The performance characteristics of a lead acid battery are investigated with the content of Sodium Perborate Tetrahydrate (SPT, NaBO3·4H2O) in a positive plate active material. SPT, which reacts with water to form hydrogen peroxide, is applied as an additive in the positive plate active material to increase adhesion between the substrate (positive plate) and the active material; this phenomenon is caused by a chemical reaction on the surface of substrate. A positive plate with the increasing content of SPT is prepared to compare its properties. It is confirmed that the oxide layer increases at the interface between the substrate and the active material with increasing content of SPT; this is proven to be an oxide layer through EDS analysis. Battery performance is confirmed: when SPT content is 2.0 wt%, the charging acceptance and high rate discharge properties are improved. In addition, the lifetime performance according to the Standard of Battery Association of Japan (SBA) S0101 test is improved with increasing content of SPT.

NKN [(Na,K)NbO3] is a candidate lead-free piezoelectric material to replace PZT [Pb(Zr,Ti)O3]. A single crystal has excellent piezoelectric-properties and its properties are dependent of the crystal orientation direction. However, it is hard to fabricate a single crystal with stoichiometrically stable composition due to volatilization of sodium during the growth process. To solve this problem, a solid solution composition is designed (Na,K)NbO3-Ba(Cu,Nb)O3 and solid state grain growth is studied for a sizable single crystal. Ceramic powders of (Na,K)NbO3-M(Cu,Nb)O3 (M = Ca, Sr, Ba) are synthesized and grain growth behavior is investigated for different temperatures and times. Average normal grain sizes of individual specimens, which are heat-treated at 1,125 oC for 10 h, are 6.9, 2.8, and 1.6 m for M = Ca, Sr, and Ba, respectively. Depending on M, the distortion of NKN structure can be altered. XRD results show that (NKN-CaCuN: shrunken orthorhombic; NKN-SrCuN: orthorhombic; NKN-BaCuN: cubic). For the sample heat-treated at 1,125 oC for 10 h, the maximum grain sizes of individual specimens are measured as 40, 5, and 4,000 m for M = Ca, Sr, and Ba, respectively. This abnormal grain size is related to the partial melting temperature (NKN-CaCuN: 960 oC; NKN-SrCuN: 971 oC; NKN-BaCuN: 945 oC).

The number of aged bridges is increasing so that bridges over 30 years old account for about 11% of all bridges. Consequently, the development of a seismic performance evaluation method that considers the effects of ageing is essential for a seismic retrofitting process for improvement of the seismic safety of existing old bridges. Assessment of the damage situation of bridges after the recent earthquakes in Korea has been limited to the bearings, anchor, and concrete mortar on piers. The purpose of this study is to evaluate the seismic responses of PSC box girder bridges by considering the ageing effect of rubber bearings (RBs) and lead-rubber bearings (LRBs). The modification factor proposed by AASHTO is used to take into account the ageing effect in the bearings. PSC box girder bridges with RBs and LRBs were 3D modeled and analyzed with the OpenSEES program. In order to evaluate the ageing effect of RBs and LRBs, 40 near fault and 40 far field records were used as the input earthquakes. When considering the effect of ageing, the displacement responses and shear forces of bridge bearings (RBs and LRBs) were found to increase mostly under the analytical conditions. It was shown that the effect of ageing is greater in the case of RBs than in the case of LRBs.

The tendency to use a probabilistic design method rather than a deterministic design method for the design of nuclear power plants (NPPs) will increase because their safety should be considered and strictly controlled in relation to various causes of damage. The distance between a seismically isolated NPP structure and a moat wall is called the clearance to stop. The clearance to stop is obtained from the 90th percentile displacement response of a seismically isolated NPP subject to a beyond design basis earthquake (BDBE) in the probabilistic design method. The purpose of this study is to analyze the effects of heating and buckling effects on the 90th percentile displacement response of a lead-rubber bearing (LRB) subject to a BDBE. The analysis results show that considering the heating and buckling effects to estimate the clearance to stop is conservative in the evaluation of the 90th percentile displacement response. If these two effects are not taken into account in the calculation of the clearance to stop, the underestimation of the clearance to stop causes unexpected damage because of an increase in the collision probability between the moat wall and the seismically isolated NPP.

In case of worm reducer, the worm and worm wheel are the significant design elements. Most of the worm and worm wheel are being importer and assembled because that the localization is inadequate. As the demand increases and the necessity of localization and precision grows, to develop them is now more important things. In this study, we conducted the design, manufactured prototype and performance evaluation for worm reducer for dual lead 5.2:1 servo motor. The worm reducer is analyzed design reliability by finite element method. The performance evaluation for manufactured prototype worm reducer was conducted on the backlash, operation temperature and contact efficiency with/without load and satisfied for the all test items.

A lead-free bulk ceramic having a chemical formula Ba0.8Ca0.2(Ti0.8Zr0.1Ce0.1)O3 (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

Pb(Zr,Ti)O3 (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. (K,Na)NbO3 (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, (Na,K)NbO3-Ba(Cu,Nb)O3 (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKNBCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan δ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and 20 μC/cm2.

