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1D Wavelet Filtering for Groundroll Suppression in Land Seismic-Reflection Data
( Jin-hyeon Sa ),( Jae-eun Lee ),( Sung-soo Kim ),( Ji-soo Kim ) 대한지질공학회 2017 지질공학 Vol.27 No.4
Groundroll is a coherent noise showing dispersive behavior in land seismic-reflection records and its rejection has been a stubborn problem in data processing because they severely degrade the continuities and resolution of reflection signals. Conventional processing schemes of attenuating noises are the kind of frequency filtering (i.e., bandpass and f-k) that uses the Fourier transform (FT) along the entire trace in the time domain. To suppress them in this study, 1D wavelet filtering (WT) that can control time-varying frequency properties is tested and performed in the land-based synthetic and field seismic data. The results are compared to the ones from conventional filtering techniques in terms of continuities and resolution of reflection events. This filtering technique enhanced the reflection events by effectively eliminating the dispersive groundroll and random noises with control of time-scale function on wavelet domain.
Park Hyeon,Sa Kyu Jin,Lee Sookyeong,Lee Ju Kyong 한국유전학회 2022 Genes & Genomics Vol.44 No.10
Background: In order to maximize the use of valuable native Perilla germplasm in South Korea, knowledge of the Perilla seed oil content and genetic variation among native Perilla germplasm resources is very important for the conservation and development of new Perilla seed oil varieties using the native Perilla germplasm accessions preserved from the Rural Development Administration Genebank (RDA-Genebank) collection from South Korea. Objectives: In this study, we studied population structure and association mapping to identify Perilla SSR markers (PSMs) associated with the five fatty acid contents and two seed characteristics of the native Korean Perilla germplasm accessions of cultivated var. frutescens of the RDA-Genebank collected in South Korea. Methods: For an association mapping analysis to find PSMs associated with the five fatty acid contents and two seed characteristics of the Perilla germplasm accessions of cultivated var. frutescens, we evaluated the content of five fatty acids of 280 native Korean Perilla germplasm accessions and used 29 Perilla SSR primer sets to measure the genetic diversity and relationships, population structure, and association mapping of the native Korean Perilla germplasm accessions of the RDA-Genebank collected in South Korea. Results: Five fatty acids of 280 native Korean Perilla accessions were identified as follows: palmitic acid (PA) (5.30-8.66%), stearic acid (SA) (1.60-4.19%), oleic acid (OA) (9.60-22.5%), linoleic acid (LA) (8.38-25.4%), and linolenic acid (LNA) (52.7-76.4%). In a correlation analysis among the five fatty acids and two seed characteristics of the 280 Perilla accessions, the combinations of PA and SA (0.794**) and SA and OA (0.724**) showed a particularly high positive correlation coefficients compare to other combinations. By using an association analysis of the 29 PSMs and the five fatty acids in the 280 Perilla accessions, we found 17 PSMs (KNUPF1, KNUPF2, KNUPF4, KNUPF10, KNUPF16, KNUPF25, KNUPF26, KNUPF28, KNUPF37, KNUPF55, KNUPF62, KNUPF71, KNUPF74, KNUPF77, KNUPF85, KNUPF89, and KNUPF118) associated with the content of the five fatty acid components and two seed characteristics. Conclusions: These PSMs are considered to be useful molecular markers related to five fatty acid components and two seed characteristics for selecting accessions from the germplasm accessions of the Perilla crop and their related weedy types through association mapping analysis and marker-assisted selection (MAS) breeding programs.
특이값 분해를 이용한 육상 탄성파자료의 그라운드롤 제거
사진현 ( Jin-hyeon Sa ),김성수 ( Sung-soo Kim ),김지수 ( Ji-soo Kim ) 대한지질공학회 2018 지질공학 Vol.28 No.3
육상 탄성파자료에 나타나는 일관성 잡음인 그라운드롤을 제거하기 위해 특이값 분해 필터링의 적용성을 살펴보았다. 상관성이 높은 반사에너지가 요구되는 특이값의 계산을 위해 먼저 자동이득제어로 감쇠된 진폭을 보상하고 송수신점의 높이보정 및 풍화대 보정을 실시하여 장파장 시간차이를 제거한 후, 나머지 정적보정으로 단파장 시간차이를 완화시켜 반사면의 수평적인 연속성을 높였다. 특이값 분해 필터링에 적합한 입력인자(최대 주성분)는 공통중간점 자료에 수직시간차 역보정을 수행하여 얻은 공통발파점 자료에 대한 연속 테스트로 결정하였다. 그라운드롤의 시간에 따른 분산이 뚜렷한 현장자료에서 특이값 분해 필터링은 일반적인 기법인 f-k 필터링에 비해 반사신호의 왜곡없이 그라운드롤의 영향을 최소화하면서 주요 반사면들의 연속성을 향상시키는데, 이것은 진폭 빛띠에서 반사파의 낮은 진동수 성분들이 필터링 후에도 보존되었다는 점과 잘 상관되었다. 특히 특이값 분해 필터링을 거친 후 S/N 비를 높일 수 있는 자료처리(송곳곱풀기, 시간변화 빛띠흰색화) 과정을 함께 수행하여 겹쌓기한 결과 저류층을 포함한 주요 반사면들의 향상된 연속성과 분해능을 확인할 수 있었다. The application of singular value decomposition (SVD) filtering is examined for attenuation of the ground-roll in land seismic data. Prior to the SVD computation to seek singular values containing the highly correlatable reflection energy, processing steps such as automatic gain control, elevation and refraction statics, NMO correction, and residual statics are performed to enhance the horizontal correlationships and continuities of reflections. Optimal parameters of SVD filtering are effectively chosen with diagnostic display of inverse NMO (INMO) corrected CSP (common shot point) gather. On the field data with dispersion of ground-roll overwhelmed, continuities of reflection events are much improved by SVD filtering than f-k filtering by eliminating the ground-roll with preserving the low-frequency reflections. This is well explained in the average amplitude spectra of the f-k and SVD filtered data. The reflectors including horizontal layer of the reservoir are much clearer on the stack section, with laminated events by SVD filtering and subsequent processing steps of spiking deconvolution and time-variant spectral whitening.
