• 한국전기전자재료학회논문지
• /
• 제21권1호
• /
• pp.29-34
• /
• 2008

In this paper, we investigated electrical and physical characteristics of nickel silicide using rare-earth metals(Er, Yb, Tb, Dy), Incorporated Ytterbium into Ni-silicide is proposed to reduce work function of Ni-silicide for nickel silicided schottky barrier diode (Ni-silicided SBD). Nickel silicide makes ohmic-contact or low schottky barrier height with p-type silicon because of similar work function (${\phi}_M$) in comparison with p-type silicon. However, high schottky barrier height is formed between Ni-silicide and p-type substrate by depositing thin ytterbium layer prior to Ni deposition. Even though the ytterbium is deposited below nickel, ternary phase $Yb_xN_{1-x}iSi$ is formed at the top and inner region of Ni-silicide, which is believed to result in reduction of work function about 0.15 - 0.38 eV.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
• /
• pp.14-22
• /
• 1999

Daylight collapse have been occurred by about 6.$^{0}$ m deep at ground surface which connected to the ground surface and excessive overbreak have been occurred by the space and height of 3.$^1$~6.$^2$m at crown head part of the tunnel during tunnelling of lower-half part after completing upper-half part on tunnelling of a phyllite mountain by NATM method at the construction work of two way-double track national road. This study is a successful illustration case of earth improvement by confirming structural safety of the tunnel in a whole through solving the cause of the tunnel collapse and the work have completed successfully through applying such earth strengthening method as cement mortarㆍcement milk injection, S.G.R, steel pipe reinforced multi-step grouting etc.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
• /
• pp.157-157
• /
• 2008

As the minimum feature size of semiconductor devices scales down to nano-scale regime, ultra shallow junction is highly necessary to suppress short channel effect. At the same time, Ni-silicide has attracted a lot of attention because silicide can improve device performance by reducing the parasitic resistance of source/drain region. Recently, further improvement of device performance by reducing silicide to source/drain region or tuning the work function of silicide closer to the band edge has been studied extensively. Rare earth elements, such as Er and Yb, and Pd or Pt elements are interesting for n-type and p-type devices, respectively, because work function of those materials is closer to the conduction and valance band, respectively. In this paper, we increased the work function between Ni-silicide and source/drain by using Pd stacked structure (Pd/Ni/TiN) for high performance PMOSFET. We demonstrated that it is possible to control the barrier height of Ni-silicide by adjusting the thickness of Pd layer. Therefore, the Ni-silicide using the Pd stacked structure could be applied for high performance PMOSFET.

• 대한인간공학회지
• /
• 제25권2호
• /
• pp.11-22
• /
• 2006

The muscular-skeletal disorders(MSDs) that have become a major issue recently in Korean industrial safety area are mainly caused by manual material handling task. The objective of this study is to provide scientific data for the establishment of work safety standard for Korean workers through the experiments of lifting task under various conditions, in order to prevent the muscular-skeletal disorders in the industrial work site. Eight male college students were recruited as participants. Three different lifting frequencies(1, 3, 5 lifts/min) and three twisting angles(including the sagittal plane and two asymmetric angles; i.e., 0°, 45°, 90°) for symmetric and asymmetric tasks, respectively, with three lifting range from floor to knuckle height, knuckle to shoulder, floor to shoulder height for one hour's work shift using free style lifting technique were studied. The maximum acceptable weight of load(MAWL) was determined under the different task conditions, and the oxygen consumption, heart rate, and RPE were measured or recorded while subjects were lifting their MAWLs. The results showed that: (1) The MAWLs were significantly decreased as the task frequency and task angle increased.; (2) The heart rate, oxygen consumption, RPE significantly increased with an increase in lifting frequency although maximum acceptable weight of lift decreased.; (3) The highest heart rate and oxygen consumption was recorded at the lifting range of floor to shoulder, followed by floor to knuckle and knuckle to shoulder.; (4) The RPE value showed that subjects perceived more exertion at the high frequency rate of lifting task and lifting range of floor to shoulder height. (5) The modeling for MAWL using isometric strength, task angle and lifting frequency were developed. It is expected that use of the results provided in this study may prove helpful in reducing MMH hazards, especially from lifting tasks for Korean, and can be used as a basis for pre-employment screening.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제10권3호
• /
• pp.203-212
• /
• 2010

In this paper, we present an analytical model for the first eigen energy level ($E_0$) of the carriers in the inversion layer in present generation MOSFETs, having ultrathin gate oxides and high substrate doping concentrations. Commonly used approaches to evaluate $E_0$ make either or both of the following two assumptions: one is that the barrier height at the oxide-semiconductor interface is infinite (with the consequence that the wave function at this interface is forced to zero), while the other is the triangular potential well approximation within the semiconductor (resulting in a constant electric field throughout the semiconductor, equal to the surface electric field). Obviously, both these assumptions are wrong, however, in order to correctly account for these two effects, one needs to solve Schrodinger and Poisson equations simultaneously, with the approach turning numerical and computationally intensive. In this work, we have derived a closed-form analytical expression for $E_0$, with due considerations for both the assumptions mentioned above. In order to account for the finite barrier height at the oxide-semiconductor interface, we have used the asymptotic approximations of the Airy function integrals to find the wave functions at the oxide and the semiconductor. Then, by applying the boundary condition at the oxide-semiconductor interface, we developed the model for $E_0$. With regard to the second assumption, we proposed the inclusion of a fitting parameter in the wellknown effective electric field model. The results matched very well with those obtained from Li's model. Another unique contribution of this work is to explicitly account for the finite oxide-semiconductor barrier height, which none of the reported works considered.

