• Journal of Animal Environmental Science
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• v.6 no.2
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• pp.121-130
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• 2000

Pure voice characteristics of sow were analyzed to predict parturition time. These were analyzed by using oscilloscope and Sound Forge and the results showed that the voice frequency and amplitude of sow were in the range of 30∼2,500Hz and -35∼-75dB. According to the sound analysis results, the frequencies of sound appearance from farrowing sow in the farrowing pen for three days prior to delivery day and eight hours of prior to delivery day and eight hours of prior to time were around 85% and 46%, respectively of the total appearance during eight days to delivery. Forecasting of delivery time of farrowing sow using the number of sound occurrences showed a promising result such that those have been increased whenever the delivery time was approached. The forecasting success rates were 100% for both of one day and six hours prior to the actual delivery.

• Reproductive and Developmental Biology
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• v.31 no.3
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• pp.215-220
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• 2007

This study was conducted to examine the establishment of bovine ES-like cells having pluripotency. The hatched blastocysts derived from culture of in vitro fertilized embryos for 10 to 12 days dissociated mechanically into ICM-and trophectoderm-rich clumps using needle, and cultured onto mitotically-inactivated MEF feeder layer. The primary colonies originated from ICM cells were detached mechanically 7 days after seeding and subsequent subculture was conducted at intervals of every 5 to 7 days. Two ES -like cell lines were established and maintained over 40 passages. Self-renewal of the established lines was confirmed by examining the alkaline phosphatase activity, stem cell-specific marker profiles including SSEA isotopes, Oct-4 and STAT3. Moreover, the established cell lines could produce anchorage-independent embryoid bodies (EBs) with gradual decrease of Oct-4 transcript level in time-dependent manner.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.11a
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• pp.63-63
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• 2002

현재 기계적 합금화법에서는 주로 합금을 구성하는 성분원소 분말을 불활성분위기에서 볼밀처리 함으로써 함금화를 시키거나 모합금에 산화물을 분산시켜 복합화시키는 공정을 통하여 각종 화합물, 비정질상 및 과포화고용체등의 준안정상의 합성 뿐만이 아니라 초미세조직의 생성에 관한 폭 넓은 분야의 연구가 행하여지고 있다. 한편 MA에서는 볼멀처리중 기계적 에너지의 투여에 의하여 실제 반응온도보다 낮은 온도에서 발생하는 특이한 화학반응 즉 Mechanochemical 반응을 일으키 기도 한다. 본 연구에서는 헤마타이트($Fe_20_3$)와 금속윈소인 Ti의 MA처리에 의하여 고상환원반응 을 유기시켜 $Fe-TiO_2$계 nanocomposite 분말재료를 제조하고자 한다. 특히 MA 공정에 있어서 자기 물성의 변화와 X선 회절을 통하여 고상환원반응에 의한 복합분말의 생성과정을 조사하였다. 출발원료는 $Fe_20_3$(고순도화학제,99.9%, 평균입경 0.1$\mu\textrm{m}$)와 금속원소인 Ti(99.9%, 명균업경 150$\mu\textrm{m}$)을 몰비 2:3의 조성이 되도록 하여 MA를 실시하였다. 볼멀은 고에너지 유성형 볼밀장치(독일 제, Fritsch P-5)를 이용하였으며 진공치환형 용기에 원료분말을 장입하여 2회정도 진공배기한 후 아르곤 가스를 충전하여 볼밀을 행하였다. 얻어진 분말시료에 대하여 x-선 회절장치, 전자현미경 (SEM) 및 진동시료형자력계(VSM)를 통하여 결정구조, 미셰조직 빛 자기특성을 조사하였다. $Fe_2O_3-Ti$ 혼합분말의 MA처리 에 의하여 초기단계부터 환원반응과 함께 $Fe_3TIO_{lO}$ 중간상이 관찰 되었으나 30hrs의 MA처리 후 Fe와 산화물 $TiO_2$로 모두 환원되어 $Fe-TiO_2$계 나노복합분말이 얻어짐을 알 수 있었다. 이 때 X션 회절피크의 line broadening으로부터 복합분말의 Fe 명균 결정립 크기는 24nm로 초미세 결정럽의 분말합금이었다. 포화자화값은 볼밀처리에 따라 점점 증가하여 MA 30시간에는 20.3emu/g로 포화됨을 알 수 있었다. 또한 보자력 Hc는 MA초기단계에 350e로 매우 낮으나 30시간 후에는 Hc값이 2600e로 매우 큰 값을 나타내었다. 이것은 환원반응결과 초기에 생성된 Fe의 결정립이 비교적 크고 결정결함이 적으나 볼밀처리를 30시간까지 행하면 Fe 결정렵의 미세화 빛 strain 증가로 magnetic hardening이 일어나기 때문인 것으로 사료된다.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.14 no.1
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• pp.16-25
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• 2003

