• Corrosion Science and Technology
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• 제12권4호
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• pp.191-197
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• 2013

This study is the second stage of developing the corrosion control technical manual about unpainted weathering steel bridge with closed box girder structures. This paper contains selection of corrosive sealant to apply into crevice of upper flange, injecting test of sealant at mock-up equipment with various condition, evaluation of experiment result. Through the experiment of injection of sealants into crevice of mock-up equipment, it is proved that the tar sealant injecting corrosion control method is useful to protect corrosion at box girder upper flange corroded by remaning rain water with calcium chloride.

• Corrosion Science and Technology
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• 제12권3호
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• pp.149-157
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• 2013

In corrosion-sensitive areas of exsisting unpainted weathering steel bridges with closed box girder structures. there are some serious local corrosion problems because of rain water or dew water which can not be solved by exsisting maintenance methods. These problems must be controled technically because of bad. influence on the safety of bridge. This study is the first stage of developing the economic corrosion control manual for these local corrosion problems. Through the injection of tar sealant into the crevice of mock-up equipment, it was prooved that the corrosive sealant can be useful to corrosion control at crevice of corrosion sensitive area.

• 설비공학논문집
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• 제19권11호
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• pp.776-781
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• 2007

Optimized capacity of equipments are essential for energy saving and low cost construction and operation. So we must use proper design data for HVAC system design. We investigated for architectural data, equipment capacity, cooling and heating load design criteria of 52 office buildings. Following research results were obtained by carrying out each task. Office building effective area rate is 63%. The average building cooling load of South Korea is $140W/m^2$ and average heating loads in Seoul and Pusan area are $120{\sim}130W/m^2$ and $70{\sim}80W/m^2$. We also analysised HVAC design criteria. Person ratio in effective building area is $0.2person/m^2$, sensitive and latent heat loads of a person are 60W and 65W, light and equipment loads of office buildings are $25W/m^2$ and $20W/m^2$.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.970-977
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• 2014

In this paper, the artificial neural network is used to predict the junction temperature of the IGBT power module, by measuring the temperature sensitive electrical parameters (TSEP) of the module. An experiment circuit is built to measure saturation voltage drop and collector current under different temperature. In order to solve the nonlinear problem of TSEP approach as a junction temperature evaluation method, a Back Propagation (BP) neural network prediction model is established by using the Matlab. With the advantages of non-contact, high sensitivity, and without package open, the proposed method is also potentially promising for on-line junction temperature measurement. The Matlab simulation results show that BP neural network gives a more accuracy results, compared with the method of polynomial fitting.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2173-2187
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• 2022

A 3D thermo-elasto-hydrodynamic model is developed to analyze the sealing performance of a notched mechanical seal applied in the reactor coolant pump. In the model, the generalized Reynolds equation, the energy equation coupled with notch heat balance equation, the heat conduction equations, and the deformation equations of the sealing rings are iteratively solved by the finite element method. The film pressure and temperature distribution are obtained, and the deformation of the sealing rings is revealed to study the mechanism of the notched mechanical seals. A parameterized study is conducted to analyze the sealing performance under different operating conditions. As a comparison, the sealing performance of non-notched seals is also studied. The results show that the hydrostatic effect is dominant in the load-carrying capacity of the fluid film due to the radial mechanical and thermal deformations. The notch can cool the fluid film and influence the thermal deformation of seal rings. The sealing performance is sensitive to the pressure difference, ambient temperature, and rotational speed. It is suggested to set the notches on the softer sealing rings to acquire the greater hydrodynamic effect. Compared with the non-notched, the notched end face holds a better lubrication performance, especially under lower rotational speed.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.395-401
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• 2015

