• 음성과학
• /
• 제5권1호
• /
• pp.49-62
• /
• 1999

This study is concerned with the educational program Visual Analysis Tool (VAT) for sound development for foreign intonation using personal computer. The VAT can run on IBM-PC 386 compatible or higher. It shows the spectrogram, waveform, intensity and the pitch contour. The system can work freely on either waveform zoom in-out or the documentation of measured value. In this paper, intensity and pitch contour information were used. Twelve French sentences were recorded from a French conversational tape. And three Korean participated in this study. They spoke out twelve sentences repeatly and trid to make the same pitch contour - by visually matching their pitcgh contour to the native speaker's. A sentences were recorded again when the participants themselves became familiar with intonation, intensity and pauses. The difference of pitch contour(rising or falling), pitch value, energy, total duration of sentences and the boundary of rhythmic group between native speaker's and theirs before and after training were compared. The results were as following: 1) In a declarative sentence: a native speaker's general pitch contour falls at the end of sentences. But the participant's pitch contours were flat before training. 2) In an interrogative: the native speaker made his pitch contours it rise at the end of sentences with the exception of wh-questions (qu'est-ce que) and a pitch value varied a greath. In the interrogative 'S + V' form sentences, we found the pitch contour rose higher in comparison to other sentences and it varied a great deal. 3) In an exclamatory sentence: the pitch contour looked like a shape of a mountain. But the participants could not make it fall before or after training.

• 전기학회논문지P
• /
• 제63권4호
• /
• pp.254-259
• /
• 2014

In this paper, we describe construction of a wind stabilization demo-site and effects of output power control of wind turbines for suppression of ramp rate using ESS (Energy Storage System). It is difficult to control the output power of distributed generator such as wind turbine which of variation is very large. If the large capacity wind farm be interconnected into power system may cause blackout due to Power Quality. For these reasons, the international standards such as Grid-Code is limited to less than 10 [%/min] of renewable energy ramp rate. The case of Korea, government actively conducts propagating large-scale renewable energy for green growth policy, to interconnecting more renewable energy into power system is necessary for stabilization technology. For these reasons, the POSCO consortium has constructed a wind stabilization demo-site that is configured as 500 [kWh] battery energy storage systems can output up to 3 [C-Rate] and two wind turbines rated 750 [kW]. In POSCO consortium, which implements various methods stabilizing output power of wind turbine such as smoothing, section firming and ramp control, we derive the results of long-term demonstration that can be controlled to satisfy to the international standard about ramp rate [%/kW] of wind turbine output power.

• 자원리싸이클링
• /
• 제6권1호
• /
• pp.29-34
• /
• 1997

산업 폐기물의 일종인 석회석 슬러지, 폐주물사, 석탄회 및 폐유리병을 고온에서 용융 슬래그화 하여 시멘트 원료로서의 활용 가능성을 검토하고자 하였다. 각 폐기물을 혼합한 후 용융처리하여 얻은 용융 슬래그는 $\beta$-$C_2$S(2CaO.$SiO_2$) 및 $C_2$AS(2CaO.$Al_2$$O_3$.$SiO_2$)의 2가지 상으로 구성되어 있다. 폐기물의 용융처리시 용융온도, 냉각속도 및 염기도 등을 변화시키면서 이들 요인이 $\beta$-$C_2$S상의 생성율에 미치는 영향을 조사하였다. 시멘트 원료로서 활용이 가능한 $\beta$-$C_2$S상의 함율을 높이기 위해서는 첫째 용융온도를 낮추어 용융슬래그의 제조에 필요한 최소한의 온도에서 용융시키고, 둘째 용융물을 고온에서 급냉시키며, 셋째 낮은 염기도를 갖도록 혼합물의 조성을 조절하는 것이 필요하다.

