• 한국건설관리학회논문집
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• 제22권2호
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• pp.21-30
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• 2021

기존 건설업은 타 산업 분야에 비해 생산성이 낮은 산업에 분류된다. 건설업의 생산성 저하를 해결하고자 전 세계적으로 기존 건설 방식보다 약 40% 생산성이 높은 오프사이트 건설(Off-Site Construction; OSC)에 집중하고 있다. 이러한 높은 생산성이 가능한 이유는 공장에서의 부재를 생산, 현장으로의 운반, 현장 조립 3단계를 연속적인 흐름으로 일관되게 유지하기 때문에 가능하다. 본 연구는 문헌고찰, 1차 사전 현장답사, 2차 온라인 설문, 3차 전문가 심층인터뷰를 통해서 기능조사를 수행하였다. 조사된 기능의 항목들을 편의성, 유연성, 관리 용이성, 의사소통, 안전성 5가지로 분류하였으며, 해당 기능특성에서는 유연성, 관리 용이성, 의사소통이 높은 점수를 나타내었다. 이는 건설현장의 공사 진행에 따른 변화, 공장의 생산일정, 운반 소요시간과 같은 다양성으로 인해 유연성, 관리 용이성, 의사소통이 중요한 기능특성으로 반환된 것으로 판단된다. 마지막으로 설문 조사된 기능 점수 결과에서 평균 점수 4점 이상에 해당된 기능 15개를 바탕으로 Functional Block Diagram을 구성하였다. 본 연구를 통해 OSC 운반 시스템이 구축된다면 성공적인 건설 OSC 프로젝트에 기여하고, 생산성을 높일 수 있을 것으로 판단된다.

• 설비공학논문집
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• 제14권12호
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• pp.1102-1139
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• 2002

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2000 and 2001 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD technologies were widely applied for developing facilities and their systems. (2) Most of papers related with heat transfer analysis and heat exchanger shows dealt with convection, evaporation, and channel flow for the design application of heat exchanger. The numerical heat transfer simulation studies have been peformed and reported to show heat transfer characteristics. Experimental as well as numerical studies on heat exchanger were reported, while not many papers are available for the system analysis including heat exchanger. (3) A review of the recent studies on heat pump system shows that performance analysis and control of heat pump have been peformed by various simulations and experiments. The research papers on multi-type heat pump system increased significantly. The studies on heat pipe have been examined experimently for change of working characteristics and strut lure. Research on the phase change has been carried out steadily and operation strategies of encapsulated ice storage tank are reported experimentally in several papers. (4) A review of recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. Evaporation and condensation heat transfer characteristics are investigated for tube shapes and new alternative refrigerants. Studies on components of refrigeration/air conditioning system are carried to examine efficiency for various compressors and performance of new expansion devices. In addition to thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out, however research works on two-phase flow seemed to be insufficient. (5) A review of the recent studies on absorption cooling system indicates that heat and mass transfer phenomena have been investigated to improve absorber performance. Various experimental data have been presented and several simulation models have been proposed. A review of the recent studies on duct and ventilation shows that ventilation indices have been proposed to quantify the ventilation performance in buildings and tunnels. Main efforts have been focused on the applications of ventilation effectiveness in practice, either numerically using computational fluid dynamics or experimentally using tracer gas techniques. (6) Based on a review of recent studies on indoor thermal environment and building service systems, research issues have mainly focused on many innovative ideas such as underfloor air-conditioning system, personal environmental modules, radiant floor cooling and etc. Also, the new approaches for minimizing energy consumption as well as improving indoor environmental conditions through predictive control of HVAC systems, various activities of building energy management and cost-benefit analysis for economic evaluation were highlighted.

