• Title/Summary/Keyword: S-63

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Effects of Solder Composition on Ball Fatigue Strength (솔더볼 피로강도에 대한 조성의 영향)

  • 김보성;고근우;김영철;김근식;이구홍
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2001.07a
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    • pp.127-133
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    • 2001
  • Package reliability test was conducted to investigate the effect of solder composition on ball fatigue strength. The specimens are first assembled using eutectic Composition S $n_{62}$P $b_{36}$A $g_2$, S $n_{63}$P $b_{34.5}$A $g_2$S $b_{0.5}$ solder and Pre-conditioned at MRT Lv 2a and then conducted under Temperature Cycle test(TC). For each case, the ball shear strength is obtained and micro structure photos are taken. SEM and EDX are used to analyze failure mechanism. The degradation of shear strength of solder balls after reliability test is discussed.d.

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Response surface methodology based multi-objective optimization of tuned mass damper for jacket supported offshore wind turbine

  • Rahman, Mohammad S.;Islam, Mohammad S.;Do, Jeongyun;Kim, Dookie
    • Structural Engineering and Mechanics
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    • v.63 no.3
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    • pp.303-315
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    • 2017
  • This paper presents a review on getting a Weighted Multi-Objective Optimization (WMO) of Tuned Mass Damper (TMD) parameters based on Response Surface Methodology (RSM) coupled central composite design and Weighted Desirability Function (WDF) to attenuate the earthquake vibration of a jacket supported Offshore Wind Turbine (OWT). To optimize the parameters (stiffness and damping coefficient) of damper, the frequency ratio and damping ratio were considered as a design variable and the top displacement and frequency response were considered as objective functions. The optimization has been carried out under only El Centro earthquake results and after obtained the optimal parameters, more two earthquakes (California and Northridge) has been performed to investigate the performance of optimal damper. The obtained results also compared with the different conventional TMD's designed by Den Hartog's, Sadek et al.'s and Warburton's method. From the results, it was found that the optimal TMD based on RSM shows better response than the conventional damper. It is concluded that the proposed response model offers an efficient approach regarding the TMD optimization.

Development of Age Classification Deep Learning Algorithm Using Korean Speech (한국어 음성을 이용한 연령 분류 딥러닝 알고리즘 기술 개발)

  • So, Soonwon;You, Sung Min;Kim, Joo Young;An, Hyun Jun;Cho, Baek Hwan;Yook, Sunhyun;Kim, In Young
    • Journal of Biomedical Engineering Research
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    • v.39 no.2
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    • pp.63-68
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    • 2018
  • In modern society, speech recognition technology is emerging as an important technology for identification in electronic commerce, forensics, law enforcement, and other systems. In this study, we aim to develop an age classification algorithm for extracting only MFCC(Mel Frequency Cepstral Coefficient) expressing the characteristics of speech in Korean and applying it to deep learning technology. The algorithm for extracting the 13th order MFCC from Korean data and constructing a data set, and using the artificial intelligence algorithm, deep artificial neural network, to classify males in their 20s, 30s, and 50s, and females in their 20s, 40s, and 50s. finally, our model confirmed the classification accuracy of 78.6% and 71.9% for males and females, respectively.

The Representation of Seong-An Streetscape in the 1960s' Cheongju (1960년대 청주 성안길 가로경관의 재현)

  • Kim, Tai-Young;Kim, Se Jin
    • Journal of the Korean Institute of Rural Architecture
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    • v.16 no.1
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    • pp.63-70
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    • 2014
  • This study is aimed to represent the streetscape in 1960s' focused on Seong-An street of Cheong-ju through the existing business types and buildings, literature, photo details, and interview of the longest-term householders. Results of this study are as follows : Firstly, the types of 1st-floor shops were diverse with general merchandise, apparel, medical, bank, restaurant, and etc in 1960s'. The present shops of them are 'Dong-kwang lasa', 'Jung-geum dang', 'Cheong-ju pharmacy' including the existing 'the Korea development', 'Korea first', and 'Woori' bank. Secondly, the streetscape around post office looks just as it did in the old 1960s'. In the other section the present typical buildings are 'Namseon pharmacy ', 'Kukje department', 'Samyang shop', 'Daeyang shop', 'Park shop', and etc. These old 3-4story buildings are reinforced concrete in contrasted with the former wooden and masonry in structure, and converted in use and appearance. Thirdly, the streetscape of Seong-An is ultimately represented by presuming the other buildings and equipments through aerial and street photograph in the old 1960s'.

