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박종남,노승희,이동길 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.6
This study conducted a prototype development and evaluation by performing die-casting mold design, mold manufacturing, and injection condition optimization based on flow and solidification analysis to meet the needs of the coupling parts produced by die casting. Through flow analysis, the injection conditions suitable for 100% filling in the cavity were found to be a molten metal temperature of 670 ℃, injection speed of 1.164 m/s, and filling pressure of 6.324~18.77 MPa. In addition, solidification close to 100 % occurred in all four cavities when the solidification rate was 69.47 %. A defect inspection on the surface and inside the product revealed defects, such as poor molding and pores. In addition, the dimensions of the injected product were within the target tolerance and showed good results. Through the feedback of the results of flow and solidification analysis, it was possible to optimize the mold design, and the injection optimization conditions were confirmed to be a total cycle time of approximately 6.5 seconds. Good quality carrier parts with an average surface hardness of approximately 45 mm from the gate measured at 97.48(Hv) could be produced. 본 연구의 목적은 소비자 및 현장의 니즈에 부합하면서 다이캐스팅으로 생산할 수 있는 커플링 부품을 개발하고자 하였으며, 유동 및 응고해석을 기반으로 다이캐스팅 금형 설계, 제작, 및 사출조건 최적화 도출을 실시하였고 사출된 제품의 측정 및 평가를 수행하였다. 유동해석을 통하여 캐비티 내부가 100% 충진되기 위한 적정한 사출조건은 용탕의 온도 670℃, 사출속도 1.164m/s, 충진압력 6.324~18.77MPa로 분석되었다. 또한, 응고율이 69.47%일 때 4개의 캐비티 모두에서 100%에 근접하는 응고가 발생됨을 알 수 있었으며, 이를 기초로 시사출 조건설정 등에 응용하였으며 그 결과 사이클 타임은 약 6.5초로 도출되었다. 다이캐스팅으로 시사출된 제품의 표면 및 내부의 품질 검사를 수행한 결과 성형불량 및 기공 등의 결함은 전혀 발견되지 않았으며, 주요 개소의 치수를 측정한 결과 모든 항목에서 허용하는 공차 이내의 값을 보였다. 또한, 게이트로부터 약 45mm 이격된 곳의 평균 경도값은 97.7(Hv)로 나타나는 등 전체적으로 양호한 치수 및 품질의 부품을 제작할 수 있었다.
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박종남,노승희,이동길 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.11
Generally, end effectors for automatic robots can use ceramics such as alumina(Al2O3) and silicon carbide(SiC). In this study, black alumina was developed and used in the semiconductor field through powder molding press forming. The black alumina can be mass produced.Alumina and black alumina were ground using a plane grinder to apply to the end effector of an automatic robot. The optimal cutting conditionswere found by analyzing the surface roughness(Ra) of black alumina through grinding. The alumina surface roughness is the feed rate was about 0.72 mm/sec, and the number of revolutions was best at 0.4879 ㎛ at 1700 rpm. In addition, the black alumina surface roughness shows a precision of less than 0.2 ㎛ in most cutting conditions. The feed rate was about 0.72 mm/sec, and the number of revolutions was best at 0.1361 ㎛ at 1900 rpm. The surface roughness of black alumina was better than that of alumina by about 0.35 to 0.47 ㎛. 반도체 시장에서 소재 개발 및 제조 공법에 대한 연구는 꾸준히 진행되고 있다. 일반적으로 자동 로봇용 End Effector는 알루미나(Al2O3)와 탄화규소(SiC) 등의 세라믹이 사용되었다. 본 연구는 대량생산이 가능한 분말 성형 프레스 법을 통해 반도체 현장에서 사용되는 블랙 알루미나를 개발하였다. 그리고 알루미나와 블랙 알루미나를 자동 로봇의 End Effector에 적용될 수 있도록 평면 연삭기를 사용하여 연삭가공을 실시하였다. 연삭가공을 통해 블랙 알루미나 대한 표면 거칠기(Ra)를 비교 · 분석하여 최적의 절삭 조건을 확인 할 수 있었다. 알루미나 표면 거칠기는 이송 속도가 0.72 ㎜/sec이고 회전수가 1,700 rpm에서 0.4876 ㎛로 가장 양호하였다. 블랙 알루미나 표면 거칠기는 대부분의 절삭 조건에서 0.2 ㎛이하의 정밀도를 나타내었으며, 이송 속도가 0.72 ㎜/sec이고 회전수가 1,900 rpm에서 0.1364 ㎛로 가장 양호하였다. 블랙 알루미나의 표면 거칠기는 알루미나 보다 0.35 ㎛ ~ 0.47 ㎛ 정도 양호하였다.
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High performance quantum dot light emitting devices via surface engineering
박종남 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
InP quantum dots (QDs) are non-toxic emitters, which are considered an alternative to CdSe-based QDs. However, the limited choice and high cost of P precursors have a negative impact on their practical applicability. Here, we report the largescale synthesis of highly luminescent InP@ZnS QDs from an elemental P precursor (P<sub>4</sub>), which was simply synthesized via the sublimation of red P powder. In addition, all-inorganic perovskite quantum dots (PeQDs) based light-emitting devices (LEDs) was fabricated using CsPbX<sub>3</sub> QDs by a solid-state ligand exchange with aromatic acid/amine. The improvement in the overall photoemission efficiency of the resulting LED was confirmed under red, green, and blue conditions, demonstrating the luminance of 1889 cd/㎡ and a current efficiency of 6.28 cd/A was achieved.
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박종남 동아대학교 공과대학 부설 한국자원개발연구소 1990 硏究報告 Vol.14 No.1
Study was made on the characteristics of the Walsh power spectrum, particularly in terms of bias and variance of the estimate againt the true power spectrum, in order to provide basic infomations for geophysical data analysis. Random data for the analysis have been derived from an autoregression equation, Xi+1=a*Xi+Ni where a is a constant, indicating degrees of correlations beween neihboring data, and Ni the random noise. In this study, three different values of a, that is, a=-0.9, -0.5, and -0.1 are used for the autoregression. It is confirmed that the power spectra are much dependent upon the characteristics of the input data. In case of the input data which have high correlations between neighboring data, the optimum condition for the spectral analysis should be of the input being as long as possible. In this case it increases the sequential resolution as well. However, with low correlations between neighboring data, the input data should be divided into blocks as long as the sequential resolution is allowed. Obviously, the analysed results of each block should be averaged with an appropriate filtering.
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초음파 분석장비(UMQA4)를 이용한 파일의 건전도 시험을 위한 모형실험
박종남,이재경,김현건 동아대학교 건설기술연구소 1999 硏究報告 Vol.23 No.2
The ultrasonic logging method is one of the earliest methods of checking the integrity of pile. The main purpose of the paper is to conduct the model test in water to qualify the ultrasonic analyser, UMQA4, in its accuracy and repeatability and to offer basic information for effective analysis with the field data by model testing of the scaled concrete pile, and thus to increase the applicability of the apparatus. The result of experiment shows that the system is stable and excellent in repetition; and relatively easy and rapid in locating any defects in the pile in vertical section, but not in horizontal one, which should be studied further by tomography, etc. Also, further study on model-test should be done for its applicability to classifying near-surface rock mass features.
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