( Hyeon-tae Ju ),( Jin-hyeon Sa ),( Ji-soo Kim ) 대한지질공학회 2017 지질공학 Vol.27 No.3
The most effective way to distinguish subsurface interfaces that produce various geophysical responses is through the integration of multiple geophysical methods, with each method detecting both a complementary and unique set of distinct physical properties relating to the subsurface. In this study, shallow seismic reflection (SSR) and ground penetrating radar (GPR) surveys were conducted at the Cheongju-Gadeok site of the Korea National Groundwater Monitoring Network to map the water table, which was measured at 12 m depth during the geophysical surveys. The water table proved to be a good target reflector in both datasets, as the abrupt transition from the overlying unsaturated weathered rock to the underlying saturated weathered rock yielded large acoustic impedance and dielectric constant contrasts. The two datasets were depth converted and integrated into a single section, with the SSR and GPR surveys conducted to ensure subsurface imaging at approximately the same wavelength. The GPR data provided detailed information on the upper ~15 m of the section, whereas the SSR data imaged structures at depths of 10-45 m. The integrated section thus captured the full depth coverage of the sandy clay, water table, weathered rock, soft rock, and hard rock structures, which correlated well with local drillcore and water table observations. Incorporation of these two geophysical datasets yielded a synthetic section that resembled a simplified aquifer model, with the best-fitting seismic velocity, dielectric constant, and porosity of the saturated weathered layer being v<sub>seismic</sub> = 1000 m/s, ε<sub>r</sub> = 16, and φ = 0.32, respectively.
Sa, Young Jin,Seo, Dong-Jun,Woo, Jinwoo,Lim, Jung Tae,Cheon, Jae Yeong,Yang, Seung Yong,Lee, Jae Myeong,Kang, Dongwoo,Shin, Tae Joo,Shin, Hyeon Suk,Jeong, Hu Young,Kim, Chul Sung,Kim, Min Gyu,Kim, Tae American Chemical Society 2016 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.138 No.45
<P>Iron-nitrogen on carbon (Fe-N/C) catalysts have emerged as promising nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in energy conversion and storage devices. It has been widely suggested that an active site structure for Fe-N/C catalysts contains Fe-N-x coordination. However, the preparation of high-performance Fe-N/C catalysts mostly involves a high-temperature pyrolysis step, which generates not only catalytically active Fe-N-x sites, but also less active large iron-based particles. Herein, we report a general 'silica-protective-layer-assisted' approach that can preferentially generate the catalytically active Fe-N-x sites in Fe-N/C catalysts while suppressing the formation of large Fe-based particles. The catalyst preparation consisted of an adsorption of iron porphyrin precursor on carbon nanotube (CNT), silica layer overcoating, high-temperature pyrolysis, and silica layer etching, which yielded CNTs coated with thin layer of porphyrinic carbon (CNT/PC) catalysts. Temperature-controlled in situ X-ray absorption spectroscopy during the preparation of CNT/PC catalyst revealed the coordination of silica layer to stabilize the Fe-N-4 sites. The CNT/PC catalyst contained higher density of active Fe-N-x sites compared to the CNT/PC prepared without silica coating. The CNT/PC showed very high ORR activity and excellent stability in alkaline media. Importantly, an alkaline anion exchange membrane fuel cell (AEMFC) with a CNT/PC-based cathode exhibited record high current and power densities among NPMC-based AEMFCs. In addition, a CNT/PC-based cathode exhibited a high volumetric current density of 320 A cm(3) in acidic proton exchange membrane fuel cell. We further demonstrated the generality of this synthetic strategy to other carbon supports.</P>
Hyeon-Jeong Yang,Seok Joon Yoon,Jong Sung Kim,Sung Soo Kim,Jin Gyu Jung,Won Yoon Suh,Sa-Mi Lee,Hyun Gu Kim,YongwooLee 대한가정의학회 2021 Korean Journal of Family Medicine Vol.42 No.4
Background: The simplified Palliative Prognostic Index (sPPI) substitutes a single item from the Communication Capacity Scale (CCS) for the delirium item of the original PPI. This study aimed to examine the validity of the sPPI for patients with advanced cancer in a home-based hospice care setting. Methods: This study included 75 patients with advanced cancer who received home-based hospice care. We used medical records maintained by professional hospice nurses who had visited the patients in their homes. Based on their sPPI score, patients were divided into three groups—A (<4), B (≥4 and <6), and C (≥6)—to compare survival. Further, we investigated the sPPI’s accuracy using the area under the receiver operating characteristic curve (AUC) and sensitivity and specificity for 3- and 6-week survival. We used three sPPIs including different substitutions for the delirium item (two methods using the CCS and one using the Korean Nursing Delirium Screening Scale). Results: The median survival was 60–61 days for group A, 27–30 days for group B, and 12–16 days for group C. The difference in survival was significant (P<0.05). The AUC was 0.814–0.867 for 3-week survival and 0.736–0.779 for 6-week survival. For 3- and 6-week survival, prognostic prediction showed sensitivities of 76.2%–90.9% and 76.3%– 86.8%, and specificities of 64.2%–88.7% and 51.4%–70.3%, respectively. Conclusion: The sPPI, which is measured by professional hospice nurses, has acceptable validity to predict survival for patients with advanced cancer in a home hospice setting in South Korea.