• 농업과학연구
• /
• 제44권3호
• /
• pp.416-423
• /
• 2017

This study aimed to identify milling characteristics depending on the rotating speed of the main shaft of the cutting-type rice milling machine which can minimize the conventional milling process. Brown rice, which was produced in Gunsan-si, Jeollabuk-do, Republic of Korea, in 2016, was used as the experimental material. The milling characteristics of white rice were measured under four different rotating speeds of main shaft: 950 - 1,050 rpm, 1,000 - 1,100 rpm, 1,050 - 1,150 rpm, and 1,100 - 1,160 rpm. For each shaft speed, 300 kg of brown rice was processed, and the milling characteristics were measured according to the whiteness, grain temperature, cracked rice ratio, broken rice ratio, turbidity, and energy consumption. The whiteness of rice grain was found to be consistent at around $40{\pm}0.5$ only when milled at the shaft speed of 950 - 1,050 or 1,000 - 1,100 rpm. The grain temperature during the milling process increased by 11.35 to $11.85^{\circ}C$, showing little differences amongst shaft speeds. The cracked rice ratio increased by 8.2 to 10.4% at all conditions. The broken rice ratio ranged from 0.58 to 0.76%, reflecting a low level. The turbidity after milling was 54.8 ppm when milled at 1,000 - 1,100 rpm. Energy consumption of 12.98 and 12.18 kWh/ton were recorded at the shaft speed of 1,000 - 1,100 and 1,050 - 1,150 rpm, respectively. The result of this study indicates that the optimal rotating speed of main shaft would be 1,000 - 1,100 rpm for a cutting-type rice milling machine.

• Advances in Energy Research
• /
• 제5권3호
• /
• pp.227-237
• /
• 2017

The continuous increase of emission rates of green house gases and the effects on global warming added a new dimension to the problem of substituting the petroleum and its derivatives by environment friendly and sustainable energy sources for the world. Solar and wind energy appear at the top of the list of renewable of high potential, widely available, of dominated technology and well accepted. Brazil is one of the few countries in the world that receives number hours of sunshine exceeding 3,000 hours per year with a daily average of 4.5 to 6 kWh. However, this potential is largely unexplored and poorly tapped. The number of renewable systems implanted in Brazil has grown in recent years, but still insignificant when compared, for example, with Germany and Spain among others. This paper presents the results of an optical study on small concentration solar collector with evacuated tube enveloping the absorber and internal reflective surface fixed on the bottom part of the evacuated tube. The designed collector has a 2D geometrical concentration ratio between 2.455 and 4.91. The orientation of the solar collector, the ratio of the radius of the receiver to the radius of the absorber, the incidence angle for each period of the year, the collector inclination angle, the aperture angle of the reflective surface, concentration and optical efficiency were determined. The ray traces and flux distribution on the absorber of the evacuated tube solar collector were determined by using the program Ray Optics Simulation. The optical efficiency varies during the year according to the solar declination. For the periods were the solar declination is close to zero the efficiencies are maximum, and the variation during the day is around 25.88% and 99.9%. For the periods were the solar declination is maximum the efficiencies are minimum, and the variation during the day is around 23.78% and 91.79%.

• 한국태양에너지학회 논문집
• /
• 제31권6호
• /
• pp.103-110
• /
• 2011

The aim of this study was to analysis the Heating/cooling performance and Daylighting performance of Solar Window System built in apartments. the solar window is the idea to integrate daylight as a third form of solar energy into a PV/Solar Collector system. The process of this study is as follows: 1)Solar Window system was designed through the investigation of previous paper and work. 2)The simulation program(Lightscape3.2) was used in daylighting performance analysis. the reference model of simulation was made up to analysis daylighting performance on Solar Window system. 3)The simulation program(ESP-r, Therm5.0, Window6.0) was used in energy performance analysis. the reference model of simulation was made up to analysis energy and daylighting performance on Solar Window system. 4)The Size of Simulation model for daylighting and heating/cooling energy analysis was $148.5m^2$ 5)The lighting performance analysis was carried out with various variants, such as the size and installed area of Solar Window system. 6)Energy performance simulation was carried out with various variants, such as Integrated U-value of Solar Window system according to its position, installed angle and insulation thickness. Consequently, When Solar Window system is equipped with balcony window of Apartment, Annual heating and cooling energy of reference model was cut down at the average of $4.1kWh/m^2$ or 4.2%.

• 대한전자공학회논문지SP
• /
• 제42권6호
• /
• pp.195-202
• /
• 2005

적응 분할 알고리즘은 국부 비 균질 영상에서 효율적인 표적 탐지를 위해 사용된다. 지금까지 영상 분할에 여러 가지 적응방법이 제안되었다. 하지만 이들 알고리즘이 레이다 표적 탐지에 바로 적용하기는 어려운데 이는, 레이다 자체 신호 특성 때문이다. 일반적으로 레이다 표적은 배경신호에 비해 상대적으로 적은 도수 함수를 갖고 있으며, 배경 분포는 외부환경에 따라 다양한 형태를 갖는다. 본 논문에서는 도수함수의 최대 값에서 우측 하향 직선인 히스토그램 현을 이용한 적응 표적분할 알고리즘을 제안한다. 제안한 방식은 임계값 탐색에 사용되는 적용 현이 외부환경조건에 영향을 적게 받음으로 인해 다양한 레이다 환경에 최적인 임계 값을 선택한다. 시뮬레이션 결과, 제안한 알고리즘이 기존 표적분할알고리즘인 전역 임계 값 방법 및 분포 중앙값 추정방식에 비해 탐지성능측면에서 우수함을 보였다.

