• Journal of Welding and Joining
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• 제20권6호
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• pp.78-78
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• Journal of Welding and Joining
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• 제20권6호
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• pp.802-808
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• 공업화학
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• 제26권2호
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• pp.224-228
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• 2015

나프타 분해공정에서 부산물로 발생하는 분해연료오일을 이용하여 열처리 및 UV 조사 시 다양한 농도의 $AlCl_3$을 첨가하여 새로운 방법으로 탄소전구체 피치를 제조하였다. 개질된 피치는 원소 분석, 화학 구조, 분자량 분포 및 연화점을 분석하여 특성평가를 하였다. 개질된 피치의 산소 함량은 $AlCl_3$의 첨가량이 증가할수록 증가한 반면 그 탄소 및 수소 함량은 거의 변화하지 않았다. UV 조사 개질피치는 열 개질만 된 피치보다 더 많은 방향족 탄소화합물로 이루어져 있었다. $AlCl_3$ 촉매첨가는 개질된 피치의 방향족화도에 큰 영향을 미치지 않았다. 제조된 피치의 연화점은 $103.3{\sim}168.9^{\circ}C$ 범위를 나타내었다. 또한 5 wt%의 $AlCl_3$를 첨가하여 UV 조사 개질된 피치의 수율은 48%에서 80%로 증가하였다. 이것을 통하여 UV 조사 개질 방법은 다양한 특성을 갖는 고수율의 피치를 제조를 위한 실용적이고 유용한 방법으로 여겨진다.

• 공업화학
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• 제28권5호
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• pp.534-538
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• 2017

본 연구에서는 PFO (pyrolyzed fuel oil)의 개질을 통해 탄소전구체(피치)를 제조한 후, 유기용매를 통한 분자량 조절을 하고 탄화하여 음극소재를 제조하였다. 리튬이차전지 음극소재의 전기화학적 특성은 석유계 피치를 사용하여 조사되었다. 사용된 세 종류의 피치는 3903, 4001, 4002이며, 각 PFO를 $390^{\circ}C$ 3 h, $400^{\circ}C$ 1 h, $400^{\circ}C$ 2 h 열처리 하여 제조하였다. 제조된 헥산 불용성 피치의 물리적 특성은 XRD, TGA, GPC, SEM으로 분석되었다. 음극소재로서의 피치의 전기화학적 특성은 충 방전, 순환전압전류, 임피던스, 속도 테스트를 통해 조사되었다. 4001 피치를 통하여 제조된 음극소재와 $LiPF_6$ (EC : DMC = 1 : 1 vol%, VC 3 wt%)를 사용하여 제조한 반쪽 전지는 향상된 초기용량(310 mAh/g)을 보였으며, 초기 효율(82%), 2 C/0.1 C 속도특성(90%), 용량 유지율 85%의 특성을 보였다. 본 연구에서 제조된 피치는 사이클 특성과 속도특성이 향상됨을 알 수 있었다.

• 말소리와 음성과학
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• 제1권4호
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• pp.187-193
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• 2009

For this study, the external laryngeal lengths of 9 females and 9 males with normal voices were measured together with their ages, heights, and weights, and after they read aloud sentences for 3 minutes, their habitual speaking fundamental frequencies, speaking low pitches, speaking high pitches, and vocal fold closed quotients were measured. The Spearman rank correlation analysis on these data showed a significant negative correlation between the external laryngeal length and the habitual speaking fundamental frequency for both females and males, a significant negative correlation between the external laryngeal length and the speaking high pitch for only males, a significant negative correlation between the external laryngeal length and the speaking low pitch for both females and males, and a significant positive correlation between the external laryngeal length and the vocal fold closed quotient for only males.

• Carbon letters
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• 제12권2호
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• pp.70-80
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• 2011

Two pitches with different average molecular structures were electrospun and compared in terms of the properties of their fibers after oxidative stabilization, carbonization, and activation. The precursor with a higher molecular weight and greater content of aliphatic groups (Pitch A) resulted in better solubility and spinnability compared to that with a lower molecular weight and lower aliphatic group content (Pitch B). The electrical conductivity of the carbon fiber web from Pitch A of 67 S/cm was higher than that from Pitch B of 52 S/cm. The carbon fiber web based on Pitch A was activated more readily with lower activation energy, resulting in a higher specific surface area compared to the carbon fiber based on Pitch B (Pitch A, 2053 $m^2/g$; Pitch B, 1374 $m^2/g$).

• 음성과학
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• 제15권3호
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• pp.175-181
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• 2008

The aim of this study was to survey 'voice preference' of children from among three voice pitches, which are high-pitch, mid-pitch and low pitch, and understand acoustic characteristics of the best voice chosen. To record distinctive pitches, Dr. Speech(ver. 4.0 Tiger Electronics) was used and we analyzed their choices. Also, we measured subglottal air pressure in aerodynamic analyze and phonatory aerodynamic system(Model 6600, KAY) was used. As a result children preferred to the low-pitch yet there was not any difference by sex. We fined them to prefer higher HNR voice to lower jitter and shimmer voice rate.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1995년도 제12회 음성통신 및 신호처리 워크샵 논문집 (SCAS 12권 1호)
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• pp.221-224
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• 1995

In speech signal processing, it is necessary to detect exactly the pitch. The algorithms of pitch extraction with have been proposed until now are difficult to detect pitches over wide range speech signals. In this paper, thus, we proposed a new pitch detection algorithm that used a low pass filter with variable bandwidth. It is the method that preprosses to find the first formant of speech signals by the FFT at each frame and detects the pitches for signals LPFed with the cut off frequency according to the first formant. Applying the method, we obtained the pitch contours, improving the accuracy of pitch detection in some noise environments.

• 한국멀티미디어학회논문지
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• 제20권9호
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• pp.1502-1508
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• 2017

A musical key is a fundamental concept in Western music theory. It is a collective characterization of pitches and chords that together create a musical perception of the entire piece. It is based on a group of pitches in a scale with which a music is constructed. Each key specifies the set of seven primary chromatic notes that are used out of the twelve possible notes. This paper presents a method that identifies the key of a song using Hidden Markov Models given a sequence of chroma features. Given an input song, a sequence of chroma features are computed. It is then classified into one of the 24 keys using a discrete Hidden Markov Models. The proposed method can help musicians and disc-jockeys in mixing a segment of tracks to create a medley. When tested on 120 songs, the success rate of the music key identification reached around 87.5%.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.541-546
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• 2009

There are many videos about sports. There is a large need for content based video retrievals. In sports videos, the motions and camera works have much information about shots and plays. This paper proposes the baseball game process understanding using the similar motion retrieval on videos. We can retrieve the similar motion parts based on motions shown in videos using the space-time images describing the motions. Using a finite state model of plays, we can decide the precise point of pitches from the pattern of estimated typical motions. From only the motions, we can decide the precise point of pitches. This paper describes the method and the experimental results.