• 한국정보처리학회논문지
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• 제2권4호
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• pp.499-508
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• 1995

도메인 분석은 새로운 응용시 손쉽게 재사용할 수 있도록 유사 시스템의 공통점 을 식별하는 활동이다. 대부분의 도메인 분석의 결과는 통일된 방식이 없이 도식적으 로 표현되고 수작업으로 재사용되고 있어서 분석명세의 재사용성이 작다. 도메인 분석 정보도 수작업 대신에 잘 정의된 구문을 갖는 도메인 분석명세 언어로 표현하여 명세 의 적절성 검사와 재사용의 연산을 통해 도메인 분석명세 재사용의 자동화가 가능하다. 본 연구에서는 도메인 분석의 결과를 도메인 분석명세 언어로 표현하여 재사용할 수 있도록 도메인 부석명세 재사용 처리기를 설계 구현하고 대여 도메인에 적용하여 새로 운 명세의 인스탄스를 얻을 수 있었다. 아울러 종전의 데이타 흐름도 지원 도구를 통 합 재사용 방식과 분석정보 처리기를 통한 재사용 시간을 비교하였으며 두 가지 방식 은 서로의 단점을 보완하여 재사용성을 향상시킬 수 있음을 발견하였다.

• 한국산업보건학회지
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• 제24권4호
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• pp.484-491
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• 2014

Objectives: An image processing program for asbestos fibers analyzing the gradient components and partial linearity was developed in order to accurately segment fibers. The objectives were to increase the accuracy of counting through the formulation of the size and shape of fibers and to guarantee robust fiber detection in noisy backgrounds. Methods: We utilized samples mixed with sand and sepiolite, which has a similar structure to asbestos. Sample concentrations of 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, and 3%(w/w) were prepared. The sand used was homogenized after being sieved to less than $180{\mu}m$. Airborne samples were collected on MCE filters by utilizing a personal pump with 2 L/min flow rate for 30 minutes. We used the NIOSH 7400 method for pre-treating and counting the fibers on the filters. The results of the NIOSH 7400 method were compared with those of the image processing program. Results: The performance of the developed algorithm, when compared with the target images acquired by PCM, showed that the detection rate was on average 88.67%. The main causes of non-detection were missing fibers with a low degree of contrast and overlapping of faint and thin fibers. Also, some duplicate countings occurred for fibers with breaks in the middle due to overlapping particles. Conclusions: An image detection algorithm that could increase the accuracy of fiber counting was developed by considering the direction of the edge to extract images of fibers. It showed comparable results to PCM analysis and could be used to count fibers through real-time tracking by modeling a branch point to graph. This algorithm can be utilized to measure the concentrations of asbestos in real-time if a suitable optical design is developed.

• 대한인간공학회지
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• 제36권5호
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• pp.437-446
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• 2017

Objective: This study aims to draw an efficient UI design by comparing the usability of App drawer and single-layered home screens, which are smartphone home screens. Background: Because smartphone home screen is frequently used including the installation, deletion, and editing of APPs, it should be designed with easily controllable information structure. There is a need to seek a user-friendly UI by comparing the usability of App drawer and single-layered home screens, of which methods to search Apps are different. There is also a need to examine an efficient UI and the factors to improve from the user perspective. Method: This study targeted 30 Android OS and iOS users to evaluate the App drawer and single-layered home screens, of which UI structures are different. Each participant was instructed to carry out an App searching task and App deleting task, and the execution time and the number of errors were measured. After the tasks were completed, they evaluated satisfaction through a questionnaire survey. Results: In the App searching task with low task level, there was no difference in execution level between the App drawer and single-layered home screens. However, the single-layered home screen showed higher efficiency and accuracy in the App deleting task with high task level. As for the group difference according to use experience, there was no difference in satisfaction among Android OS users, but iOS user satisfaction with single-layered home screen with which they were familiar was higher. Conclusion: As for home screen usability, the single-layered home screen UI structure can be advantageous, as task level is higher. Repulsion was higher, when users, who had used easier UI, used complex UI in comparison with user satisfaction, when users familiar with complex UI used easier UI. A UI indicating the current status with clear label marking through a task flow chart-based analysis, and a UI in which a user can immediately recognize by exposing hidden functions to the first depth were revealed as things to improve. Application: The results of this study are expected to be used as reference data in designing smartphone home screens. Especially, when iOS users use Android OS, the results are presumed to contribute to the reduction of predicted barriers.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.73-82
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• 2012

