• 한국안전학회지
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• 제8권4호
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• pp.189-193
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• 1993

Elimination of dangerous points is the most effective method for safety in mechanical equipments. The next effective method is recognized as isolation and/or safe-guarding of dangerous spots from human beings. With progress of mechanical automation technique such as industrial robots, the need for safe-guard-ins is now being enlarged. It is needless to say that when a machine-guard is designed and installed, a comprechensive understanding of human movement is indispensable. But in this country, there is no scientific for those thems, and no one verifield whether it is valid to apply general guideline such as OSHA's to Korean or not. Further, basic anthropometric items for safety reach standards are neither availble nor included in nation-wide anthropometry project. In this research, human anthropometry data of Korean youngsters are analyzed for safety barrier and safety slit width, and compared with guidelines of other countries-Germany, United Kingdom, Japan, and USA. Though they are standards for safety, since they are based upon their own peoples' data, some of them especially foot reach are not not applicable in this country. It should be notified that careful application of numeric value is very important.

• Journal of Magnetics
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• 제18권1호
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• pp.50-56
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• 2013

In this paper, the 6-switch inverter for the Flux-Reversal Motor (FRM) has been presented and compared to the 4-switch inverter for the FRM, which is more popular in cost effective applications. To analyze the FRM, we adopted the two-dimensional time-stepped voltage source finite element method (FEM) that uses the actual pulse width modulation (PWM) voltage waveforms as the input data. As the FRM characteristic analysis of actual pwm voltage input, the torque ripples and iron losses (eddy current and hysteresis loss) of the FRM can be precisely calculated. With the simulated and experimental results, the performance and limitations of the 4-switch FRM which is the cost effective drive compared to the 6-switch FRM drive are provided in more detail.

• ETRI Journal
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• 제45권6호
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• pp.974-981
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• 2023

This paper presents a transition-limited pulse-amplitude modulation (TLPAM) signaling method to enable a high data rate and robust wireline communications. TLPAM signaling addresses the impact of high intersymbol interference (ISI) ratios in conventional M-ary PAM signaling methods by limiting the maximum voltage transition level between adjacent symbols. The implementation of a TLPAM signaling encoder is realized by setting back the most significant bits (MSBs) in the queue. The correlation between TLPAM's maximum transition level, effective data rate, and eye width/height is analyzed with various channel loss parameters, followed by characterization and measurement results with a realistic channel setup. The analysis and experimental results reveal the effectiveness of the proposed TLPAM signaling scheme for achieving a high data rate with minimal interference.

• 한국통신학회논문지
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• 제12권1호
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• pp.36-49
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• 1987

하이브리드 모드 마이크로 스트립 線路에서 周波數의 函數인 實效誘電率 및 實效幅에 따른 正規化 位相速度와 特性 임피던스의 分散特性을 計算하기 爲한 Planar Waveguide 모델이 提示되었으며. Eeff(f)와 Weff(f)는 周波數에 따른 實驗關係式과 CAD를 目的으로 設定된 計算式을 利用하여 Planar Waveguide모델 計算에 適用하였고, 多樣한 比誘電率과 스트립 幅/基板 두께(W/h)는 $0.5$\leq$W/h\leq2.5의$ 比를 使用하여, 그 結果를 稱的値, Spectral domain 解析 및 實驗關係 結果 等과 比較하였다. 컴퓨터 시뮬레이션 結果, Planar Waveguide 모델을 利用할 境遇가 이미 發表된 바 있는 다른 方法보다 周波數가 增加함에 따라 周波數 別 正規化 位相速度는 1/ 의 값에 가장 接近하였고 特性 임피던스는 더욱 增加하였다. 또한, CAD를 目的으로 設定된 Eeff(f)를 本 提案 모델이 適用한 境遇가 實驗關係式을 利用한 境遇보다 더 좋은 結果를 얻을 수 있었다.

