• 헤리티지:역사와 과학
• /
• 제45권1호
• /
• pp.102-121
• /
• 2012

연천 합수리 유적의 7호 주거지와 2호 주거지 및 6호 주거지에서 출토된 신석기 시대 토기 2점 (YCP-1, YCP-2), 청동기 시대 토기 2점 (YCP-3, YCP-4), 원삼국 시대 토기 4점 (YCP-5~8)과 토양 1점(YCRM)을 분석하여 토기와 토양의 동질성을 확인하고 토기의 소성온도를 규명하였다. 화학적 성분분석 결과, 토양(YCRM)은 YCP-1, YCP-3, YCP-5, YCP-6, YCP-7, YCP-8의 토기와 동일한 거동 특성을 보였다. 반면, YCP-2와 YCP-4는 활석과 녹니석의 영향으로 MgO의 부화가 나타나 다른 토기나 토양과는 다른 거동특성을 보였다. 또한 흡수율과 비중, 조직특성과 XRD 분석결과를 바탕으로 소성온도를 추정해 보면, YCP-7와 YCP-8은 $870^{\circ}C$이상, YCP-2와 YCP-4의 경우 $800^{\circ}C$이하, YCP-1과 YCP-3, YCP-5, YCP-6은 $800{\sim}870^{\circ}C$의 소성온도를 갖는 것으로 판단된다. 광물 분석결과, 토양은 연천 합수리 유적지 일대의 지질을 반영하며, 토기와의 유사성이 있으므로 유적주변에서 채취되어 토기의 원료물질로 사용된 것으로 추정된다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2007년도 춘계학술대회 논문집
• /
• pp.71-74
• /
• 2007

Substitution of the stacked antenna for the normally pressed antenna in the mobile phone was tried for the purpose of decreasing its size. However, reduced size resulted in the difficulties obtaining the targeted characteristics with the bandwidth over 70MHz. The cross-section of the vias in the low temperature co-firing ceramics process was studied to find out effects on the bandwidth characteristics. Circular and rectangular cross-section of the via beneath different types of antenna patterns were simulated. Better bandwidth characteristics were acquired for the larger diameter of the circular section and for the rectangular section as the cross-section area increased. From the viewpoint of the shape of the cross-section, rectangular area showed better characteristics than the circular area with the same longest length in the cross-section.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
• /
• pp.282-292
• /
• 2006

Various kinds of coals are supplied for coal fired power plants as the coal market situations are fluctuated with the high prices of oil and coals over the world. The quality of coal is decreasing as coal consumption increased and some specifications of coals are out of boiler design criteria. It could make combustion troubles such as coal clogging, spontaneous combustion, coal firing in the coal handling equipments, ash slag and clinker issues, etc. This paper covers combustion troubles, issues and countermeasures in the biggest coal fired power plant in Korea.

• 한국정보통신학회논문지
• /
• 제7권4호
• /
• pp.725-729
• /
• 2003

본 논문에서는 LCD 후면 광원용 한 쌍의 형광층, 방전용기 및 대향전극을 갖는 무수은 평판형광램프에 대하여 연구하였다. 구동 전압이 인가되면 균일한 방전이 램프 전체에 걸쳐서 발생한다. 방전개시전압은 가스 압력에 따라 증가한다. 이와 같은 경향은 방전 가스 압력의 증가에 의한 평균자유행정의 감소에 기인된 것으로 생각된다. 녹색 발광 평판형광램프에서 최대 2700[cd/m2]의 휘도를 얻었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 B
• /
• pp.1091-1093
• /
• 2001

The power semiconductor is widely used in the power plant or industrial field because of genealization and enlargement. It has been controlled and operated according to its own control method. Especially in case of Power plant, it plays a major role in AVR(Automatic Voltage Regulator) or electro chlorination control circuits. Generally, they used in Analog control system at above field. But each SCR current value is different because of load unbalance or switching characteristic variations, it may cause power plant unit trip or system disorder according to SCR element burn out or bad operating condition. Therefore, in this paper a development of 3 phase current balance control algorithm is described. it gets over the past analog control system limit, controls SCR gate firing angle for 3 phase current balance.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.351-355
• /
• 2003