Background and Objectives : Electroglottography(EGG) is a non-invasive method of monitoring the vocal cord vibration by measuring the variation of physiological impedance across the vocal folds through the neck skin. It reveals especially the vocal fold contact area and is widely used for basic laryngeal researches, voice analysis and synthesis. The purpose of this study is to investigate the effectiveness of EGG parameters in differential diagnosis of laryngeal cancer. Materials and Methods : The author investigated 10 laryngeal cancer and 25 benign laryngeal disease patients who visited at the Department of Otolaryngology, Pusan National University Hospital. The EGG equipment was devised in the author's Department. Among various parameters of EGG, closed quotient(CQ), speed quotient(SQ), speed index(SI), Jitter, Shimmer, Fo were determined by an analysis program made with MATLAB 6.5$^{\circledR}$(Mathwork, Inc.). In order to differentiate various laryngeal diseases from pathologic voice signals, the author has used the electroglottographic parameters using the neural network of multilayer perceptron structure. Results : SQ, SI, Jitter and Shimmer values except those of CQ and Fo showed remarkable differences between benign and malignant laryngeal disease groups. From the artificial neural network, the percentage of differentiating the laryngeal cancer was over 80% in SQ, SI, Jitter, Shimmer except for CQ and Fo. These results indicated that it is possible to discriminate the benign and malignant laryngeal diseases by EGG parameters using the artificial neural network. Conclusion : If parameters of EGG which can reveal for the pathology of laryngeal diseases are additionally developed and the current classification algorithm is improved, the discrimination of laryngeal cancer will become much more accurate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.140-145
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• 2018

This paper deals with the dynamical analysis of a two-point mooring vessel under surge excitations. The characteristics of nonlinear behaviors are investigated completely including bifurcation and limit cycle according to particular input parameter changes. The strong nonlinearity of the mooring system is mainly caused by linear and cubic terms of restoring force. The numerical simulation is performed based on the fourth order Runge-Kutta algorithm. The bifurcation diagram and several instability phenomena are observed clearly by varying amplitudes as well as frequencies of surge excitations. Stable periodic solutions, called the periodic windows, can be obtained in succession between chaotic clouds of dots in case of frequency ${\omega}=0.4rad/s$. In addition, the chaotic region is unexpectedly increased when external forcing amplitude exceeds 1.0 with the angular frequency of ${\omega}=0.7rad/s$. Compared to the cases for ${\omega}=0.4$, 0.7rad/s, the region of chaotic behavior becomes more fragile than in the case of ${\omega}=1.0rad/s$. Finally, various types of steady states including sub-harmonic motion, limit cycle, and symmetry breaking phenomenon are observed in the two-point mooring system at each parameter value.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.107-116
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• 2000

Pure voice characteristics of sow were analyzed to predict parturition time. These were analyzed by using oscilloscope and Sound Forge and the results showed that the voice frequency and amplitude of sow were in the range of 30~2,500Hz and -35~-75dB. According to the sound analysis results, the frequencies of sound appearance from farrowing sow in the farrowing pen for three days prior to delivery day and eight hours of prior to time were around 85% and 46%, respectively of the total appearance during eight days to delivery. Forecasting of delivery time of farrowing sow using the number of sound occurrences showed a promising result such that those have been increased whenever the delivery time was approached. The forecasting success rates were 100% for both of one day and six hours prior to the actual delivery.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.251-258
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• 2018

