• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1065-1071
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• 2012

Wind energy is becoming one of the most preferable alternatives to conventional sources of electric power that rely on fossil fuels. For stable electric power generation, constant rotating speed control of a wind turbine is performed through pitch control and stall control of the turbine blades. Recently, variable pitch control has been implemented in modern wind turbines to harvest more energy at variable wind speeds that are even lower than the rated one. Although wind turbine pitch controllers are currently optimized using a step response via the Ziegler-Nichols auto-tuning process, this approach does not satisfy the requirements of variable pitch control. In this study, the variable pitch controller was optimized by a genetic algorithm using a neural network model that was constructed by the Latin Hypercube sampling method to improve the Ziegler-Nichols auto-tuning process. The optimized solution shows that the root mean square error, rise time, and settle time are respectively improved by more than 7.64%, 15.8%, and 15.3% compared with the corresponding initial solutions obtained by the Ziegler-Nichols auto-tuning process.

• Composites Research
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• v.29 no.5
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• pp.256-261
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• 2016

In this work, we have prepared the filter papers with the pitch-based activated carbon fibers and the binder fibers using wet-laid process. The influence of the binder fiber on the porosity of the filter papers has been investigated by using nitrogen adsorption isotherms at 77 K and a scanning electron microscope (SEM). As a result, the specific surface area has increased with an decrease in the content of binder fiber. It has been shown that the optimum ratio of pitch-based activated carbon fibers and the binder fibers is 70:30, resulting in high porosity, excellent bonding strength, large specific surface area ($650.4m^2/g$) and high noxious gas removal efficiency (86.9%). In addition, it has been observed that the mean pore size distribution of the fiber papers has not been affected by the binder fiber.

• Phonetics and Speech Sciences
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• v.11 no.4
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• pp.9-18
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• 2019

This study aimed to investigate the correlation between speaker's chronological age (CA) and perceived age (PA) and to specify the effect of pitch and speech rate as acoustic cue on judging age, using perceptual testing and acoustic analysis. Three tasks were conducted to identify the degree of listener's accuracy about age estimation. Three perception tasks were conducted to measure the accuracy of 80 Korean listeners when presented with different types of speech. In all the tasks, participants listened to speech samples and gave their estimate of the speaker's age in figures. It was found that Korean listeners are able to gauge the age of a speaker fairly precisely. CA and mean PA were positively correlated in all three tasks. It is clear that the amount and type of information included in the voice samples affected the accuracy of a listener's judgement. Moreover, the result revealed that listeners make use of acoustic information such as pitch and speech rate to estimate speaker's age.

• Journal of Korean Society of Forest Science
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• v.17 no.1
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• pp.23-28
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• 1973

In this survey, to estimate volume growth of pitch pine (Pinus rigida Mill) stand, diameter growth was estimated. Among 223 sample trees, the number of rejected trees was 12, about 5 percent of total sample trees. The stand showed uniform growth and rejected trees included insect-damaged trees. Compared with reports made on forest classification basis, pitch pine a single species showed faster growth. Minimum, average and maximum value of D.B.H and mean annual diameter growth, of 16 year old pitch pine stand, were as follow. The correlation of each factors estimated by 9590 of confidence interval is shown in the table of correlation as bellow.

• Journal of Ocean Engineering and Technology
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• v.31 no.2
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• pp.81-90
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• 2017

The 1MW OTEC (Ocean Thermal Energy Conversion) platform was designed for application in equatorial seas. In this study, the OTEC platform was investigated using numerical and experimental methods. An octagon-shaped OTEC platform was investigated using the Ocean Engineering Basin of KRISO. These experiments included various tests of regular waves, irregular waves and irregular waves with current (wave+current). The responses of the platform in regular waves showed good agreement between the numerical and experimental results, including the motion RAO, wave run up, and mean drift force. The peak period of heave and pitch motions were observed around 0.5 rad/s, and the effect of the total reflection was found under short wave conditions. The standard deviation (STD) of the platform motion was checked in irregular waves of equatorial and Hawaiian seas. The STD of the pitch was less than $4^{\circ}$ different from the operability requirement under equatorial conditions and the surge STD of the wave frequency showed good agreement between the numerical and experimental results. The STD values of the surge and pitch were increased 66.6% and 92.8% by the current effects in irregular waves, but the pitch STD was less than $4^{\circ}$ under equatorial conditions. This study showed that the STD of the surge was affected by spring effects. Thus, the watch circle of the platform and tension of the mooring lines must be evaluated for a specific design in the future.