• Computers and Concrete
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• 제19권6호
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• pp.711-716
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• 2017

This paper presents a method using artificial neural networks (ANNs) to predict the residual moment capacity of thermally insulated reinforced concrete (RC) beams exposed to fire. The use of heat resistant insulation material protects concrete beams against the harmful effects of fire. If it is desired to calculate the residual moment capacity of the beams in this state, the determination of the moment capacity of thermally insulated beams exposed to fire involves several consecutive calculations, which is significantly easier when ANNs are used. Beam width, beam effective depth, fire duration, concrete compressive and steel tensile strength, steel area, thermal conductivity of insulation material can influence behavior of RC beams exposed to high temperatures. In this study, a finite difference method was used to calculate the temperature distribution in a cross section of the beam, and temperature distribution, reduction mechanical properties of concrete and reinforcing steel and moment capacity were calculated using existing relations in literature. Data was generated for 336 beams with different beam width ($b_w$), beam account height (h), fire duration (t), mechanical properties of concrete ($f_{cd}$) and reinforcing steel ($f_{yd}$), steel area ($A_s$), insulation material thermal conductivity (kinsulation). Five input parameters ($b_w$, h, $f_{cd}$, $f_{yd}$, $A_s$ and $k_{insulation}$) were used in the ANN to estimate the moment capacity ($M_r$). The trained model allowed the investigation of the effects on the moment capacity of the insulation material and the results indicated that the use of insulation materials with the smallest value of the thermal conductivities used in calculations is effective in protecting the RC beam against fire.

• 한국강구조학회 논문집
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• 제16권4호통권71호
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• pp.463-470
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• 2004

본 연구에서는 중심축하중을 받는 각형강관기둥의 베이스플레이트의 지압응력의 분포와 설계에 대하여 조사하였다. 일반적으로 강구조 기둥의 베이스플레이트는 지압응력이 등분포하다고 가정하고 그 크기와 두께를 결정한다. 그러나 축하중이 적으면 베이스플레이트의 크기도 작아지고 두께도 얇아지며 지압응력은 등분포하게 되지 않으며 기둥단면의 하부에 집중된다. 본 연구에서는 실험적 방법과 해석적 방법으로 지압응력의 분포에 대하여 조사하고 그 결과를 이용하여 설계법을 검토하였다. 4개의 각형강관기둥 베이스플레이트 시험체를 제작하여 실험을 수행하였다. 또한 유한요소해석프로그램인 ANSYS를 이용하여 베이스플레이트의 지압응력의 분포를 해석하였다. 연구결과 축하중이 적은 경우 지압응력은 기둥단면의 하부에 집중되고 등분포하지 않으므로 유효폭의 개념을 이용하여 베이스플레이트를 설계하는 방법이 적절함을 나타내었다.

• 천문학회지
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• 제42권3호
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• pp.55-60
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• 2009

The properties of SOHO/LASCO CMEs are subjected to projection effects. Their dependence on the source position is important to be studied. Our main aim is to study the dependence of CME properties on helio-longitude and latitude using the CMEs associated with type IIs observed by Wind/WAVES spacecraft (Deca-hecta metric type IIs - DH type IIs). These CMEs were identified as a separate population of geo-effective CMEs. We considered the CMEs associated with the Wind/WAVE type IIs observed during the period January 1997 - December 2005. The source locations of these CMEs were identified using their associated GOES X-ray flares and listed online. Using their locations and the cataloged properties of CMEs, we carried out a study on the dependence of CME properties on source location. We studied the above for three groups of CMEs: (i) all CMEs, (ii) halo and non-halo CMEs, and (iii) limb and non-limb CMEs. Major results from this study can be summarized as follows. (i) There is a clear dependence of speed on both the longitude and latitude; while there is an increasing trend with respect to longitude, it is opposite in the case of latitude. Our investigations show that the longitudinal dependence is caused by the projection effect and the latitudinal effect by the solar cycle effect. (ii) In the case of width, the disc centered events are observed with more width than those occurred at higher longitudes, and this result seems to be the same for latitude. (iii) The dependency of speed is confirmed on the angular distance between the sun-center and source location determined using both the longitude and latitude. (iv) There is no dependency found in the case of acceleration. (v) Among all the three groups of CMEs, the speeds of halo CMEs show more dependency on longitude. The speed of non-halo and non-limb CMEs show more dependency on latitude. The above results may be taken into account in correcting the projection effects of geo-effective CMEs.