당대는 축적된 연유기술을 바탕으로 화려한 삼채도기 문화를 꽃피운 시기였다. 당대의 연유도기는 이전의 단색 연유기술과 달리 다양한 색상의 구현이 가능했으며, 세 가지 색 이상을 혼용하기도 하여 시각적인 화려함이 극대화되었다. 소위 당삼채라는 당대의 대표적 연유도기는 7세기 중반 盛唐 이후 크게 유행하였다. 주로 부장품인 明器로 활용되었으나 출토 상황에 의하면 일상생활에서도 적지 않게 사용되고 있음이 확인된다. 오늘날 고고학적 발굴 성과에 의하면 당대의 연유도기는 화북 및 화남 등 여러 窯場에서 생산되었으며, 중국 내 소비와 함 께 동아시아는 물론 동남아시아와 서아시아로까지 널리 수출되어 활발한 소비가 이루어졌다. 본 연구에서 당대의 주력 생산품이었던 당대 연유도기의 생산과 소비, 그리고 수출에 관한 그간 학계의 연구성과를 소개하고 관련 논제들을 검토해보고자 하였다. 아울러 그간 동아 시아에 비해 덜 주목되었던 동남아시아와 서아시아 지역의 출토 사례를 중심으로 해외 전파와 그 의미를 살펴보고자 하였다. 그 결과 몇 가지의 결론을 내릴 수 있었다. 먼저 여러 발굴 성과를 토대로 살펴보면, 당대 厚葬문화 덕에 初唐부터 이미 삼채 도용이 대규모로 생산되었고, 이는 황족묘나 고관대작 분묘 출토품을 통해 어렵지 않게 추정이 가능하다. 하지만 한 편으로 섬서 서안의 中堡村이나 하남성의 張思忠夫婦墓 등의 출토 예를 통해, 無官職이거나 중상급의 평민계층 사이까지 폭넓게 향유되었음을 알 수 있어 이는 당대의 전형적 부장문 화임을 알 수 있었다. 그러나 8세기 중엽 안녹산의 난(755~763) 이후, 화려한 당삼채의 생산이 종식되고 대 신 백유녹채의 생산이 활발해졌다. 이는 성당기의 삼채와는 성격을 달리하는 새로운 채유 도기로 성당시기 당삼채는 부장용 명기의 성격이 강했으나, 9세기 백유녹채도기는 실용기에 가깝다. 그런데 이 백유녹채도기의 제작을 촉구한 역사적 배경은 바로 8세기 후반 이후 바닷길을 통해 이루어진 서아시아, 즉 이슬람제국과의 교역이라고 할 수 있다. 특히, 9세기 폭발 적으로 증가한 이슬람과의 도자무역은 결과적으로 이슬람 시장과 영향력에 대한 당나라의 태도에 기인한 것이라 판단된다. 이는 단순히 동방의 연유 도기가 이슬람권에 수출된 것이 아니라 이슬람권의 기호를 중국 측이 수용한 결과로 보아야 할 것이다.

This study suggests a model of production information system that can reduce manufacturing lead time and uniformize quality by using DNC S/W as a part of constructing production information management system in the industrial field of the existing marine engine block manufacturing companies. Under the effect of development of this system, the NC machine interface device can be installed in the control computer to obtain the quality information of the workpiece in real time so that the time to inspect the process quality and verify the product defect information can be reduced by more than 70%. In addition, the reliability of quality information has been improved and the external credibility has been improved. It took 30 minutes for operator to obtain, analyze and manage the quality information when the existing USB memory is used, but the communication between the NC controller computer and the NC controller in real time was completed to analyze the workpiece within 10 seconds.

본 연구에서는 국내 유통 중인 농산물 9품목(n = 578)에 대한 납과 카드뮴 함량을 조사하고 이들의 섭취로 인한 위해성을 평가하고자 하였다. 납과 카드뮴의 함량은 마이크로웨이브 분해 후 ICP-MS로 분석하였다. 조사대상 농산물의 납 평균 함량은 각각 보리 0.014 mg/kg, 완두콩 0.010 mg/kg, 강낭콩 0.008 mg/kg, 녹두 0.006 mg/kg, 파인애플 0.008 mg/kg, 살구 0.016 mg/kg, 매실 0.015 mg/kg, 자두 0.021 mg/kg, 대추 0.019 mg/kg이었고, 카드뮴 평균함량은 보리 0.017 mg/kg, 완두콩 0.004 mg/kg, 강낭콩 0.007 mg/kg, 녹두 0.005 mg/kg, 파인애플 0.001 mg/kg, 살구 0.002 mg/kg, 매실 0.002 mg/kg, 자두 0.002 mg/kg, 대추 0.003 mg/kg이었다. 모든 시료의 납, 카드뮴 함량은 EU, CODEX 및 국내 기준보다 낮은 수준이었다. 조사 대상 농산물에 대한 납, 카드뮴의 인체노출량을 산출한 결과, 납은 잠정주간섭취허용량(PTWI, 25 μg/kg b.w./week)의 0.067%, 카드뮴은 월간잠정섭취허용량(PTMI, 25 μg/kg b.w./month)의 0.28%이었다. 이상의 결과는 조사 대상 농산물의 납, 카드뮴 오염도와 이들의 섭취에 의한 위해성이 모두 낮은 수준이라는 것을 보여준다.