• The Journal of Asian Finance, Economics and Business
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• 제9권10호
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• pp.159-168
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• 2022

The time series of foreign trade turnover is complex and variable and contains linear and nonlinear information. This paper proposes preprocessing the dataset by the EMD algorithm and combining the linear prediction advantage of the SARIMA model with the nonlinear prediction advantage of the EMD-LSTM model to construct the SARIMA-EMD-LSTM hybrid model by the weight assignment method. The forecast performance of the single models is compared with that of the hybrid models by using MAPE and RMSE metrics. Furthermore, it is confirmed that the weight assignment approach can benefit from the hybrid models. The results show that the SARIMA model can capture the fluctuation pattern of the time series, but it cannot effectively predict the sudden drop in foreign trade turnover caused by special reasons and has the lowest accuracy in long-term forecasting. The EMD-LSTM model successfully resolves the hysteresis phenomenon and has the highest forecast accuracy of all models, with a MAPE of 7.4304%. Therefore, it can be effectively used to forecast the Sino-Russia foreign trade turnover time series post-epidemic. Hybrid models cannot take advantage of SARIMA linear and LSTM nonlinear forecasting, so weight assignment is not the best method to construct hybrid models.

• 한국분말재료학회지
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• 제30권3호
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• pp.203-209
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• 2023

Aluminum alloy-based additive manufacturing (AM) has emerged as a popular manufacturing process for the fabrication of complex parts in the automotive and aerospace industries. The addition of an inoculant to aluminum alloy powder has been demonstrated to effectively reduce cracking by promoting the formation of equiaxed grains. However, the optimization of the AM process parameters remains challenging owing to their variability. In this study, the response surface methodology (RSM) was used to predict the crack density of AM-processed Al alloy samples. RSM was performed by setting the process parameters and equiaxed grain ratio, which influence crack propagation, as independent variables and designating crack density as a response variable. The RSM-based quadratic polynomial models for crack-density prediction were found to be highly accurate. The relationship among the process parameters, crack density, and equiaxed grain fraction was also investigated using RSM. The findings of this study highlight the efficacy of RSM as a reliable approach for optimizing the properties of AM-processed parts with limited experimental data. These results can contribute to the development of robust AM processing strategies for the fabrication of high-quality Al alloy components for various applications.

• 한국조명전기설비학회지:조명전기설비
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• 제7권3호
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• pp.49-56
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• 1993

본 논문에서는 지하전력구 환경하에서 통신신뢰도가 높고 확장성이 용이하며 복합전송(음성+데이터+영상신호)이 가능한 누설동축케이블을 전송 매체로 하여 지하전력구내 신호전송시스템을 설계 및 설치하였다.그리고 시험시스템에서 각종 전송특성시험을 실시하여 성능을 평가하였다. 음성신호의 경우, 전송손실 특성은 설계치보다 5∼10[dB]정도의 수신레벨이 향상되었으며 통화 품질평가시험에서 통화강도가 3(QSA 값), 명료도가 4(QRK 값)정도의 양호한 특성을 나타냈다. 또한 데이터 및 영상신호 전송특성에 대한 감시제어기능시험에서는 98[%]의 통신성공율을 확보할 수 있었다.그리고 전송로 및 시스템의 전송특성 측정결과에 의해서 중계기 없이 전송범위를 6[km]까지 확대할 수 있는 LCX 통신시스템을 전력구내 종합관리 시스템의 기본 구성방법으로 제시하였다.

• 한국양식학회:학술대회논문집
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• 한국양식학회 2003년도 추계학술발표대회 논문요약집
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• pp.134-135
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• 2003