A Study on the ADC for High Speed Data Conversion (고속 데이터 변환을 위한 ADC에 관한 연구)

  • Kim, Sun-Youb;Park, Hyoung-Keun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.3
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    • pp.460-465
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    • 2007
  • In this paper, the pipelined A/D converter with multi S/H stage structure is proposed for high resolution and high-speed data conversion rate. In order to improve a resolution and operational speed, the proposed structure increased the sampling time that is sampled input signal. In order to verify the operation characteristics 20MS/s pipelined A/D converter is designed with two S/H stage. The simulation result shows that INL and DNL are $0.52LSB{\sim}-0.63LSB$ and $0.53LSB{\sim}-0.56LSB$, respectively. Also, the designed Analog-to-Digital converter has the SNR of 43dB and power consumption is 18.5mW.

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Comparison of the basic Aerodynamics between the World Cup Official Ball and Korean Soccer Balls (월드컵 공인구와 한국 축구 공인구 사이의 기초 공력특성 비교)

  • Sungchan Hong
    • Korean Journal of Applied Biomechanics
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    • v.34 no.2
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    • pp.63-70
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    • 2024
  • Objective: This study aims to compare the basic aerodynamic characteristics of the official Qatar World Cup soccer ball with those of the official Korean soccer balls. Method: In this study, wind tunnel experiments were conducted to compare the fundamental aerodynamic properties of two commonly used domestic soccer balls, the Star and Nassau, with the Al Rihla, the official ball of the 2022 Qatar World Cup. Results: The findings revealed that the Nassau soccer ball exhibited changes in aerodynamic characteristics depending on its orientation, particularly at low speeds (below 15 m/s), while the Al Rihla showed variations in aerodynamic characteristics at medium to high speeds (15 m/s to 35 m/s) based on its orientation. Furthermore, the results of lift and side force variations indicated that the Star soccer ball exhibited larger changes compared to other soccer balls, suggesting that it may exhibit the most irregular flight path during strong shots (around 30 m/s or approximately 100 km/h). However, there were no differences in aerodynamics observed among the soccer balls in the medium-speed range (20~25 m/s). Conclusion: The comparison of aerodynamics between the Korean soccer balls and the most recently used World Cup official ball showed that, while the Korean balls exhibited slightly greater changes in lift and side forces compared to the World Cup ball, there were no significant differences in most of the aerodynamic characteristics.

A multi-wavelength study of N63A: A SNR within an H II region in the LMC.

  • Aliste C., Rommy L.S.E.;Koo, Bon-Chul;Lee, Yong-Hyun
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.1
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    • pp.54.3-55
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    • 2017
  • The nature and physical environments of SNRs are diverse, and for this reason, the understanding of the properties of nearby SNRs is useful in interpreting the emission from SNRs in remote galaxies where we cannot resolve them. In this regard, the LMC is a unique place to study SNRs due to its proximity, location, and composition compared with our galaxy. We carried out a multi-wavelength study of SNR N63A in the LMC, a young remnant of the SN explosion of one of the most massive (> 40 Msun) stars in a cluster. It is currently expanding within a large H II region formed by OB stars in the cluster and engulfing a molecular cloud (MC). As such, N63A is a prototypical SNR showing the impact of SN explosion on the cluster and its environment. Its morphology varies strongly across the wave bands, e.g. the size in X-ray is three times larger than in optical. However, the bright optical nebula would correspond to a MC swept up by the SNR, and consequently the interaction SNR-MC is limited to the central portion of the SNR. We aimed to study the overall structure of N63A, using near-IR imaging and spectroscopic observations to obtain the physical parameters of the atomic shocks, and also to understand how the SNR- MC interaction works and reveal the structure of the shocked cloud as well as the consequences of the impact of the SNR shock on the MC, comparing information obtained in different wavelengths.

