• 치과방사선
• /
• 제23권1호
• /
• pp.95-100
• /
• 1993

The author observed a case of osteogenic sarcoma in a 11-year-old female with complaint of painful swelling on face in right side. The observed results were as follows: 1. Large hematoma was obsered, and patient complanited painfull swelling on c/c site. 2. Predisposing factor of osteogenic sarcoma was not clear, but patient had history of extraction before patient visiting infirmary of our dental collage. 3. Serologic findings were not specific, and serum alkaline level was normal. 4. Radiographic findings were as follows: ① Diffuse faint radiopacity in the lesion ② Bony destruction and increased radiopaciy in right antrum ③ Displacement of multiple teeth on involved area(i. e ;＃12, 15. 55, 16, 17, 18), ④, Increased periodontal space in singel tooth(＃13) ⑤Destruction of bony crypt on involved teeth(＃13, 14, 15, 17, 18) ⑥ Loss of lamina dura of three teeth in involved area(＃11, 12, 16) 5. Computed tomographic findings were as follows: ① Large calcific and hetergenous component mass in the Rt. maxillary sinus, and this mass extending to Rt. maxilla, alveolar bone, ethmoid sinus. ②, Soft tissue bulging into Rt. side nasal cavity and oral cavity. ③ Bone destruction of maxillary sinus wall and Rt. alveolar bone.

• Journal of Periodontal and Implant Science
• /
• 제35권1호
• /
• pp.177-185
• /
• 2005

The purpose of the study was to investigate the influence of an endodontic infection on presence of furcation involvement in periodontally-involved mandibular molars. All first and second mandibualr molars in 45 patients were selected if at least one was root-filled or had a possible periapical radiolucency. The sample consisted of patients from a referral population at a periodotnal clinic which represented an adult population with a mean age of 47.5 years (range 31 to 63) For mandibular molars with periapical destruction at both roots, frequency of horizontal furcation depth ${\geqq}$ 3 mm was significantly more compared to teeth without periapical destruction. Mean periodontal probing depth was significantly greater at mandibular molars with periapical destruction. It is suggested that a root canal infection in periodontitis-involved molars may potentiate periodontitis progression by spreading of endodontic pathgens through patent accessory canals and dentinal tubules. In conclusion, an endodontic infection in mandibular molars was found to be associated with additional attachment loss in the furcation area, and may thus be considered to be one of several risk factors influencing the prognosis of molars in periodontitis-prone patients.

• 한국경영과학회지
• /
• 제27권1호
• /
• pp.33-51
• /
• 2002

A fully connected Artificial Neural Network (ANN) contains many connections. Compared to the pruned ANN with fewer connections, the fully connected ANN takes longer time to produce solutions end may not provide appropriate solutions to new unseen date. Therefore, by reducing the sloe of ANN, we can overcome the overfitting problem and increase the computing speed. In this research, we reduced the size of ANN by destroying the connections. In other words, we investigated the performance change of the reduced ANN by systematically destroying the connections. Then we found the acceptable level of connection-destruction on which the resulting ANN Performs as well as the original fully connected ANN. In the previous researches on the sloe reduction of ANN, the reduced ANN had to be retrained every time some connections were eliminated. Therefore, It tool lolly time to obtain the reduced ANN. In this research, however, we provide the acceptable level of connection-destruction according to the size of the fully connected ANN. Therefore, by applying the acceptable level of connection-destruction to the fully connected ANN without any retraining, the reduced ANN can be obtained efficiently.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.75-78
• /
• 2006

Disposal of highly toxic wastes like polychlorinated biphenyls (PCBs) is very difficult. These substances create a growing mountain of problematic waste that has to be disposed properly. Conventional technologies that are based on common burning(rotary kiln, ${\sim}1100^{\circ}C$) and plasma technology(${\sim}10000^{\circ}C$) do not satisfy important conditions. for example, complete combustion of the toxic waste and the price of waste disposal. The combustor like a rocket engine is operated at relatively high pressure(${\sim}15$ bar) and relatively high temperature(>$3000^{\circ}C$) that are ideal for the complete destruction of extremely toxic substances. In this study, test compound($_o-DCB$) was dissolved in kerosine with a concentration of 10%. Pure gas oxygen was used as an oxidant. Analysis showed that the destruction efficiency achieved for ${o}-DCB$ was 99.9999% or better. The results show that a combustor based on liquid propllant rocket technology is a validated tool for the disposal of highly toxic waste, and a good alternative technology when applied to the destruction of extremely toxic wastes.

• Applied Science and Convergence Technology
• /
• 제24권2호
• /
• pp.27-32
• /
• 2015

We analyzed the destruction patterns of a turbo-molecular pump (TMP) resulting from its sudden exposure of a foreline to the atmospheric pressure due to a destruction of the foreline connecting clamp of an ICP dry etcher for 300 mm wafers during high-vacuum operation ($5{\times}10^{-6}$ Torr). Unlike in the case of view port's breakage, the TMP's rotor module was crashed inside the chamber. The primary damage resulted from the collision of the blades and stators, and the secondary damage resulted from the breaking of the rotor - driving shaft assembly. The fixing screws of the rotor and axial shaft were bent and broken when the TMP controller output the maximum current even after the crash event. Electrical power consumption analysis of the TMP power controller confirmed it. The stress distributions were analyzed by a finite element method using CFD-ACE+ multi physics software. Rotating inertia of each parts and kinetic energies were calculated as well. 68% of the rotational kinetic energy is deposited by the rotor - shaft module.

