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TDMA 네트워크 전술데이터링크 송수신기 구현 및 성능고찰
남정호,서난솔,장동운,Nam, Jeong-Ho,Seo, Nan-Sol,Jang, Dhong-Woon 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.3
Generally, flight information is transmitted by voice signal over legacy UHF radio in ground to air communication system. In this paper, we have implemented the transceiver of TDL(tactical data link) which transmits tactical information, such as flight information, using digital signal. For transmitting digital information over radio path, we have designed data modem that is processing CPFSK modulation, and TDMA(Time Division Multiple Access) network for Synchronization among multi user(platform). By simulating aeronautical propagation modeling with the environment of Korea terrain, it is predicted the maximum performance of communication range of the transceiver. As result of the transceiver's aviational boarding test, it is proved that the transceiver of TDL over legacy UHF radio transmits and receives the tactical information in TDMA network within communication range of 160km.
Projection Method에 의한 주조 해석용 접촉 요소망 생성 기법
남정호 ( Jeong-ho Nam ),곽시영 ( Si-young Kwak ) 한국주조공학회 2020 한국주조공학회지 Vol.40 No.6
In general, hot metal castings contract and molds expand during the cooling step of a casting process. Therefore, it is important to consider both the casting and mold at the same time in a casting process analysis. For a more accurate analysis that includes the contact characteristics, matching each node of the casting and mold in the contact area is recommended. However, it is very difficult to match the nodes of the casting and the mold when generating elements due to the geometric problem of CAD model data. The present study proposes a mesh generation technique that considers mechanical contact between the casting and the mold in a casting analysis (finite element analysis). The technique focuses on the fact that the mold surrounds the casting. After generating the 3D elements for the casting, the surface elements of the casting in contact with the mold are projected inside the mold to create contact elements that coincide with the contact surface of the casting. It was confirmed that high-quality contact element information and a 3D element net can be automatically generated by the method proposed in this study.
Jun-Ho Hong(홍준호),Jeong Ho Nam(남정호),Young-Sim Choi(최영심),Ho-Young Hwang(황호영) (사)한국CDE학회 2013 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2013 No.1
HPDC(high pressure die casting) process is one of the most economic casting process for light-weight materials such as aluminum alloy, and an effective way which can make castings by the injection of molten metal into the permanent mould during very short time. This method has some benefits such as obtaining fine casting surface and increasing production speed. This process, however, has a problem that the defects appear easily. The defects are occurred mainly due to the injection speed control, open-close time control of die, mold filling pattern control, lubricant spray time and position control etc. Many researchers have done and reported about the optimization of casting system. But, almost of all researches are only about the optimization of casting system, position change of overflow. The optimization about the whole processes is necessary because the defects are concerned with many processes in HPDC. In this research, the virtual reality system of whole processes of HPDC will be developed to make the reducing the defects of castings during the optimization of processes in HPDC.
한국형 고속전철 객차 연결부 에어백 지지부 대형 알루미늄 주물의 개발
유승목(Yoo Seung-Mok),남정호(Nam Jeong-Ho),김정인(Kim Jeong-In),임채호(Lim Chae-Ho),김용현(Kim Young-Hyun),박수현(Park Soo-Hyun) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-
For the lighting of vehicles structural casting components of aluminum casting alloys are substituted for those of steel or iron. For the manufacturing of large-scale premium quality aluminum castings the developments of a new casting process and a heat treatment process are necessary. The optimum casting design and heat treatment condition for large-scale castings are drawn with the help of Z-Cast software for the casting process analysis in this study. Low pressure sand casting method is applied successfully to produce air bag support components of D357 aluminum casting alloy.
