• Korean Journal of Construction Engineering and Management
• /
• v.12 no.6
• /
• pp.79-92
• /
• 2011

Quantity take-off is one of the critical tasks that determine the cost of a construction project, and its result should be accurate and reliable. BIM-based quantity take-off is a very attractive process for practitioners since the quantity take-off can be done automatically in a fast and accurate way. However, the result of BIM-based quantity take-off can be varied depending on how BIM was modeled. As a project progresses, more detailed design information is getting available, and it can be expected that the degree of completeness and accuracy for the BIMbased quantity take-off is going to be improved as well. However, when estimation is performed at each stage of a project life-cycle, there is no way to measure or forecast how accurate of the quantity take-off result from the BIM data given at the current stage. Therefore, this research derived factors that affect the BIM-based quantity takeoff and developed a methodology and framework to measure and forecast the completeness of BIM-based quantity take-off. The measurement framework and index that are proposed by this research was verified and validated for their consistency and feasibility through six pilot projects.

• Journal of Bio-Environment Control
• /
• v.18 no.2
• /
• pp.112-118
• /
• 2009

To determine the effects of circulation frequency of nutrient solution, three frequencies of 10min. on/10min. off; 10min. on/110min. off; and 10min. on/1,430min. off. treatments were applied to leafy vegetable production using deep flow technique (DFT) systems and their growth and phytonutrient content were investigated. In the 10min. on/I,430min. off treatment, dissolved oxygen concentration (DOC) 17 days after treatment decreased to 2.8mg. $L^{-1}$, known to be a low DOC that causes hypoxia, and thereafter decreased to 1.5mg. $L^{-1}$ 20 days after treatment. Fresh weight of 7 leafy vegetables in the 10min. on/1,430min. off treatment was lower by 0${\sim}$24% than those in the 10min. on/110min. off treatment, and those in the 10min. on/10min. off was higher by -2${\sim}$34% than those in the 10min. on/110min. off treatment as control. As the more frequent circulation was applied, the higher phosphorous content and the lower carbon to nitrogen ratio (C/N ratio) and total ascorbic acid contents were resulted. Results indicate that the circulation frequency of 110min, on/110min. off could be recommended for the production of the tested leafy vegetables in DFT systems.

• Journal of Electrochemical Science and Technology
• /
• v.11 no.2
• /
• pp.172-179
• /
• 2020

The impact of effective parameters on the electrodeposition rate optimization of Au-Cu alloy at high thicknesses on the silver substrate was investigated in the present study. After ensuring the formation of gold alloy deposits with the desired and standard percentage of gold with the cartage of 18K and other standard karats that should be observed in the manufacturing of the gold and jewelry artifacts, comparing the rate of gold-copper deposition by direct and pulsed current was done. The rate of deposition with pulse current was significantly higher than direct current. In this process, the duty cycle parameter was effectively optimized by the "one factor at a time" method to achieve maximum deposition rate. Particular parameters in this work were direct and pulse current densities, bath temperature, concentration of gold and cyanide ions in electrolyte, pH, agitation and wetting agent additive. Scanning electron microscopy (SEM) and surface chemical analysis system (EDS) were used to study the effect of deposition on the cross-sections of the formed layers. The results revealed that the Au-Cu alloy layer formed with concentrations of 6gr·L^-1 Au, 55gr·L^-1 Cu, 24 gr·L^-1 KCN and 1 ml·L^-1 Lauryl dimethyl amine oxide (LDAO) in the 0.6 mA·cm^-2 average current density and 30% duty cycle, had 0.841 ㎛·min^-1 Which was the highest deposition rate. The use of electrodeposition of pure and alloy gold thick layers as a production method can reduce the use of gold metal in the production of hallow gold artifacts, create sophisticated and unique models, and diversify production by maintaining standard karats, hardness, thickness and mechanical strength. This will not only make the process economical, it will also provide significant added value to the gold artifacts. By pulsating of currents and increasing the duty cycle means reducing the pulse off-time, and if the pulse off-time becomes too short, the electric double layer would not have sufficient growth time, and its thickness decreases. These results show the effect of pulsed current on increasing the electrodeposition rate of Au-Cu alloy confirming the previous studies on the effect of pulsed current on increasing the deposition rate of Au-Cu alloy.

