• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.4
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• pp.356-362
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• 1994

We developed a computer controlled Czochralski puller which automated entire crystal growing processes. Crystal weighing technique was employed for an automatic diameter control. The performance of the system was evaluated by the growth of $LiNbO_3$ single crystals.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.319.1-319
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• 2002

A frequency-domain PES estimation and its prediction method are proposed for the tightly-coupled servo/mechanical design of high-TPI HDD system above 100kTPI. The major two disturbance energies which are related with mechanical vibrations inside of HDD are used to predict the drive-level PES, while considering closed-loop servo dynamics. One is the torque disturbance which mainly comes from aerodynamic excitation of HSA system and the other is the displacement disturbance from disk-spindle dynamics. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.320.2-320
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• 2002

In high-capacity disk drives with ever-growing track density, the allowable level of position error signal (PES) is becoming smaller and smaller. A substantial portion of the PES is caused by disk vibration. This can be reduced by using a head gimbal assemblies (HGAs) that do not confine the slider movement to the vertical direction to disks, but allow movement to the radial direction of disks with respect to disk vibration. Several types of HGAs are proposed for such radial motion of the slider. (omitted)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.76-82
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• 1994

Single crystals of Potassium Titanyl Phosphate (KTP) were grown from the flux of $K_6P_4O_13(K_6)$ using a high temperatures solution growth method. To grow the large KTP crystal without inclusion, the temperature gradient in furnace, crystal rotation, orientation of seed crystal, and the cooling rate were controled. The KTP crystals are up to $10(a){\times}28(b){\times}33(c)mm^3$ in size. We investigated the optical inhomogeneity in this KTP crystal by the SHG power measurement and TEM analysis.

• Phonetics and Speech Sciences
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• v.16 no.2
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• pp.37-47
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• 2024

This study was conducted on 27 male students majoring in or preparing for popular music vocals to determine whether they were aware of their voice classification and vocal range. Additionally, differences in the fundamental frequency and average speaking fundamental frequency were compared among the voice classifications. Moreover, considering that they may differ in their ability to produce high frequencies depending on the vowel, differences in voice ranges among the cardinal vowels, /a/, /i/, and /u/, were examined, and differences in voice ranges between vowels were compared by voice classification. The results showed that more than half of the male students majoring in or preparing for popular music vocals were not accurately aware of their voice types. In addition, statistically significant differences were found in the maximum fundamental frequency and frequency range among vowels, indicating differences in the voice range that can be produced depending on the vowel type. In particular, the voice range decreased in the following order: /a/>/u/>/i/. This suggests that while the vowel /a/ is easier to articulate in the high register compared to other vowels, vowels /u/ and /i/ as high vowels involve narrowing of the oral cavity due to the raised position of the tongue, accompanied by raising of the larynx, resulting in a decrease in voice range and difficulty in vocalizing in the high register.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.339.2-339
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• 2002

In recent years, the demand of mobile device, such as digital camera, camcoder and PDA, increases remarkably. So, requirements of the mobile information data storage used in the mobile devices increase noticeably also. 1" micro storage is a kind of mobile storage, which has a CF type II form factor, and the similar structure of the general 3.5" HDD. In this paper, we performed the vibration analysis and experimental study of disk-spindle system in 1 " micro storage, such as measurement of the NRRO of the disk, and modal analysis. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.340.2-340
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• 2002

A practical implementation method of squeeze-film aeroelastic disk vibration damping and its practical design performance are presented to provide a solution method to meet the tight TMR(Track Mis-Registration) design budget of high-TPI HDDs. Most previous research results are mainly based on the component-level study in the 'open-cover state' which is far from the realistic operations HDD condition. (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.245-252
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• 1990

The distributions of copepods and chaetognaths in waters off the southern coast of Korea were investigated to evaluate their reliability as indicator species of different water masses. The samples for this study were collected vertically from about 5m above the bottom at 28 stations along 8 transects in three different months, February, April, and August, 1988. The sampling gear used was 0.45-meter NORPAC plankton net fitted with 0.33mm mesh. Acartia clausi, Centropages abdominalis, and Sagitta crassa were found to be reliable indicator species of neritic cold waters; Pleuromamma gracilis, Undinula darwini, Calocalanus plumulosus, Calanopia elliptica, and Sagitta enflata were of oceanic warm waters; Temora discaudata and Centropages furcatus were of neritic warm waters. According to the cluster analyses of the species found, the distinctive area in February was divisible into two regions or water masses, the coastal and off-shore regions; in April, however, it was divisible into four regions. In August, it was divisible into three areas, further indicating the strength of the Kuroshio tributaries pushing toward the coast.

• The Science & Technology
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• v.35 no.5 s.396
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• pp.40-42
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• 2002

북한에서 최고의 교육전당이라고 불리는 김일성종합대학은 최근 자연과학 분야의 컴퓨터 분야에 역점을 두고 있으며 공과대학으로 최고의 위치를 자랑하는 김책공업종합대학은 1948년 김일성종합대학에서 분리되어 현재 19개 학부에 71개 학과가 설치되어 있다. 그밖에 평양기계대학 등 단과대학에서도 과학기술자들을 양성하고 있다.

• The Science & Technology
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• v.35 no.7 s.398
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• pp.32-33
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• 2002

삼성종합기술원 최원봉박사팀은 과제를 시작한지 1년도 안돼 나노튜브를 선택 성장하고 직격을 조절하는 기술을 개발했으며 트랜지스터 작동이 됨을 확인했다. 이 결과는 세계 최초의 탄소 나노튜브 위치제어 및 수직 트랜지스터 기술개발로 인정받았다.