, and SDOF structure in a centrifuge box. Several types of earthquake motions were sequentially applied to the test specimen from weak to strong intensity of them, which is known as a stage test. Results from the centrifuge tests showed that the seismic responses of the SDOF structure on the shallow foundation and disconnected pile foundation decreased by the foundation rocking. On the other hand, those on the connected pile foundation gradually increased with intensity of input motion. The allowable displacement of the foundation under the strong earthquake, the shallow and the disconnected pile foundation, have an advantage in dissipating the earthquake energy for the seismic design.
To investigate earthquake responses of structures with basements affected by soil deposits, centrifuge tests were performed using an in-flight earthquake simulator. The test specimen was composed of a single-degree-of-freedom structure model, a basement and sub-soil deposits in a centrifuge container. The test parameters were the dynamic period of the structure model, boundary conditions of the basement, existence of soil deposits, centrifugal acceleration level, and type and level of input earthquake accelerations. When soil deposits did not exist, the earthquake responses of the structures with fixed basement were significantly greater than those of the structure without basement. Also, the earthquake responses of the structures with the fixed basement surrounded by soil deposits were amplified, but the amplifications were smaller than those of the structures without basement. The earthquake responses of the structures with the half-embedded basement in the soil deposits were greater than those estimated by the fixed base model using the measured free-field ground motion. The test showed that the basement and the soil deposit should be simultaneously considered in the numerical analysis model, and the stiffness of the half-embedded was not effective.
This study was conducted to establish the techniques of the continuous wheat production of high yield level and to standardize of quality uniformity. It was selected the experimental places which were Iksan of Jeonbuk, Gwangju metropolitan city and Hapcheon of Gyeongnam. Farmers of participating in the experiment were 13 persons with two types of advanced and lower levels of their techniques in wheat cultivation, and total numbers of fields were 22 fields. The common information on the field soils were silt loam and loam in soil textures, all most deep and some moderate in soil depth, imperfectly drained in drainage classes, coastal and interior plain with some alluvial fan or local valley in land topography. It was investigated in status of the physico-chemical properties of soils. Soil pH was 6.0 in mean values with 5.2 ~ 7.5 ranges, organic matter(OM) was 25 g/kg with 16 ~ 39 ranges, available P2O5 194mg/kg with 47 ~ 586 ranges, available SiO2 164mg/kg with 57 ~ 454 ranges, in exchangeable cations, K was 0.46 with 0.20 ~ 0.98, Ca was 6.2 with 3.6 ~ 11.7, Mg was 1.8 with 0.9 ~ 3.4 cmol(c)/kg in ranges, and these properties of soils were higher in advanced than those of lower level farmers. The amounts of fertilization in N-P2O5-K2O were 184-49-50 kg/ha in farmers application, 108-114-47 kg/ha in soil testing and 94-83-41kg/ha in standard recommendation. Fertilizer application amounts by farmers were higher than those of soil testing and standard recommendation by 76 ~ 90 kg/ha in N and 3 ~ 9 kg/ha in K2O, and less by 34 ~ 74 kg/ha in phosphate fertilizer.
내시경 역행 췌담관조영술 중 경췌중격절개술은 선택적 담관 삽관이 어려운 환자에서 성공률을 높일 수 있는 방법으로 알려져 있다. 최근 후향적 연구에서는 경췌중격절개술이 침형절개도를 이용한 조임근절개술보다 효과적이며 안전한 것으로 보고되었다. 그러나 이번 증례에서 담석췌장염 환자에서 경췌중격절개술 후 벽내 십이지장 혈종 및 십이지장 폐쇄가 발생하였고 이로 인해 저혈량쇼크 등 치명적인 합병증이 발생하였다. 따라서 급성 췌장염이 동반된 환자에서 내시 경역행췌담관조영술 중 경췌 중격절개술을 시행한 후에는 벽내 십이지장 혈종과 같은 합병증 발생 여부를 주의 깊게 관찰할 필요가 있다고 생각된다.