Smoothed Particle Hydrodynamics (SPH) 를 이용한 유동 시뮬레이션 연구
송재경(Jaekyung Song),남정호(Jeong Ho Nam),임채호(Chae Ho Lim) (사)한국CDE학회 2015 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2015 No.하계
Grid-based method such as Finite Difference Method(FDM), Finite Volume Method(FVM) have been mainly used for flow simulation. Furthermore, particle-based method (Smoothed Particle Hydrodynamics(SPH), Moving Particle Semi-Implicit(MPS) and Discrete Element Method(DEM) etc.) is recently being treated by many researchers. Particle-based methods were introduced long ago but it has not studied enough because there were some problems like as expensive run-time. However, it is currently being applied in various engineering fields because of highly enhanced hardware performance and many parallel techniques (OpenMP, CUDA, OpenCL, etc.). In this paper, we implement the flow simulation using GPU-based(CUDA) SPH and we show simulation results by using SPH compared with the experiment and by using FDM.
정경한(Gyeong Han Jeong),정윤희(Yun Hee Jeong),남정호(Jung Ho Nam),김태훈(Tae Hoon Kim) 한국식품영양과학회 2020 한국식품영양과학회지 Vol.49 No.8
들깨박의 열수 추출물의 EtOAc 가용부는 DPPH 및 ABTS⁺ 라디칼을 활용한 라디칼 소거능 평가에서 IC50값이 각각 167.5±1.8, 28.0±1.1 ㎍/mL로 우수한 라디칼 소거 활성을 나타냄을 확인하였다. 활성성분 동정을 위하여 EtOAc 분획물에 대해 반복적인 컬럼크로마토그래피를 활용하여 활성물질의 분리 및 정제를 수행하여 10종의 페놀성 화합물을 분리하였고, 각 화합물의 구조는 NMR, FABMS 스펙트럼 해석 및 표품과의 HPLC 직접 비교를 통하여 rosmarinic acid 3-O-glucoside(1), rosamrinic acid(2), caffeic acid(3), p-coumaric acid(4), vanillic acid(5), vanillin(6), protocatechuic acid(7), protocatechuic aldehyde(8), phydroxybenzoic acid(9) 및 p-hydroxybenzaldehyde(10)로 동정하였다. 분리된 화합물에 대해 라디칼 소거 활성을 평가한 결과, romarinic acid(2)가 DPPH 및 ABTS⁺ 라디칼에 대해 가장 우수한 라디칼 소거 활성(IC50=34.1±0.8, 20.6±1.0 μM)을 나타냄을 확인하였으며, 또한 caffeic acid(3)는 DPPH 및 ABTS⁺ 라디칼에 대해 IC50값이 각각 82.7±1.8, 41.4±1.6 μM의 라디칼 소거능을 확인하였다. 들기름 착유 후의 들깨박에는 우수한 라디칼 소거능을 나타내는 다량의 페놀성 화합물이 함유되어 있는 것을 확인하였으며, 향후 세포 및 동물을 활용한 연구를 통하여 기능성 소재로서의 추가 검증이 필요하다고 생각된다. The antioxidant capacity of the hot water extract of defatted Perilla cake were evaluated using DPPH and ABTS⁺ radical scavenging assays. The extracts of four solvent fractions (n-hexane layer, EtOAc layer, n-BuOH layer, and residue) of the hot water extract were also investigated. In particular, the radical scavenging activity of the EtOAc-soluble portion from defatted Perilla cake was higher than those of the other solvent-soluble layers. This paper reports the chromatographic isolation and characterization of ten phenolic constituents of previously known structures, rosmarinic acid 3-O-glucoside (1), rosmarinic acid (2), caffeic acid (3), p-coumaric acid (4), vanillic acid (5), vanillin (6), protocatechuic acid (7), protocatechuic aldehyde (8), p-hydroxybenzoic acid (9), and p-hydroxybenzaldehyde (10). The chemical structures of these isolated compounds were identified by neclear magnetic resonance (NMR) spectroscopy and mass spectrometry methods. Among the compounds tested, rosmarinic acid (2) and protocatechuic aldehyde (8) showed the most potent DPPH radical scavenging activities with IC50 values of 34.1±0.8 and 74.2±1.2 μM, respectively. In addition, these two compounds showed significant ABTS⁺ radical scavenging capacities. These results suggest that the radical scavenging activities of defatted Perilla cake are closely correlated with the presence of phenolic compounds.