• The Korean Journal of Emergency Medical Services
• /
• v.14 no.3
• /
• pp.71-81
• /
• 2010

Purpose: To minimize an interruption in chest compression, reduce the hands-off time, the American Heart Association has recommended the ratio of chest compression to ventilation ratio to 30:2 from 2005 CPR guideline to 2010 CPR guideline. However, current studies have shown that the hands-off time was > 10 seconds with that method. For this reason, we devised new CPR method that a ventilation to chest compression ratio of 2:30 to reduce pt assessment time and skipped the assessment step of carotid artery pulse would be a more effective way to reduce the hands-off time & the time to set the CPR. According to the more detailed purpose are listed below. 1) We would like to confirm efficiency of a ventilation to chest compression ratio of 2:30 than a chest compression to ventilation ratio of 30:2 to reduce the hands-off time & the time to set the CPR. 2) We would like to evaluate possibility of increasing for chest compression accuracy of a ventilation to chest compression ratio of 2:30 than a chest compression to ventilation ratio of 30:2 3) We would like to evaluate possibility of increasing for ventilation accuracy of a ventilation to chest compression ratio of 2:30 than a chest compression to ventilation ratio of 30:2 Methods: According to 2005 American Heart Association Guidelines, 60 paramedic students(20 students X freshmen, sophomore, junior) performed 5 cycles of 3~ chest compressions : 2 ventilations after A, B, C evaluation with Laerdal Resusci R Anne SkillReporters. After 5 minutes rest, the 60 students performed 5 cycles of 2 ventilations : 30 chest compressions after A, B evaluation with the manikins between 13 and 17 September 2010. The short reports including speed & accuracy of chest compression, respiratory, CPR cycle were gained from the manikins. Hands-off times were measured by assistants. Results: Recently, the importance of high quality CPR was emphasized in order to perform the CPR faster and more accurate. To find out improving the conventional CPR method, we switch the procedure of the compression and the ventilation. By switching the procedure back and forth, we are able to compare the effectiveness of CPR between two type of CPR method which are 2:30 and 30:2 methods. 2:30 is that the breaths is delivered twice, first and perform 30 compressions while 30:2 perform 30 compressions first and give 2 breaths followed by the ABC method. Also, we verify the effectiveness of the hands off time, compression accuracy of the compression through the comparison of the two procedure as mentioned earlier. Consequently research verified that 2:30 is the efficient by providing faster set up delivering more accurate chest compression. Conclusion: 2:30 can minimize a time delay from cardiac standstill until starting the chest compression. In addition, hands-off time which is an interruption in chest compression can be shortened by 2:30 method, which result to effective oxygenation of coronary artery & maintenance of the bloodstream. Once again, performing the 2:30 method provide lessen hands off time and increase the accuracy of the chest compression.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.13 no.5
• /
• pp.57-63
• /
• 2009

A modeling and simulation program for an environmental control system (ECS) of a pod installed under wings of an aircraft was developed in order to estimate the system‘s performance during a flight. First, through the system configuration analysis in the main operational condition of the aircraft system, an ECS configuration adopting an air cycle machine (ACM) was selected. Therefore the modeling program was developed to simulate the ECS with an ACM. Second, the sensitivity analyses on performance variation of main components were conducted to complete the conceptual design of the ECS. A design point for the system and its components was obtained through the analysis with the modeling and simulation program. The design point for the system and components was obtained through the analysis with the modeling and simulation program. Third, in order to study the feasibility of the ECS configuration, off-design performances of the ECS on various flight conditions, such as take off, maneuver, cruise and landing etc were estimated. Dynamic characteristics were analyzed by transient performance evaluations.

• Clinical and Experimental Reproductive Medicine
• /
• v.41 no.2
• /
• pp.75-79
• /
• 2014

Objective: To study the effect of body composition on reproduction in women with unexplained infertility treated with a controlled ovarian hyperstimulation and intrauterine insemination programme. Methods: This prospective observational study was conducted on 308 unexplained infertile women who were scheduled for a controlled ovarian hyperstimulation and intrauterine insemination programme and were grouped as pregnant and non-pregnant. Anthropometric measurements were performed using TANITA-420MA before the treatment cycle. Body composition was determined using a bioelectrical impedance analysis system. Results: Body fat mass was significantly lower in pregnant women than in non-pregnant women ($15.61{\pm}3.65$ vs. $18.78{\pm}5.97$, respectively) (p=0.01). In a multiple regression analysis, body fat mass proved to have a stronger association with fecundity than the percentage of body fat, body mass index, or the waist/hip ratio (standardized regression coefficient${\geq}0.277$, t-value ${\geq}2.537$; p<0.05). The cut-off value of fat mass, which was evaluated using the receiver operating characteristics curve, was 16.65 with a sensitivity of 61.8% and a specificity of 70.2%. Below this cut-off value, the odds of the pregnancy occurrence was found to be 2.5 times more likely. Conclusion: Body fat mass can be predictive for pregnancy in patients with unexplained infertility scheduled for a controlled ovarian hyperstimulation and intrauterine insemination programme.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2008.11a
• /
• pp.18-18
• /
• 2008