• 분석과학
• /
• 제13권5호
• /
• pp.646-651
• /
• 2000

$TiO_2$ 촉매 하에 염료 Mordant Yellow-12를 광촉매 분해하였다. 이때 사용한 광원은 각각 15-W, 21-W와 26-W 형광 램프를 이용하였다. 분해 정도는 자외선-가시광선 분광기와 pH 메타를 이용하였다. 실험 결과 반응 1시간 후에 각 광원에 따라 각각 17%, 24%, 34% 이상의 분해를 보였고 완전히 분해되는데는 각각 3, 4, 5시간 걸렸다. pH의 변화는 흡광도의 변화와 같이 급격한 결과를 나타내지 않았다. 분해 반응 속도는 15-W 보다 26-W에서 2배의 빠를 분해 반응속도를 보였다.

• 한국대기환경학회지
• /
• 제26권6호
• /
• pp.624-632
• /
• 2010

Perfluorocarbons (PFCs) are widely used in semiconductor industry. These gases need to be removed efficiently because of their strong absorption of infrared radiation and long atmospheric lifetimes which cause the global warming effect. To destruct $CF_4$, a waterjet gliding arc plasma was designed and manufactured. The highest $CF_4$ destruction showed at waterjet plasma case, compared to plasma discharge only or water scrubber only, respectively. In addition, it could be known that the $CF_4$ destruction should be associated with the electron and OH radicals. The operating conditions such as waterjet flow rate, initial $CF_4$ concentration, total gas flow rate, specific energy input were investigated experimentally using a plasma waterjet scrubber. Through the parametric studies, the highest $CF_4$ destruction of 94.5% was achieved at 0.2% $CF_4$, 2.1 kJ/L SEI, 20 L/min total gas flow rate and 18.5 mL/min waterjet flow rate.

• Bulletin of the Korean Chemical Society
• /
• 제28권8호
• /
• pp.1383-1388
• /
• 2007

Recently, the semiconductor and display industries have tried to reduce the emissions of perfluorocompounds (PFCs) from the globally environmental regulation. Total amount of PFC emission can be calculated from the flow rate and the partial pressures of PFCs. For the precise measurement of PFC emission amount, the mass flow controlled helium gas was continuously injected into the equipment of which scrubber efficiency is being measured. The partial pressures of PFCs and helium were accurately measured using a mass spectrometer in each sample extracted from inlet and outlet of the scrubber system. The flow rates are calculated from the partial pressures of helium and also, PFC destruction and removal efficiency (DRE) of the scrubber is calculated from the partial pressure of PFC and the flow rate. Under this method, the relative expanded uncertainties of the flow rate and the partial pressures of PFCs are ± 2% (k = 2) in case the concentrations of NF3 and SF6 are as low as 100 μmol/mol.

• Korean Chemical Engineering Research
• /
• 제50권2호
• /
• pp.343-347
• /
• 2012

충전형 저온 플라즈마 반응기 내에서의 가스 상 시안화합물의 분해특성을 반응기로 투입되는 방전 전력, 시안화합물의 유입농도, 운반기체인 공기의 습도 및 반응기 내의 충전물질 등을 변수로 연구하였다. 저온플라즈마 방전의 경우 시안화합물들의 분해는 트리클로로에틸렌에 비하여 상대적으로 매우 낮은 효율을 보였다. 그러나 플라즈마 방전 영역에 알루미나 또는 백금/알루미나 구슬을 충전한 경우 분해효율이 크게 높아졌으며 이는 플라즈마 반응과 더불어 백금/알루미나의 촉매작용에 의한 촉매 반응이 동시에 작용함에 기인한 것으로 판단된다.

• 한국공작기계학회논문집
• /
• 제10권6호
• /
• pp.102-108
• /
• 2001

To prevent green house effect and destruction of an ozone layer, an ozone destruction potential(OBP) must be zero and a refrigerant for low global warming potential(GWP) is needed. HFC-l34a, in which hydrogen is mixed instead of chlorine is a refrigerant used for automobile conditioners and its destruction potential is ecologically zero. However, it is not consid- ered as a perfect substitutive refrigerant as its GWP is high. It is studied refrigerant mixtures in which HFC-l52a and $CF_3 I$ in HFC-l52a with low GWP and zero ODP are mixed by experimentally and concluded as follows: 1) With the variation of speed of compressor outside temperature and flow rate, 7he heat of evaporator and compressor and coefficient of perfor- mance was varied, and influenced the air conditioner. 2) The pressure of evaporator was decreased with increasing the speed of compressor and the pressure of evaporator with the refrigerant HFC-l52a was higher 24% than that of azotrope refrigerant mixed with $CF_3 I$