In this paper, a new barrier rib forming method of embossed barrier rib (EBR) formation process for the PDP rear panel was introduced. The process is mainly composed of green sheet fabrication, lamination of the green sheet on the rear glass panel having data electrodes, and roll embossing followed by firing. The EBR process has two advantages over the conventional barrier rib forming methods. One is the process requires less equipment investment than the conventional methods by about 20% of the current rear panel fabrication equipment investment owing to the simplified fabrication process. The other advantage is its reduced rear panel manufacturing cost by eliminating the time consuming and complicated processes and waste of materials in the conventional methods. In this study, general procedure of EBR fabrication process is described and the characteristics of prototype PDP using EBR panel are discussed.

• 전기학회논문지
• /
• 제65권1호
• /
• pp.103-107
• /
• 2016

In general, the voltage stability of induction generator is lower than synchronous generator. Induction generator has a number of advantages over the synchronous generator on the side of price and maintenance. So Induction generator has been applied to the small hydroelectric power of low output. Induction generator usually generates a high current during grid connection. The high current that occurs during grid connection can cause a voltage drop in the system. In order to increase the supply of the induction generator, it is necessary to propose a method of reducing high current. This paper proposes some method of the soft start to reduce voltage drop caused by the large starting current. soft-start method has high voltage drop effect than direct start method, control of firing angle can be increased the voltage drop effect.

• Journal of the Korean Statistical Society
• /
• 제7권1호
• /
• pp.61-80
• /
• 1978

This paper presents general solutions for stochastic square duels with continuous interfiring times and various firing strategies such as standby (S), concentrated (C), seperated (I) and random (R) firings. Analysis of these square duels with negative exponential interfiring times and equivalent values of rates of fire and single shot kill probabilities reveal three important facts: i) Strategy (C) is advantageous against the opponent's strategy (S) and the advantage becomes more pronounced for lower values of single shot kill probabilities. ii) Strategy (I) is always better than strategy (C) no matter which of (C) and (I) the opponent uses and its relative advantege increases to a quarter as single shot kill probabilities increase to one but decreases to zero as they go to zero. iii) However, strategy (I) has no advantage over strategy (C) for small values of single shot kill probabilities. In this paper, square duels with strategies (C) and (I) are based on the assumptions that duelists are homogeneous and both duelists of one side fire simultaneously. The problem of relaxing these assumptions and extension of square ($2 \times 2$) duels to more general ($m \times n) duels are now being investigated.

• 한국세라믹학회지
• /
• 제32권11호
• /
• pp.1255-1261
• /
• 1995

Mullite-spinel-zirconia composites were prepared by reaction sintering of calcined alumina and magnesia, and zircon powders. The influence of calcining temperature on densification processes and on mechaical properties of subsequently sintered compacts was investigated. The mullite was formed by the reaction of $\alpha$-Al2O3 and amorphous SiO2 at firing temperatures over 141$0^{\circ}C$. The mullitization proceeded more rapidly in the specimen calcined at 110$0^{\circ}C$ than at either 120$0^{\circ}C$ or 130$0^{\circ}C$. Microstructures before and after the mullitization (or mullite dissociation) showed different morphologies, and their effects on mechanical properties were significant. The flexural strength and fracture toughness of the specimen calcined at 130$0^{\circ}C$ and subsequently fired at 145$0^{\circ}C$ were 316 MPa and 4.2Mpa.m1/2, respectively.

• 전기학회논문지
• /
• 제58권2호
• /
• pp.217-224
• /
• 2009

This paper presents a new AC/DC converter scheme for HVDC system to achieve a high power factor operation. The new AC/DC converter consists of two 12-pulse bridge converters in series: the primary and auxiliary converters. Ignition angles of the main and auxiliary converters are controlled independently to maintain the nominal DC voltage and control auxiliary voltage. The resulted DC voltage obtained by superimposing the above two phase modulated voltages can be controlled very rapidly over a wide range, and a high power factor operation is achieved. Performance improvements in power factor and harmonic distortion are validated by theoretic derivations and experiments with prototype HVDC system. With the proposed converters, investment for reactive power compensation and filter in HVDC system can be saved significantly.