The geographic expansion of the toxic dinoflagellates genus Alexandrium has been shown to be world wide ranging. The members of the genus Alexandrium ocnstituted of 20-30 species did not show substantial differences in their morphology, which is mostly referred in the 'tamarensis species complex', except some species. Though rDNA sequences variations are very few and pseudogene types are so diverse that it is difficult to use them as the specific markers. In this study, we outlined Korean and Japanese A, tamarense and A. catenella regional isolates by phylogenetic analysis inferred from no cutting alignments of LSU rDNA D1-D2 and SSU rDNA sequences to group these regional isolates. The results were compared to RFLP patterns of PCR products targeted chloroplast DNA. Lastly screening of highly repeated microsatellite DNA which is frequently used for population analysis in eukaryotes was conducted. A. catenella regional strains identified by the sequencing of rDNA D1-D2 domain were divided into at least 3 groups of type E, CMC and Chinese type, divergence root may not be deep comparing with that of A. tamarense whose pseudogenes are very variable. Results of RFLP pattern and the phylogeny of the unknown gene targeting chloroplast showed that Korean and Japanese A. catenella regional isolates were divided into 3 types: Korean, Japanese and the third CMC types. Population-specific PCR amplification with Japanese A. catenella type-specific PCR primers was useful method for population analysis of A. catenella. Various types of satellite sequences such as 5 nucleotides repeats were obtained from A. tamarense and A. catenella. The 5 nucleotides repeats were primed at the both 3'and 5' ends, and these repeats were prominent as longer repeated motifs. This repeated DNA was intercalated as internal sequences containing various types subrepeats. It is expected that these satellite DNA would be a useful molecular population marker through detail comparison among Alexandrium regional isolates to trace their transferring pathway and to prevent their human-associated their regional extents.

• 한국군사과학기술학회지
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• 제17권6호
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• pp.853-860
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• 2014

This paper introduces a Korean rescue robot and presents a whole body kinematic control strategy. The mission of the rescue robot is to move and lift patients or soldiers with impaired mobility in the battlefields, hospitals and hazardous environments. In order for a robot to rescue and assist humans, reliable mobility in various environments, large load carrying capacity, and dextrous manipulability are required. For these objects the robot has variable configuration mobile platform with tracks, dual arm manipulator, and two types of grippers. The electric actuators provide the strength to lift a wounded soldier up to 120 kg using whole body joints. To control the robot with multi degree of freedom, we need to synthesize complex whole-body behaviors, and to manage multiple task primitives systematically. We are to present a whole body kinematic control methodology, and demonstrate its effectiveness through numerical simulations.

• 대한의용생체공학회:의공학회지
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• 제37권6호
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• pp.215-221
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• 2016

Conformity between the femoral component and tibial insert within the knee replacement may be measured in frontal or sagittal view, and shows differences in the curvature radius of the femoral component depending on the flexion angle, i.e., curvature radius has a complex effect on contact stress. Therefore, it is essential to confirm how the curvature radius effects contact stress, and provide an important variable to reduce contact stress. This study correlated contact stress with curvature radius measured in frontal and the sagittal views and confirmed the effect of curvature radius for assessment of the Newly Designed Unicompartment Knee Replacement (NDUKR). Finite element models were constructed for NDUKR and $Zimmer^{(R)}$ Unicompartment High Flex Knee Replacement system (ZUKR), incorporating the curvature radius as measured in either frontal or sagittal view. The femoral component had 1200N of compressive load applied approximately 1.65xbody weight. Contact stress was predicted at flexion angles $0^{\circ}C$, $30^{\circ}C$, $60^{\circ}C$, $90^{\circ}C$ and $120^{\circ}C$, for NDUKR: 42, 47.7, 47.7, 51.2, and 54.1 MPa, and ZUKR: 41.2, 49.5, 53.2, 54.3, and 57.4 MPa, respectively. Correlation analysis showed the influence of curvature radius measured from the sagittal view was larger than for frontal view.

• 한국의류학회지
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• 제42권5호
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• pp.769-785
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• 2018

This study focused on similarities between modern philosophical Nomadism and the thoughts of Korean people as well as analyzed the correlation between modern Nomad fashion and Korean traditional costumes. This study aims are as follows. First, to establish aesthetic characteristics by examining modern Nomadism and Korean thoughts. Second, draw the principles of design expressions of modern Nomad fashion and Korean traditional costumes. Third, analyze correlations between them. The method of this study was a literature review and an analysis of related photos. The study results are as follows. First, Nomadic aesthetics are characterized by the formation of complex diversity with the variability of fusion and separation through liquidity in an ambiguous boundary; in addition, various possibilities and harmony are the characteristics of Korean aesthetics, held by a holistic thought based on the vision of the universe of Qi (氣). Second, Nomad fashion appeared as variable designs through repetition and the overlapping of forms, and irregular designs were noticed through repetition and the overlapping of circles, quadrangles, and angles in Korean traditional costumes. Third, similarities in the creation of liquidity, variability, and de-territoriality based on modules can be found; in addition, common principles can also be drawn from the appearing design expressions.