In construction site, conventional methods such as jackhammer or explosive methods(dynamite) have been often used for the demolition of structures. Use of those methods are more carefully treated in environmentally and historically sensitive area. For those reasons, use of Soundless Chemical Demolition Agent(SCDA) is getting the spotlight. The SCDA is a powder which has expansive strength when it is mixed with water. In these Characteristics, SCDA can destroy the concrete or rock as it is poured into boreholes of the concrete or rock structures. However, there is no industrial standard for the use of SCDA effectively yet. In this study, experimental study to measure the expansive pressure was conducted depending on various boundary conditions such as waterproof, length of the steel pipe, submerged of steel pipe. Furthermore, computational analysis using damage plasticity model to predict the minimum required pressure of the SCDA for the concrete demolition depending on spacing between holes(k-factor) and compressive strength of the concrete was conducted. Obtained results indicates that water heat dissipation with submerged steel pipe shows the stable pressure for measuring the SCDA and hole distance(k-factor) is the most important factor for crack initiation of concrete.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.293-301
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• 2017

A Sub-kWe small-scale experimental test loop was manufactured to investigate characteristics of the supercritical carbon dioxide power cycle. A high-speed turbo-generator was also designed and manufactured. The designed rotational speed of this turbo-generator was 200,000 rpm. Because of the low expansion ratio through the turbine and low mass flowrate, the rotational speed of the turbo-generator was high. Therefore, it was difficult to select the rotating parts and design the turbine wheel, axial force balance and rotor dynamics in the lab-scale experimental test loop. Using only one channel of the nozzle, the partial admission method was adapted to reduce the rotational speed of the rotor. This was the world's first approach to the supercritical carbon dioxide turbo-generator. A cold-run test using nitrogen gas under an atmospheric condition was conducted to observe the effect of the partial admission nozzle on the rotor dynamics. The vibration level of the rotor was obtained using a gap sensor, and the results showed that the effect of the partial admission nozzle on the rotor dynamics was allowable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.737-742
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• 2017

Recently, unconventional high-rise building shapes have attracted attention as a landmark of metropolitan cities and the search for innovative building forms in architecture is ongoing. In this study, $Isotruss^{(R)}$ grid(ITG) used in smaller scale structures was applied to building structural systems and its structural performance was examined. The structural behavior of an ITG was compared with that of a diagrid structure as a reference structure. The stiffness-based design method of the diagrid system was used for the preliminary design stage of member sizing in an ITG. The structural design of 16, 32, and 48-story buildings was carried out for the two systems with the same size. The angle of the inclined columns for ITG and diagrid was $59^{\circ}$ and $68.2^{\circ}$, respectively. The lateral stiffness, steel tonnage of the exterior frame, axial strength ratio, story drift ratio, and natural frequency of the two systems were compared. Based on the analysis result of 6 buildings, the two systems had similar structural capacity; 93.3% and 88.7% of the lateral load was carried by the perimeter frame in the ITG system and diagrid system, respectively. This suggests that the ITG system is better in arranging core columns. Therefore, the proposed ITG system has not only a unique façade, but also substantial structural capacity equivalent to the existing system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.21-30
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• 2008

The fuel cell generation convert fuel source, and gas directly to electricity in an electro-chemical process. Unlike traditional and conventional turbine engines, the process of fuel cell generation do not burn the fuel and run pistons or shafts, and it has not revolutionary machine, so have fewer efficiency losses, low emissions and no noisy moving parts. A high power density allows fuel cells to be relatively compact source of electric power, beneficial in application with space constraints. In this system, the fuel cell itself is nearly small-sized by other components of the system such as the fuel reformer and power inverter. So, the fuel cell energy's stationary fuel cells produce reliable electrical power for commercial and industrial companies as well as utilities. In this paper, a fuel cell system has been modeled using PSCAD/EMTDC to analyze its electric signals and characteristics. Also the power quality of the fuel cell system has been evaluated and the problems which can be occurred during its operation have been studied by modeling it more detailed. Particularly, we have placed great importance on its power quality and signal characteristics when it is connected with a power grid.