• Journal of Korean Foot and Ankle Society
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• v.22 no.1
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• pp.16-20
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• 2018

Purpose: To evaluate the clinical and radiographic results of surgical treatment for patients with sinus tarsi pain due to accessory talar facet impingement. Materials and Methods: Between July 2013 and July 2015, nine patients who underwent surgery for the accessory talar facet impingement were reviewed. The mean follow-up period was 18.6 months (12~36 months), and the mean age was 33.1 years (19~60 years). Previous trauma history, duration of symptom, and types of surgery were analyzed. The clinical results were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and visual analogue scale (VAS). Radiographic results were assessed using Meary's angle, calcaneal pitch angle, heel alignment angle, and heel alignment ratio. Results: All patients had evident trauma history prior to the initial symptom. The mean duration of symptoms was 25.6 months (6~120 months). Four patients received only accessory anterolateral talar facet (AALTF) excision, and four patients received medial sliding calcaneal osteotomy (MSCO). One patient underwent both AALTF excision and MSCO. The AOFAS ankle-hindfoot score was significantly improved from 73 (62~77) preoperatively to 93 (67~100) postoperatively. The VAS score was decreased from 6 (5~7) preoperatively to 1 (0~5) postoperatively. The Meary's angle and calcaneal pitch angle showed no significant difference after surgery. The heel alignment angle and ratio increased from $-3.6^{\circ}$ ($-10^{\circ}{\sim}5^{\circ}$) and 0.22 (-0.15~0.6) preoperatively to $2.8^{\circ}$ ($1^{\circ}{\sim}5^{\circ}$) and 0.42 (0.3~0.6) postoperatively, respectively. Conclusion: If there is persistent sinus tarsi pain in patients with hindfoot valgus, accessory talar facet impingement caused by AALTF could be considered as a cause of chronic sinus tarsi pain.

• Journal of Sasang Constitutional Medicine
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• v.11 no.1
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• pp.137-157
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• 1999

The purpose of this study is to help classifying Sasang Constitution through correlation with sound characteristic. This study was done it under the suppose that Sasang Constitution has correlation with sound spectrogram. The following result were obtained about correlation between sound spectrogram and Sasang Constitution by comparison and analysis 1. Soeumin answered his voice low tone, smooth and quiet in the survey. Soyangin answered his voice high, clear, fast and speaking random. Taeumin answered his voice low, thick and muddy. 2. Taeyangin was significantly slow compared with the others in the time of reading composition. Taeyangin was significantly slow compared with the others in Formant frequency 1. Taeyangin was significantly discriminated from Soeumin in Formant frequency 5. Taeyangin was significantly low compared with the others in Bandwidth 2. Soeumln was significantly low compared with Taeyangin in Pitch Maximum and Pitch Maximum-Pitch Minimum. Taeyangin was significantly high compared with the others in Energy mean. 3. In list of specification, the discrimination rate was higher than that by lists of 13 in the results of Multi-dimensional 4-class minimum-distance. The discrimination rate of three disposition except Soyangin was higher than that of four disposition in the results of One way ANOVA and Analysis of dis crimination in SPSS/PC+. In CART, the estimate rate of Sasang Constitution discrimination was higher than any other method. It is considered that there is a correlation between sound spectrogram and Sasang constitution according to the results. And method of Sasang constitution classification through sound spectrogram analysis can be one method as assistant for the objectification of Sasang constitution classification.

• Proceedings of the KSPS conference
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• 1996.10a
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• pp.574-575
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• 1996