• 대한기계학회논문집B
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• 제24권2호
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• pp.204-213
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• 2000

This study deals with jet impingement, which is extensively used in the process industries to achieve intense heating, cooling or drying rates and also widely employed as a test flow for turbulent models due to its complex flow configuration, on a flat plate by numerical methods. In this calculation, the finite volume method was employed to solve the Navier-stokes equation based on the non-orthogonal coordinate with non-staggered variable arrangement. To get a better understanding for the fluid flow and heat transfer characteristics of the turbulent jet impingements, $k-{\varepsilon}-{\overline{v^{'2}}}$ turbulent model was adapted and compared with the experimental data and the result of standard $k-{\varepsilon}$ turbulent model. Numerical calculations were carried out with various flow rates, nozzle to plate distances. In the case of the axisymmetric jet impingement on a flat plate, $k-{\varepsilon}-{\overline{v^{'2}}}$ turbulent model showed better agreement with the experimental data than the standard $k-{\varepsilon}$ turbulent model in the prediction of the mean velocity profiles, the turbulent velocity profiles. the turbulent shear stress and the heat transfer rate. The highest heat transfer rate can be obtained when the impingement occurs within the potential core..

• 해양환경안전학회지
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• 제15권3호
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• pp.257-262
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• 2009

일체형 조류제어기인 UPFC는 FACTS 기기중 가장 효과적인 기기 중 하나이다. 본 논문에서는 전력시스템에서 UPFC의 최적위치를 결정하는 데 필요한 컴퓨터의 계산을 줄이는 방법에 대하여 기술한다. 이를 위해 UPFC 제어 변수들과 관련된 발전 비용의 민감도가 평가되었다. 모든 송전선로의 UPFC 민감도를 얻기 위해 단지 한 번의 최적조류제어만으로 해결하였다. 전력시스템에서 UPFC의 최적 위치를 알아내기 위해 여러 권선비와 가변 션트 어드미턴스로 구성된 이상변압기 모델을 사용하였다. 이 모델에서 UPFC 제어 변수들은 UPFC 입 출력의 전류와 전압에 대해서 종속되지 않는다. 민감도 방법은 그의 효율성을 파악하기 위해 IEEE 14 모선에서 파생된 5 모선시스템과 IEEE 14 모선시스템을 대상으로 실험하였다.

• Journal of Chest Surgery
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• 제9권2호
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• pp.175-186
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• 1976

The cellular change of the pulmonary tuberculous lesions may be divided into two groups,exudative and proliferative form by their course and fate. In the most cases, the patients usually have very much complex type of cellular changes. Therefore, the shadows of the chest films in pulmonary tuberculosis are also much variable in nature. And Daniel said that knowledge of the pathology of tuberculosis and an appreciation of the method of progression and healing are essential to proper interpretation of the films. Author, having reviewed 33 cases of resected tuberculous lung obtained in N.M.T.H. for one year from Oct. '75 to Sep. '76 by surgical managements, classified the Pathological findings such as: 1) caseation only, 2) tuberculoma, 3) atelectatic lung 4) cavitary lesion and 5) atelectasis with cavity, and examined the relationship between the roentgenological characteristics of the chest films and the pathological process of tuberculous lesions of the resected lungs, The result were obtained as follows. (1) Tuberculoma was commonly appeared in $S_2$ segment in right and $S_6$ segment in left. (2) Atelectasis and destroyed lung were more commonly appeared in left lung than right, and their containing rate of cavity was 82%. (3) Cavities were mostly appeared in $S_1$ and $S_2$ segments of both lung and the appearance-rate of cavity on $S_6$ segment was higher in left than right. And among the cavitary lesions of the resected lung, cavity was not seen in the preoperative chest films in 22%. (4) The configuration, thickness and sharpness of the walls of cavities, which revealed the cavitary shadows in the preoperative chest films, were mostly depended on the degree of increased collagenous fiber of the wall, existence of perifocalitis, and more or less of the caseous masses on the inner surface of the cavity wall.