• 한국세라믹학회지
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• 제11권2호
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• pp.3-10
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• 1974

For the manufacture of the silver-yellow glass, silver nitrate was used as a colorant in the base glass of $K_2O$-CaO-$SiO_2$ system. The latter in which the optimum condition was revealed showing beautiful yellow color had been selected among others after the preparatory studies to choose base glass. Other base glass systems considered were $Na_2O$-CaO-$SiO_2$, $R_2O$-PbO-$SiO_2$ and $R_2O$-PbO-BaO-$SiO_2$. The color developed on the specimen in various conditions was examined, using spectorphotometer, in term of the changes in absorbance with wavelength in the visible range. Experimental variables were the amount of the colorant and the additives, reheating temperature and time. The additives such as ZnO, BaO, $B_2O_3$ and $As_2O_3$ were added to increase the coloring action. It was observed that as the amount of silver increased in the base glass the absorbance around $410{\mu}m$ showed the increasing tendency, but the width of absorption curve was wider. Hence, the optimum amount of silver appeared to be 0.11~0.12%. It was found that ZnO was effective additive when present about 0.1%, while $As_2O_3$ ineffective rather retarding the coloration. Borax and $BaCO_3$ were proved effective when contained separately, but appeared ineffective when coexisted. Proper reheating temperature and time was ranged 550~$580^{\circ}C$ and 50~60 minutes. The higher the reheating temperature and the longer the reheating time, the absorbance was increased, while the width of absorption curve was wider. The colored glass prepared in the present experimental condition was found to have good water-resistance for the decorative purpose.

• 융합신호처리학회논문지
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• 제11권1호
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• pp.63-73
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• 2010

본 논문에서는 위치 불확실성이 최소화되도록 중첩 초음파 센서 링을 최적 설계하는 방법과 이를 향상된 해상도의 장애물 탐지에 응용하는 방안에 대해 기술하도록 한다. 기본적으로 일군의 초음파 센서들이 일정 간격으로 상호 빔 폭이 중첩되도록 원형으로 배치된다고 가정한다. 첫째, 빔 폭 중첩 상태를 활용함으로써 초음파 센서 고유의 위치 불확실성을 현저히 감소시킬 수 있음을 보인다. 둘째, 반경이 영인 이상적인 중첩 초음파 센서 링에 대해, 위치 불확실성을 나타낼 수 있도록 유효 빔 폭의 개념을 도입하고, 유효 빔 폭을 최소화하기 위해 필요한 초음파 센서의 최적 개수를 구한다. 셋째, 일정 반경의 실제 중첩 초음파 센서 링을 대상으로, 위치 불확실성 정도를 표현하는 설계 지수를 정의하고, 상용 저지향성 초음파 센서를 구성되는 중첩 초음파 센서 링의 최적 설계 예를 제시한다. 넷째, 초음파 센서의 측정 거리로부터 이동로봇 중심 기준 장애물의 위치를 산정하기 위한 기하학적 방법을 기술한다. 마지막으로, 한 쪽이 열린 평면 장애물 탐지 실험을 통해, 자체 제작된 초음파 센서 링의 장애물 탐지 해상도가 향상됨을 입증한다.

• Archives of Plastic Surgery
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• 제36권5호
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• pp.654-659
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• 2009

Purpose: A botulinum toxin type A (BoNT - A) injection has been used as a noninvasive management for lower face contouring since 2000. The aim of this study was to compare reduction rate of lower face width for a longtime according to repeated Botox$^{(R)}$ injections on masseter muscles for lower face contouring procedure. Methods: Forty - five patients were analyzed for single session of Botox$^{(R)}$ injection and 13 patients were evaluated for repeated Botox$^{(R)}$ injections for over two years. Single injection group was tracked regular intervals at 1, 3, 6, 10, 12 months after injection, and repeated injection group was measured at every injection time. Twenty - five to thirty units of Botox$^{(R)}$ was injected into each masseteric muscle at five to six points at the prominent portions of the mandibular angle. Standardized frontal view of digital photographs were analyzed by Adobe Photoshop$^{(R)}$ (version CS3) to measure an reduction rate of lower face width. Results: Reduction rate was 3.7%, 6.9%, 6.2%, 4%, 4% at 1, 3, 6, 10, 12 months post injection each other in single injection group. However, more than 8% reduction rate was found in repeated injection group persistently for more than two years. Conclusion: This study shows that effective duration of Botox$^{(R)}$ injection for lower face contouring is expected to continue over one year clinically. Moreover, repeated injections maintained lower reduction rate consistently for a long time. Therefore, repeated injections on masseter muscles at regular intervals are most effective procedure for lower face contouring.