영상의학과의 흉부엑스선 검사에서 감염관리에 대한 기기의 오염 정도를 세균학적으로 확인하고 균을 동정하여 병원감염의 예방과 감염관리방안을 마련하는데 목적이 있다. 영상의학과 흉부 엑스선 검사에서 환자의 기기 접촉부위인 어깨, 손, 턱, 흉부 측면촬영의 손잡이 부위를 70% 이소프로필 알코올로 소독하기 전과 후를 면봉으로 검체를 채취하여 세균을 동정하여 비교하여 분석하였다. 흉부 엑스선 기기에서 소독전의 측면촬영의 손잡이에서 그람 양성의 Staphylococcus가 분리되었다. 최종동정을 위해 노보바이오신 (nobobiocin) 항생제 시험을 실시하여 민감성으로 Staphylococcus epidermidis로 확정하였다. 흉부촬영 기기에서 측면촬영의 손잡이 부위를 소독 전에 Staphylococcus epidermidis 균이 검출되었다. 흉부엑스선 검사에서 기기를 주기적인 소독 및 멸균을 실시하여 병원감염을 예방하는 관리방안을 마련하여야 한다.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1376-1385
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• 2017

This paper proposes a method for estimating the expected frequency of voltage swells caused by asymmetrical faults in a power system. Although voltage swell is less common than voltage sag, repeated swells can have severe destructive impact on sensitive equipment. It is essential to understand system performance related to voltage swells for finding optimal countermeasures. An expected swell frequency at a sensitive load terminal can be estimated based on the concept of an area of vulnerability (AOV) and long-term system fault data. This paper describes an effective method for calculating an AOV to voltage swells. Interval estimation for an expected swell frequency is also presented for effective understanding of system performance. The proposed method provides long-term performance evaluation of the frequency and degree of voltage swell occurrences.

• 한국소음진동공학회논문집
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• 제16권3호
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• pp.307-312
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• 2006

In this study a vibration isolation system with the cradle-type support was designed so as to reduce the transient vibration due to positioning motion of the moving mass on worktable as well as to achieve the desired isolation efficiency on the floor vibration. The design procedure was performed in the two steps. The first step to select appropriate isolators to meet the isolation efficiency, and the second step is to reduce the transient vibration of the worktable by adopting the cradle-type support. After the application of the selected isolators with the cradle-type support to the system it was shown that the required vibration criterion(VC-D) was easily satisfied and that the undesirable transient vibration was reduced remarkably.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.933-939
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• 2000

In this paper we present an overview of the factors and techniques that must be considered in vibration measurements in the floor structures for microelectronics facilities. Normally narrowband vibration spectrum or equivalent signals are suggested as the guide indexes of site vibration phenomina. But it cannot support perfect informations in designing vibration control systems for the vibration sensitive equipment even though the spectrum serves to illustrate the fact that most real vibration environments are dominated by broadband energy as opposed to tonal energy. The major topics cover stiffness in frequency and time domain, acceleration level and modal characteristics from experimental modal analysis as well as narrowband spectrum. The combined signal analysis through the items mentioned above can give better solutions and would be positively recomended to solve the vibration problems on a sort of limited field.

• 한국안전학회지
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• 제15권4호
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• pp.62-68
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• 2000

Static electricity in electronics manufacturing plants causes the economic loss, yet it is one of the least understood and least recognized effects haunting the industry today. Today's challenge in semiconductor devices is to achieve greater functional density pattern and to miniaturize electronic systems of being more fragile by electrostatic discharges(ESD) phenomena. As the use of automatic handling equipment for static-sensitive semiconductor components is rapidly increased, most manufacturers need to be more alert to the problem of ESD. One of the most common causes of electrostatic damage is the direct transfer of electrostatic charge from the human body or a charged material to the static-sensitive devices. To evaluate the ESD hazards by charged human body and devices, in this paper, characteristics of electrostatic attenuation in domestic semiconductor devices is investigated and the voltage to cause electronic component failures is investigated by field-induced charged device model(FCDM) tester. The FCDM simulator provides a fast and inexpensive test that faithfully represents ESD hazards in plants. Also the results obtained in this paper can be used for the prevention of semiconductor failure from ESD hazards.