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김선화,김해진,김준태,Kim, Sun-Hwa,Kim, Hae-Jin,Kim, Joon-Tae 대한환경위생공학회 2007 대한환경위생공학회지 Vol.22 No.1
This study was conducted the adsorption experiment way of organic wastewater (BOD, COD, TOC, T-N, T-P) by changing the carbonization temperature and the size of adsorbent to examine the adsorption capacity of Korean traditional charcoal which has similar characteristics to activated carbon of organic pollutants. Also, it was performed the basic experiment for pH and inorganic materials. As a result of observing Korean traditional charcoal with has the greatest inorganic contents which are the important factor of chemical adsorption. As the carbonization temperature was better high temperature charcoal than law temperature charcoal to adsorption capacity of pollutant and as the particle was minute (D size : $3.35mm{\sim}2.0mm$), it was most effective. The result of adsorption experiment of organic wastewater show that the elimination ratio of pollutants by bamboo high temperature charcoal was found as BOD(82.1%), COD(91.7%), TOC(52.4%), T-N(66.6%), T-P(83.2%) and it has most excellent adsorption capacity of organic pollutants.
퇴화처리(RRA)한 Al-Li 8090 합금의 미세조직에 관한 연구
김선화,이종권,Kim, Seon-Hwa,Lee, Jong-Gwon 한국재료학회 1995 한국재료학회지 Vol.5 No.5
Al 8090합금의 퇴화처리시에 나타나는 금속간화합물 변화과정과 PFZ 생성 및 입계석출물의 거동을 TEM을 사용하여 조사하였다. 기지에서는 $\delta$상, T$_{1}$ 상과 S'상이 모든 시편에서 관찰되었고, 입계어슨 PFZ이 형성되었다. 본 연구에 사용된 Al합금의 초기PFZ의 생성 기구는 입계의 임계공공 농도에 의한 것으로 나타났다. 2단계 열처리시 시간이 2분 이상이면 입계에 석축물이 형성되었다. 입계에는 중간단계로 5회전대칭축을 가지는 준안전상의 icosahedral상의 생성되었다. 평형 입계석출물은 사방정의 $Al_{13}$Fe$_{4}$였다.
2024 Al 합금의 ECAP 공정에 따른 미세조직 변화와 강도특성
김선화,최용락,Kim, Seon-Hwa,Choi, Yong-Lak 한국재료학회 2006 한국재료학회지 Vol.16 No.1
2024 Al alloys were severely deformed by equal channel angular pressing(ECAP) to obtain an ultrafine grain structure. The more deformation amount increased, the more grain size decreased. Most of the grain structure were changed from elongated to equiaxed shape with increasing pass number. The morphology of S' phases was also changed from rod-type to spherical type. The grain size of 6 passed specimen was 100 to 200 nm, and the size of S' phases was about 10 nm in the microstructure. XRD measurements have revealed that the texture formed by plastic deformation disappeared in the 6 passed specimen. SP test results described that the start of crack propagation occurred at the transition zone between plastic bending and membrane stretching because of small elongation. The maximum strength of ECA pressed specimen increased 1.9 GPa to 2.9 GPa with increasing pass number.
급랭응고한 Al-Fe-V-Si계 합금의 미세조직과 열안정성에 관한 연구
김선화,박원욱,Kim, Seon-Hwa,Park, Won-Wook 한국현미경학회 1991 Applied microscopy Vol.21 No.2
The main purpose of this paper was to investigate the change of rapidly solidified microstructures and dispersoid behavior according to heat-treatment in the Al-Fe-V-Si-(Mn) alloys. It was found that (111) preferred orientation identified by X-ray diffraction and fine subgrain/large grain were observed in the rapidly solidified Al-Fe-V-Si-(Mn) alloys. Cell boundary of the zone A was composed of the microcrystalline, whereas that of the zone B was amorphous. Decomposition of the Al-Fe-V-Si-(Mn) alloys occurred at about $300^{\circ}C$. These alloys exhibited excellent thermal stability at the elevated temperature. Microstructure of the zone B was more stable than that of the zone A. The spherical dispersoid and 5-fold symmetry phase was also more thermally stable than the amorphous structure of cell boundary.