3차원 패키징 System In Package (SIP)구조에서 Chip to Chip 단위 Interconnection 역할을 하는 Through Silicon Via(TSV)를 형성하기 위하여 Pulsating RF bias가 장착된 Inductively Coupled Plasma Etcher 장비를 이용하였다. 이 Pulsating 플라즈마 공정 방법은 주기적인 펄스($50{\sim}500Hz$)와 듀티($20{\sim}99%$) cycle 조절이 가능하며, 플라즈마 에칭특성에 영향을 주는 플라즈마즈마 발생 On/Off타임을 조절할 수 있다. 예를 들면, 플라즈마 발생 Off일 경우에는 이온(SFx+, O+)과 래디컬(SF*, F*, O*)의 농도 및 활성도를 급격하게 줄이는 효과를 얻을 수가 있는데, 이러한 효과는 식각 에칭시, 이온폭격의 손상을 급격하게 줄일 수 있으며, 실리콘 표면과 래디컬의 화학적 반응을 조절하여 에칭 측벽 식각 보호막 (SiOxFy : Silicon- Oxy- Fluoride)을 형성하는데 영향을 미친다. 그리고, TSV 형성에 있어서 큰 문제점으로 지적되고 있는 언더컷과 수평에칭 (Horizontal etching)을 개선하기 위한 방법으로, Black-Siphenomenon을 이번 실험에 적용하였다. 이 Black-Si phenomenon은 Bare Si샘플을 이용하여, 언더컷(Undercut) 및 수평 에칭 (Horizontal etching)이 최소화 되는 공정 조건을 간편하게 평가 할 수 있는 방법으로써, 에칭 조건 및 비율을 최적화하는 데 효율적이었다. 결과적으로, Pulsating RF bias가 장착된 Inductively Coupled Plasma Etcher 장비를 이용한 에칭실험은 펄스 주파수($50{\sim}500Hz$)와 듀티($20{\sim}99%$) cycle 조절이 가능하여, 이온(SFx+, O+)과 래디컬(SF*, F*, O*)의 농도와 활성화를 조절 하는데 효과적이었으며, Through Silicon Via (TSV)를 형성 하는데 있어서 Black-Si phenomenon 적용은 기존의 Continuous 플라즈마 식각 결과보다 향상된 에칭 조건 및 에칭 프로파일 결과를 얻는데 효과적이었다.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.12
• /
• pp.1-15
• /
• 2020

In this paper, we propose a novel method for converting the existing 2D processes in the design and construction phase of civil engineering, to the future BIM-based processes. First, we compare and analyze the actual application processes of the outputs of the existing 2D method and the outputs of the 3D BIM method, for the whole process of BIM design of earthworks and road structures and integrated utilization of quantity, process(4D) and construction cost(5D), in view of life-cycle. The proposed method acquire the outputs of the design phase integrating IFC international common standard file information and CBS/OBS/WBS standard classification scheme information, and acquire the outputs of the construction stage by using an integrated utilization module for quantity, process(4D) and construction cost(5D). Ultimately, we intend to commercialize the step by step technologies for BIM design and construction in civil engineering by using the proposed method.

• Plant Journal
• /
• v.17 no.4
• /
• pp.35-40
• /
• 2021

In this study, a technical characteristic test was conducted on the gas turbine generator system of Seoincheon Combined cycle no.6 to derive and verify the model constants. As a result of the generator maximum/minimum reactive power limit test, the maximum reactive power limit is 80 MVar and the minimum is -30 MVar. The generator uses the GENROU model, the field time constant (T'do) is 4.077 s, and the inertial constant (H) is 5.461 P.U. Excitation system used ESST4B model to derive and verify model constants by simulating no-load 2% AVR step test, PSS modeling derived from PSS2A model constants, and simulated and compared measurement data measured when PSS off/on Did. The GGOV1 model was used for the governor-turbine, and the numerical stability of the determined governor-turbine model constant was verified by simulating a 10% governor step test through the PSS/E simulation program

• Journal of Environmental Health Sciences
• /
• v.48 no.4
• /
• pp.216-226
• /
• 2022

Background: The amount of smoking in adolescence increases with a younger age of smoking initiation and affects physical health. To establish and evaluate smoking-related policies, it is important to determine actual smoking status. Validation of self-reported questionnaires can identify the accuracy of the questionnaire data reflecting smoking status. Objectives: The purpose of this study was to evaluate the validity of self-reported smoking status and identify factors affecting the accuracy of self-reported smoking in South Korean adolescents. Methods: This study investigated the consistency between cotinine concentrations and self-reported questionnaire data through the analysis of urine samples collected from 922 adolescents aged 13~18 among the participants of Cycle 3 of the Korean National Environmental Health Survey. Smoking status was classified using the cotinine cut-off point of 39.85 ㎍/L in adolescents, and factors affecting the accuracy were analyzed through multiple logistic regression analysis. Results: The smoking rates according to the self-reported questionnaire and cut-off point-based cotinine concentrations among adolescents were 3.1% and 5.1%, respectively. The results found 97.1% consistency between self-reported smokers and smokers according to cotinine concentration. Factors affecting the discrepancy showed a significant relationship, including gender, secondhand smoke, and use of e-cigarettes. Conclusions: The results can be used as basic data to establish a smoking policy for adolescents through continuous monitoring and improvement of questionnaire items of factors affecting the discrepancy.