The theme of the current study is to study intonation of Taiwanese(Tw.) by comparing the intonation patterns in native language (Ll), target language (L2), and interlanguage (IL). Studies on interlanguage have dealt primarily with segments. Though there were studies which addressed to the issues of interlanguage intonation, more often than not, they didn't offer evidence for the statement, and the hypotheses were mainly based on impression. Therefore, a formal description of interlanguage intonation is necessary for further development in this field. The basic assumption of this study is that native speakers of one language perceive and produce a second language in ways closely related to the patterns of their first language. Several studies on interlanguage prosody have suggested that prosodic structure and rules are more subject to transfer than certain other phonological phenomena, given their abstract structural nature and generality(Vogel 1991). Broselow(1988) also shows that interlanguage may provide evidence for particular analyses of the native language grammar, which may not be available from the study of the native language alone. Several research questions will be addressed in the current study: A. How does duration vary among native and nominative utterances\ulcorner The results shows that there is a significant difference in duration between the beginning English learners, and the native speakers of American English for all the eleven English sentences. The mean duration shows that the beginning English learners take almost twice as much time (1.70sec.), as Americans (O.97sec.) to produce English sentences. The results also show that American speakers take significant longer time to speak all ten Taiwanese utterances. The mean duration shows that Americans take almost twice as much time (2.24sec.) as adult Taiwanese (1.14sec.) to produce Taiwanese sentences. B. Does proficiency level influence the performance of interlanguage intonation\ulcorner Can native intonation patterns be achieved by a non-native speaker\ulcorner Wenk(1986) considers proficiency level might be a variable which related to the extent of Ll influence. His study showed that beginners do transfer rhythmic features of the Ll and advanced learners can and do succeed in overcoming mother-tongue influence. The current study shows that proficiency level does play a role in the acquisition of English intonation by Taiwanese speakers. The duration and pitch range of the advanced learners are much closer to those of the native American English speakers than the beginners, but even advanced learners still cannot achieve native-like intonation patterns. C. Do Taiwanese have a narrower pitch range in comparison with American English speakers\ulcorner Ross et. al.(1986) suggests that the presence of tone in a language significantly inhibits the unrestricted manipulation of three acoustical measures of prosody which are involved in producing local pitch changes in the fundamental frequency contour during affective signaling. Will the presence of tone in a language inhibit the ability of speakers to modulate intonation\ulcorner The results do show that Taiwanese have a narrower pitch range in comparison with American English speakers. Both advanced (84Hz) and beginning learners (58Hz) of English show a significant narrower FO range than that of Americans' (112Hz), and the difference is greater between the beginning learners' group and native American English speakers.

• Journal of Korean Foot and Ankle Society
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• v.14 no.2
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• pp.177-181
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• 2010

Purpose: The author evaluated the clinical and radiological results after wearing the medial arch supports in children. Materials and Methods: 103 patients who had symptomatic flat feet were evaluated from march, 2002 to may 2009. All patients wore the medial arch supports according to the symptoms. We measured parameters at weight-bearing radiographs before and after medial arch support were worn. We also evaluated the clinical scores using the AOFAS score. Results: Mean age of patients was 97 months (11-204 months), all foot of patients involved bilaterally. Mean talo-first metatarsal angle of right foot was $17.7{\pm}9.4$ and left foot was $19.96{\pm}9.5$ degrees at AP radiograph in pre-wearing state. Mean calcaneal pitch angle of right foot was $12.0{\pm}5.3$ and left foot was $11.9{\pm}5.8$ degrees at lateral radiograph in pre-wearing state. Mean talo-first metatarsal angle of right foot was $14.4{\pm}8.05$ and left foot was $13.1{\pm}8.77$ degrees at AP radiograph in post-wearing state. Mean calcaneal pitch angle of right foot was $16.4{\pm}5.75$ left foot was $16.5{\pm}5.6$ degrees at lateral radiograph in post-wearing state. The radiographic angles between pre-wearing and post-wearing state were statistically significant (p<0.05). Mean pre-wearing AOFAS hindfoot score was $66.7{\pm}9.25$, midfoot score was $60.0{\pm}9.34$ forefoot score was $57.1{\pm}11.8$. Mean post-wearing AOFAS hindfoot score was $73.2{\pm}9.73$, midfoot score was $68.1{\pm}10.1$, forefoot score was $67.2{\pm}11.4$. The forefoot score was highest improving scores among the AOFAS scores. Conclusion: From our study, we concluded that medial arch support was effective for symptomatic flat feet of children in radiological and clinical results from our study.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.307-312
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• 2017

In this study, the electrochemical performance of surface modified carbon using the PFO (pyrolyzed fuel oil) was investigated by chemical activation with KOH and $K_2CO_3$. PFO was heat treated at $390{\sim}400^{\circ}C$ for 1~3h to prepared the pitch. Three carbon precursors (pitch) prepared by the thermal reaction were 3903 (at $390^{\circ}C$ for 3h), 4001(at $400^{\circ}C$ for 1h) and 4002 (at $400^{\circ}C$ for 2h). Also, the effect of chemical activation catalysts and mixing time on the development of porosity during carbonization was investigated. The prepared carbon was analyzed by BET and FE-SEM. It was shown that chemical activation with KOH could be successfully used to develop carbon with specific surface area ($3.12m^2/g$) and mean pore size (22 nm). The electrochemical characteristics of modified carbon as the anode were investigated by constant current charge/discharge, cyclic voltammetry and electrochemical impedance tests. The coin cell using pitch (4002) modified by KOH has better initial capacity (318 mAh/g) than that of other pitch coin cells. Also, this prepared carbon anode appeared a high initial efficiency of 80% and the retention rate capability of 2C/0.1 C was 92%. It is found that modified carbon anode showed improved cycling and rate capacity performance.