NS-2를 이용한 MANET의 주소 자동설정 기법의 성능분석 연구
김선화,고빈,이규호,Kim, Sun-Hwa,Go, Bin,Lee, Kyou-Ho 한국시뮬레이션학회 2010 한국시뮬레이션학회 논문지 Vol.19 No.3
Simulation analysis may be the essential means to either evaluate performance of systems or optimize system parameters for new design. Including many variations for design and implementation, MANET (Mobile Ad-hoc NETwork) is one target area of such an analysis. Since every node, however, included in the network has mobility, one MANET could be overlapped or merged with another one which use a different transport protocol. In order to communicate among nodes in this case, the new merged network should configure paths and addresses in advance. Configuring paths and addresses generates much overheads which ultimately cause delay in communicating data. Performance analysis is required to improve the data transport performance by minimizing overheads. This paper proposes a sound address auto-configuration method which is based on an on-demand manner and then presents modeling and performance analysis of the method. NS-2 simulation results verify that the proposed method can not only alleviate overheads, which are inevitably generated for address auto-configuration processes, and but also decentralize them in time.
농작물 모니터링을 위한 점수기반 식생지수 합성기법의 개발
김선화,은정,Kim, Sun-Hwa,Eun, Jeong 대한원격탐사학회 2022 大韓遠隔探査學會誌 Vol.38 No.6
Clouds or shadows are the most problematic when monitoring crops using optical satellite images. To reduce this effect, a composite algorithm was used to select the maximum Normalized Difference Vegetation Index (NDVI) for a certain period. This Maximum NDVI Composite (MNC) method reduces the influence of clouds, but since only the maximum NDVI value is used for a certain period, it is difficult to show the phenomenon immediately when the NDVI decreases. As a way to maintain the spectral information of crop as much as possible while minimizing the influence of clouds, a Score-Based Composite (SBC) algorithm was proposed, which is a method of selecting the most suitable pixels by defining various environmental factors and assigning scores to them when compositing. In this study, the Sentinel-2A/B Level 2A reflectance image and cloud, shadow, Aerosol Optical Thickness(AOT), obtainging date, sensor zenith angle provided as additional information were used for the SBC algorithm. As a result of applying the SBC algorithm with a 15-day and a monthly period for Dangjin rice fields and Taebaek highland cabbage fields in 2021, the 15-day period composited data showed faster detailed changes in NDVI than the monthly composited results, except for the rainy season affected by clouds. In certain images, a spatially heterogeneous part is seen due to partial date-by-date differences in the composited NDVI image, which is considered to be due to the inaccuracy of the cloud and shadow information used. In the future, we plan to improve the accuracy of input information and perform quantitative comparison with MNC-based composite algorithm.
기관내 흡인 실시 후의 동맥혈 산소 분압 변화와 심부정맥 발현에 관한 연구
김선화,신정숙,최영희,Kim, Sun-Wha,Shin, Jung-Sook,Choi, Young-Hee 대한간호협회 1994 대한간호 Vol.33 No.4
The data were analyzed by using an S. P. S. S. computerized program for mean, standard deviation, percentage and paired t-test. The results of this study were as follows: 1. The increase in $PaO_2$ after hyperoxygenation and hyperinflation was highly statistically significant(p=0.041), and the increase in $PaO_2$ immediately after suctioning was not significant (p=0.752). The time of lowest $PaO_2$ was 30 seconds after the endotracheal suction. 2. The occurrance of cardiac arrhythmia after the endotracheal suction included sinus tachycardia, sinus arrhythmia, sinus bradycardia, premature atrial contraction (PAC), and premature ventricular contraction (PVC). The most frequent cardiac arrhythmia was sinus tachycardia (a subjects). Sinus arrhythmia was observed in 5 subjects and continued till 10 minutes after suctioning in two of these. Sinus bradycardia occurred in only 3 subjects and among them, 1 subjects shows sinus arrythmia till 10 minutes after suctioning along. PAC was observed in only one subject and continued till five minutes after suctining along with sinus arrhythmia. PVC was observed in three subjects: it lasted for only 30 seconds after suctioning in two subjects. but continued for 10 minutes after suctioning in the third. 