• 음성과학
• /
• 제7권4호
• /
• pp.203-217
• /
• 2000

In spoken language, the characteristics of prosodic realization are related to the meaning of utterance. The pitch pattern of an interrogative sentence which differs from that of declarative sentences can be considered in this respect.. If we consider the question-answer pair, we can find that the most important variation comes from the intended meaning of asking. In this paper, we experiment with four kinds of interrogative sentences and show that the difference in pitch patterns of interrogative sentences can be explained in relation to the focus phenomena that is, the differences of the boundary tones in interrogative sentences are due to the differences in the prosodic domain of focus. For a relevant explanation with the focus phenomena, we divided focus into the categories: emphatic focus, which plays a role in delivering the speaker's intended meaning for the sentence interpretation, and informational focus, delivers the central intended meaning of the utterance. The results can be summarized in three points. First, High boundary tone delivers the meaning of asking. Second, the realization of different boundary tones that are found in wh-question and alternative question are just phonetic variations caused by focusing. Third, the high rise boundary tone in echo questions is related to the meaning of surprise or incredulity, and this relation is a consensus of existing opinion, that is, the speaker's attitude of surprise can raise the pitch range. From these results we can distinguish between boundary type and phonetic variation, and we can also give appropriate meaning to the different boundary tones in interrogative sentences that have been regarded as merely a part of sentence type.

• 한국수소및신에너지학회논문집
• /
• 제30권6호
• /
• pp.490-498
• /
• 2019

The intermittent electric power supply of renewable energy can have extremely negative effect on power grid, so long-term and large-scale storage for energy released from renewable energy source is required for ensuring a stable supply of electric power. Power to gas which can convert and store the surplus electric power as hydrogen through water electrolysis is being actively studied in response to increasing supply of renewable energy. In this paper, we proposed the novel concept of hydrogen liquefaction process combined with pre-cooling process using the liquid air. It is that hydrogen converted from surplus electric power of renewable energy was liquefied through the hydrogen liquefaction process and vaporization heat of liquid hydrogen was conversely recovered to liquid air from ambient air. Moreover, Comparisons of specific energy consumption (kWh/kg) saved for using the liquid air pre-cooling was quantitatively conducted through the performance analysis. Consequently, about 12% of specific energy consumption of hydrogen liquefaction process was reduced with introducing liquid air for pre-cooling and optimal design point of helium Brayton cycle was identified by sensitivity analysis on change of compression/expansion ratio.

• 한국대기환경학회지
• /
• 제27권4호
• /
• pp.387-394
• /
• 2011

A study on the removal of sulfur dioxide and nitrogen oxide was carried out using a non-thermal nano-pulse corona discharger at different gas temperatures. Pulse voltage with a high voltage of 50 kV, a pulse rising time of about 100 ns, a full width at half maximum of about 500 ns and a frequency of 1 kHz was applied to a wire-cylinder corona reactor. Ammonia and propylene gases were added into the corona reactor as additives with a static mixer. Ammonia addition had less effect on $SO_2$ reduction at the higher temperature because of the retardation of ammonium sulfate formation. However, propylene addition enhanced NO reduction at higher temperature due to increased gas mixture. $SO_2$ was further removed at the mixed $SO_2$ and NO gas due to increased $NO_2$ by the conversion of NO. The addition of ammonia and propylene gases was more highly dominant for the removal of sulfur dioxide compared to the sole pulse corona without the additives. However, the specific energy density per unit concentration of pulse corona as well as propylene additive was an important factor to remove NO gas. Therefore, the specific energy density per unit concentration of 0.04 Wh/($m^3{\cdot}ppm$) was necessary for the NO removal of more than 80% with the concentration ratio of 2.0 for propylene and NO. Hydrogen peroxide was another alternative additive to remove both $SO_2$ and NO in the nano-pulse corona discharger.