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The role of natural rock filler in optimizing the radiation protection capacity of the intermediate-level radioactive waste containers

  • Tashlykov, O.L.;Alqahtani, M.S.;Mahmoud, K.A.
    • Nuclear Engineering and Technology
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    • v.54 no.10
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    • pp.3849-3854
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    • 2022
  • The present work aims to optimize the radiation protection efficiency for ion-selective containers used in the liquid treatment for the nuclear power plant (NPP) cooling cycle. Some naturally occurring rocks were examined as filler materials to reduce absorbed dose and equivalent dos received from the radioactive waste container. Thus, the absorbed dose and equivalent dose were simulated at a distance of 1 m from the surface of the radioactive waste container using the Monte Carlo simulation. Both absorbed dose and equivalent dose rate are reduced by raising the filler thickness. The total absorbed dose is reduced from 7.66E-20 to 1.03E-20 Gy, and the equivalent dose is rate reduced from 183.81 to 24.63 µSv/h, raising the filler thickness between 0 and 17 cm, respectively. Also, the filler type significantly affects the equivalent dose rate, where the redorded equivalent dose rates are 24.63, 24.08, 27.63, 33.80, and 36.08 µSv/h for natural rocks basalt-1, basalt-2, basalt-sill, limestone, and rhyolite, respectively. The mentioned results show that the natural rocks, especially a thicker thickness (i.e., 17 cm thickness) of natural rocks basalt-1 and basalt-2, significantly reduce the gamma emissions from the radioactive wastes inside the modified container. Moreover, using an outer cementation concrete wall of 15 cm causes an additional decrease in the equivalent dose rate received from the container where the equivalent dose rate dropped to 6.63 µSv/h.

A Theoretical Study on the Radionuclide Transport Mediated by Pseudo-Colloid in the Fractured Rock Medium (균열 암반 매질에서 의사콜로이드에 의해 매개된 방사성 핵종의 이동에 대한 이론적 연구)

  • Baik, M.H.;Hahn, P.S.;Park, H.H.
    • Nuclear Engineering and Technology
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    • v.27 no.4
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    • pp.532-543
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    • 1995
  • In this study, a transport model was developed in order to analyze and predict the transport behaviors of radionuclides mediated by pseudo-colloid in the fractured rock media. The effect of pseudo-colloid formation on the transport of a radionuclide was shown to be tory significant when an ap-parent pseudo-colloid formation constant, $A_{ap}$ (㎥/kg), os greater than 100. It was resulted from example calculations that the transport of Pu-239 was faster than Ni-63 because pseudo-colloid formation constant of Pu-239 was venter than that of Ni-63. Thus, it can be concluded that acceleration of radionuclide migration may be occurred because the pseudo-colloid formation of radionuclides increases the amount of mobile components in the solution and consequently decreases the amount of radionuclides adsorbed on the stationary solid medium.

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General characters and applications of photosynthetic bacteria (광합성세균의 생리 및 이용에 관한 최근의 동향)

  • 이광웅
    • Korean Journal of Microbiology
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    • v.9 no.3
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    • pp.130-138
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    • 1971
  • In order to investigate the production of aflatoxin in various conditions such as pH, moisture and temperature, 27 smaples were inoculated with Aspergillus flavus, and in addition 3 smaples were inoculated with the mixture of Aspergillus flavus and Bacillus subtilis and cultured under the conditions such as 20.deg.C and 30% moisture contents. The following results were obtained : 1) Aflatoxin production was the highest at pH 5.0 and relatively high at pH 7.0. Its production was decreased significantly when pH reached 9.0. 2) The yield of aflatoxin was shown comparatively high level at 30% moisture contens. The higher moisture contents was, the lower aflatoxin production was. 3) The highest level of aflatoxin production was at 20.deg,C, and comparatively high level was at 30.deg.C. However, its production was fairly low at 40.deg.C. 4) The highest crude aflatoxin production was 5,093ppm (B$_{1}$, 1.912ppm ; B$_{2}$, and the lowest one 2.197 ppm (B$_{1}$, 0.793 ppm : B$_{2}$, 0.185 ppm : G$_{1}$ ,0.102 ppm G$_{2}$, 0.381ppm) at 63% moisture, pH 9.0 and 40.deg.C. 5) When Aspergillus flavus and Bacillus subilis were cultured together under the conditions such as 20.deg.C and 30% moisture, aflatoxin production was decreased by 27% comparing with the culture of Aspergillus flavus alone.

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