6 subjects manifested two kinds of Cardiac arrhythmia Three of them showed sinus tachycardia with PVC, another 2 showed sinus bradycardia with sinus arrhythmia, and the other subject showed sinus arrhythmia with PAC. 3. The increases in heart rate during the endotracheal suction immediately after and at 30 seconds after suctioning were statistically significant (p=0.005). The increase in heart rate at one minute after suctioning was also significant (p=0.023). The increase in heart rate continued until 10 minutes after the endotracheal suction, but was not statistically significant In this study, endotracheal suctioning with hyperoxygenation and hyperinflation was effective in preventing a decrease in $PaO_2$ after suctioning, but not in preventing cardiac arrhythmias. Nurses should be aware of the complications of endotracheal suctioning and do effective hyperoxygenation and hyperinflation before and after suctioning. Further research is needed to develop a efficient endotracheal suction method which will minimize complications. This study needs to be replicated with different population of patients intubatted or having a tracheostomy, specifically, patients who cardiac or pulmonary desease. The data were analyzed by using an S. P. S. S. computerized program for mean, standard deviation, percentage and paired t-test. The results of this study were as follows: 1. The increase in $PaO_2$ after hyperoxygenation and hyperinflation was highly statistically significant(p=0.041), and the increase in $PaO_2$ immediately after suctioning was not significant (p=0.752). The time of lowest $PaO_2$ was 30 seconds after the endotracheal suction. 2. The occurrance of cardiac arrhythmia after the endotracheal suction included sinus tachycardia, sinus arrhythmia, sinus bradycardia, premature atrial contraction (PAC), and premature ventricular contraction (PVC). The most frequent cardiac arrhythmia was sinus tachycardia (a subjects). Sinus arrhythmia was observed in 5 subjects and continued till 10 minutes after suctioning in two of these. Sinus bradycardia occurred in only 3 subjects and among them, 1 subjects shows sinus arrythmia till 10 minutes after suctioning along. PAC was observed in only one subject and continued till five minutes after suctining along with sinus arrhythmia. PVC was observed in three subjects: it lasted for only 30 seconds after suctioning in two subjects. but continued for 10 minutes after suctioning in the third. 6 subjects manifested two kinds of Cardiac arrhythmia Three of them showed sinus tachycardia with PVC, another 2 showed sinus bradycardia with sinus arrhythmia, and the other subject showed sinus arr
김선화,Kim, Sun-Hwa 한국과학기술정보연구원 과학기술정보센터 1996 Journal of Information Science Theory and Practice Vol.27 No.3
1990년대에 만들어진 WWW는 하이퍼텍스트, 멀티미디어, GUI 등의 특성을 갖고서 급속도로 발전하여 현재는 인터넷의 대표적인 서비스로 자리를 잡았다. 이러한 특징을 갖는 WWW와 도서관의 OPAC을 인터페이스 시킴으로써 도서관과 이용자 양측 모두에게 유용한 검색용 도구가 되고있다. 본고에서는 먼저 WWW의 기본적인 특성 등에 대해 살펴본 후, WWW를 기반으로 한 도서관 온라인열람목록(OPAC)에 대하여 언급하고자 한다. 기존 텔넷(telnet)방식의 OPAC을 설명한 후, WWW를 기반으로 한 OPAC에 대해 비교적 상세히 언급하였다. 또한 도서관 OPAC과 WWW를 연동했을 때의 장단점에 대해서도 설명하였다. WWW having the characters of hypertext, multimedia, GUI, etc. has evolved as the leading service of Internet since the early 1990s. It's very useful to combine WWW echnologies and OPAC service in the aspects of users and library. This paper describes he overview of WWW and the Library OPAC services based on WWW. After comparing between Telnet and WWW, author will talk about the advantages and disadvantages of Library OPAC services based on WWW.
초고속 디지털 회로의 GBN 억제를 위한 육각형 EBG 구조의 전원면 설계
김선화,주성호,김동엽,이해영,Kim, Seon-Hwa,Joo, Sung-Ho,Kim, Dong-Yeop,Lee, Hai-Young 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.2
본 논문에서는 초고속 디지털 PCB 회로에서 발생하는 GBN(Ground Bounce Noise)을 억제하기 위한 새로운 EBG(Electromagnetic Bandgap) 구조의 전원면을 제안하였다. 제안된 구조는 육각형 모양의 단위 셀과 각 셀을 연결하는 선로로 구성되어 있다. 육각형 모양의 단위 셀은 등방성을 띄어 인접 셀의 각 포트 사이의 전달 특성을 동일하게 한다. 제안된 구조는 실제 제작, 측정되었고 330 MHz부터 5.6 GHz까지 넓은 주파수 대역에서 -30 dB 이하로 GBN을 억제하는 특성을 나타낸다. Electromagnetic Interference(EMI) 방사 측정 시에도 일반 전원면/접지면에 비해 낮은 EMI 특성을 나타낸다. 본 논문에서 제안한 육각형 EBG 구조의 전원면은 실제 EBG 전원면의 적용에 효율적으로 작용하여 초고속 디지털 회로의 EMI 문제를 해결하는 데 기여할 것으로 기대된다. In this paper, a novel hexagonal-shaped electromagnetic bandgap(EBG) power plane for the suppression of the ground bounce noise(GBN) in high-speed circuits is proposed. The proposed structure consists of hexagonal-shaped unit cells and detoured bridges connecting the unit cells. The hexagonal-shaped unit cells could omni-directionally suppress the GBN in digital circuits. The fabricated power plane's omni-directional -30 dB suppression bandwidth is from 330 MHz to 5.6 GHz. Then the proposed structure suppresses electromagnetic interference(EMI) caused by the GBN within the stopband. As a result, the proposed structure is expected to be conducive solving EMI problem in high-speed circuits.