국내에서 생산되어 시판되고 있는 보리쌀 제품을 수집하여아밀로오스와 β-glucan 함량을 분석하고 아밀로오스 함량에 따른 찰성 및 메성 보리쌀의 호화 및 취반 특성을 비교하였다.보리쌀 제품은 제품에 표기된 바에 따라 찰보리쌀과 메보리쌀로 분류하여 이들의 아밀로오스 함량을 측정하였다. 분석결과보리쌀 제품의 아밀로오스 함량은 4.46 ~ 30.68% (평균 16.33%)로 다양하게 나타났으며, 찰보리쌀 제품은 대부분 아밀로오스함량이 5 ~ 10% 정도의 분포를 보였다. 보리쌀 제품의 β-glucan 함량은 2.49 ~ 6.79% 범위(평균 4.57%)로 분석되었다.시판 보리쌀 제품을 찰보리쌀(아밀로오스 10% 이하)과 메보리쌀(아밀로오스 20% 이상) 그룹으로 구분하여 각각 선발한보리쌀 제품을 비교하였으며, 찰보리쌀이 메보리쌀에 비해 β-glucan 함량이 약 2% 높게 나타났다. 찰보리쌀은 메보리쌀에비해 신속점도측정기(RVA)에 의한 호화개시온도, 최고점도,trough, breakdown, 최종점도, setback이 낮게 나타났다. 보리쌀의 취반특성에서 시판 찰보리쌀은 메보리쌀에 비해 수분흡수율과 퍼짐성은 높은 반면 용출고형분이 낮았으며, 텍스쳐(경도)는 찰보리쌀이 낮아 보리밥의 취반특성 및 식감이 보다 좋은 것으로 평가되었다.
To investigate the usefulness of Kenaf(Hibiscus cannabinus L.) as mushroom culture media source, we analyzephysical condition and contents of nutritional components. The water absorption rate of Kenaf bast was 578% and it was 95%higher than that of poplar sawdust’s. This was caused by Kenaf’s porous cellular structure. so it could give more moisture andoxygen to cultured mushroom. Total carbon contents of Kenaf was 91.4%, it was quite higher than that of poplar sawdust, wheatbran and rice bran. Total nitrogen content was 1.76% and C/N ratio was 51.9. The content of NFE(Nitrogen free extract) was46.6% and it was similar with rice bran. Cellulose content was higher than poplar but lignin content was lower. speciallyhemicellulose and pectin complex which more digestible carbon source to mushroom was 3.7% higher than poplar. Mineralcomponent and amino acid contents were also maintained high compared with poplar. Fe was 4.2 times, P 3.2 times, K 2.2times more and Ca was higher 16 mg/kg than poplar. The content of amino acid was quite more higher than poplar sawdust butlower than chaff. Consequently Kenaf had a good trait for basic support material in mushroom culture media and also had agood character as nutritional source.
본 연구는 국내 재배면적이 확대되고 있는 목이버섯의 부가가치 향상과 소비량 확대를 위해 팽화기술을 접목한 목이버섯 즉석죽을 제조하고, 품질특성을 조사하여 실버층에 쉽게 적용할 수 있는 제품을 개발하고자 하였다. 백미와 흑미를 75~100%와 25~0%로 혼합한 후 비타민 D2와 식이섬유 함량이 높은 건목이버섯을 0~4%로 첨가하여 호화도, 영양성분, 항산화성 및 관능 등을 조사하였다. 즉석죽 분말의 호화도는 건목이버섯 첨가량이 증가할수록, 흑미 첨가량이 감소할수록 최고점도와 유지강도, 강하점도, 최종점도, 노화점도가 증가하는 경향이었다. 백미 80%와 흑미 20%를 혼합한 후 건목이버섯 3%를 첨가한 즉석죽은 비타민 D2 18.53 μg/100 g, 식이섬유 3.73 g/100 g이 함유되어 있어 뼈의 형성과 유지와 배변활동 촉진 효과가 기대되었다. 또한 DPPH free radical 소거능도 56.79%로 나타나, 항산화성이 높아 실버층의 건강에 기여할 것으로 기대되었다. 본 실험 결과, 목이버섯은 기능성 가공제품 개발의 소재로서 사용가치가 매우 높아 실버층뿐 아니라, 다양한 연령층에 적합한 가공제품 생산에 응용가능하리라 생각된다.
This paper reviews the current seismic design code and research for dynamic earth pressure on retaining structures. Domestic design codes do not clearly define the estimation of dynamic earth pressure and give different comments for seismic coefficient, wall inertia and distribution of dynamic earth pressure using Mononobe-Okabe method. AASHTO has been revised reflecting current research and aims for effective seismic design. Various design codes are analyzed to compare their performance and economic efficiency. The results are used to make improvement of current domestic seismic design code. Further, it is concluded that the experimental investigation is also needed to verify and improve domestic seismic code for dynamic earth pressure.