• 한국안전학회지
• /
• 제29권5호
• /
• pp.29-34
• /
• 2014

The live line working is inherently dangerous as the workers have to work under the risk of electrical shock and most of works are carried out at height. The live line working need the some specific techniques and higher level safety measures such as a risk assessment to carry out works safely, but the electrical construction companies performed live-line working are usually small-sized companies. They have less capacity to have own safety management system. This study intended to conduct an in-depth analysis on the cause of electric shock accidents to provide basic data for policy proposing taking into considering the past eleven years for a long-term plan. And the aim of this study is to propose the policy about the equipment performance standards and/or worker's safety standards to revise the standards for preventing electric shock accidents, moreover, co-relation of the electrical work order form and on safety workings, especially electrical construction company/work.

• 대한인간공학회지
• /
• 제35권1호
• /
• pp.1-10
• /
• 2016

Objective: This study aimed to find good design for summer functional farm shoes under the agricultural environment and working characteristics, which can help safe farm work and further promote the efficiency of working. Background: Most accidents at farms were overturn accidents caused by slipping or falling, and it was found that the main factors which caused the overturn accidents were inappropriate work shoes for the working conditions. These inappropriate work shoes often cause overturn accidents in the rural areas with steep paths. Method: A survey on work shoes was conducted with 174 farmers, and the outcome of this survey was used to find problems of work shoes and improvement ideas for the design of work shoes which can be used at farms. Results: Regarding the form of farm shoes, the ankle height was set at 6 inches to prevent the bending of the ankle and the inflow of foreign substances. The size and groove of the pattern of the outsole were extended to prevent catching of foreign substances. In the upper part, polyurethane and cordura were used in combination to secure air permeability, which was pointed out as the reason for the discomfort during the work wearing existing work shoes. Conclusion: Since farmers felt discomfort with the shoes which they were currently wearing, this study suggested a design of farm shoes by analyzing the important matters of the work shoes in development in order to improve such discomfort. Application: This study can help develop farm shoes that would practically ease farmers' burden of working at farm worksites and keep them safe.

• 국제학술발표논문집
• /
• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
• /
• pp.229-233
• /
• 2011

Recently, the scale of buildings has been increasing because of the high-rise trend and complexity of underground spaces. A significant number of steel structures have therefore been adopted for building construction. Since workers need to work in high places to install steel beams, many industrial accidents easily occur during steel-frame work. Furthermore, considering the increasing trend of building steel structures, the safety of the workers during the steel beam erection work is of concern. To improve the safety, a new type of joint, located between the steel column and beam, which can eliminate the need for working at the elevated height during steel beam erection has been developed in Korea. Using the newly developed technology in the construction field, the safety performance needs to be evaluated. This study presented the safety evaluation approach for the newly developed technology from the literature review, and applied the method to a self-supported steel joint. The result showed that applying the self-supported steel joint improved the safety of the steel erection work in terms of working posture, working environment, and risk exposure time.

• The Journal of Korean Physical Therapy
• /
• 제18권6호
• /
• pp.67-75
• /
• 2006

Purpose: Many kinds of musculoskeletal disease and symptom are caused by the longtime computer works. However, trapezius muscle tonus has not been established in regarding to keyboard height during typing. Therefore, this study is to evaluate the relationship between trapezius muscle tonus and the height of keyboard while typing, controling for the postures of neck, Lumbar, cervical vertebra. Methods: The experimental height of keyboard was set at elbow height, 3cm higher, 6cm higher, 9cm higher, than elbow. We studied trapezius tonus with the mean value for 2 minutes by EMG in 15 males and 15 females worker of hospital in seoul, who did not have a history of muscle disease, neurological signs, nerve damage. Results: In this experimental, as the height of the keyboard went up, the trapezius tonus significantly increased with shoulder abduction of brachium. Second, right and left trapezius tonus appeared similar while typing. Third, the best height that release the trapezius tonus the was as high as elbow and 3cm higher than elbow. Conclusion: With these above results, we suggest that the appropriate height of keyboard during typing to release the trapezius tonus most is the height of the elbow and 3cm higher than elbow. The study has important implications for focusing on the height of VDT worktable and complaining of a pain by oneself which are useful to establish a method of prevention of musculoskeletal disorder in work in the future.

• 한국건축시공학회지
• /
• 제15권6호
• /
• pp.653-660
• /
• 2015

Technologies for reducing construction duration are key factors in nuclear power plant construction projects, as a reduction in construction duration at the construction phase leads to a reduction in construction cost and an increase in profits through the early operation of the nuclear power plant. To analyze the constructability of the height of single-layer placement of formwork for the Reactor Containment Building (RCB) exterior wall through lateral pressure according to the height of concrete placement, the deformation criteria for formwork, and a new form design, 'MIDAS GEN (hereinafter referred to as MIDAS)' is used in this study. The cost and workload of formwork are derived according to the unit of height of the RCB exterior wall. Based on the result, it was found that the higher the RCB exterior wall, the higher the material cost, and the less the construction duration and the less the total number of formwork layers. Based on this result, it is believed that the material cost and the construction duration can be appropriately determined according to the formwork height.