The main and side reactions of the three selective catalytic reduction (SCR) reactions with ammonia over a vanadium-based catalyst have been investigated using synthetic gas mixtures in the temperature range of $170{\sim}590^{\circ}C$. The three SCR reactions are standard SCR with pure NO, fast SCR with an equimolar mixture of NO and $NO_2$, and $NO_2$ SCR with pure $NO_2$. Vanadium based catalyst has no significant activity in NO oxidation to $NO_2$, while it has high activity for $NO_2$ decomposition at high temperatures. The selective catalytic oxidation of ammonia and the formation of nitrous oxide compete with the SCR reactions at the high temperatures. Water strongly inhibits the selective catalytic oxidation of ammonia and the formation of nitrous oxide, thus increasing the selectivity of the SCR reactions. However, the presence of water inhibits the SCR activity, most pronounced at low temperatures. In this study, the experimental results are analyzed by means of a dynamic one-dimensional isothermal heterogeneous plug-flow reactor (PFR) model according to the Eley-Rideal mechanism.

• 한국대기환경학회지
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• 제23권1호
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• pp.14-28
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• 2007

This study presented the selection of ozone ($O_3$) potential factors and designed and assessed its potential prediction model using multiple-linear regression equations in Ulsan area during the springtime from April to June, $2000{\sim}2004$. $O_3$ potential factors were selected by analyzing the relationship between meterological parameters and surface $O_3$ concentrations. In addition, cluster analysis (e.g., average linkage and K-means clustering techniques) was performed to identify three major synoptic patterns (e.g., $P1{\sim}P3$) for an $O_3$ potential prediction model. P1 is characterized by a presence of a low-pressure system over northeastern Korea, the Ulsan was influenced by the northwesterly synoptic flow leading to a retarded sea breeze development. P2 is characterized by a weakening high-pressure system over Korea, and P3 is clearly associated with a migratory anticyclone. The stepwise linear regression was performed to develop models for prediction of the highest 1-h $O_3$ occurring in the Ulsan. The results of the models were rather satisfactory, and the high $O_3$ simulation accuracy for $P1{\sim}P3$ synoptic patterns was found to be 79, 85, and 95%, respectively ($2000{\sim}2004$). The $O_3$ potential prediction model for $P1{\sim}P3$ using the predicted meteorological data in 2005 showed good high $O_3$ prediction performance with 78, 75, and 70%, respectively. Therefore the regression models can be a useful tool for forecasting of local $O_3$ concentration.

• 한국물환경학회지
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• 제26권4호
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• pp.654-663
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• 2010

Attention has increasingly focused on the pollutant load discharged from rural area since the enforcement of total maximum daily loads (TMDLs) in korea. As one of the methods to control the inflow of pollutant load during wet weather events, local governments are attempting to apply non-point source control facility. To design those facilities appropriately, it is essential to understand the runoff characteristics of pollutants such as TSS, $BOD_5$, $COD_{Cr}$, TP and TN. In the paper, the quantitative analyses for pollutant runoff characteristics were examined in a small rural watershed with the area of about 53 hectares. For a dry weather day and wet weather events, variation patterns of dry weather flow and runoff characteristics of wet weather flows were monitored and investigated. The runoff model using XP-SWMM reflecting the landuse types of the watershed in detail was simulated to perform the sensitivity analyses for several factors influencing on their hydrograph and pollutographs. As a result, for the case of medium and small rainfall events (i. e. total rainfall of 35.8 and 17.5 mm), the impervious area including green house, roof and road which covers relatively low portion of total area (i. e. 16%) caused substantial first flush and the majority of total runoff load. Therefore, it has been concluded that the runoff characteristics of each pollutant and distribution of impervious area should be considered for the establishment of the control strategy of non-point pollutant runoff at a rural area.

• 정보처리학회논문지C
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• 제14C권3호
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• pp.267-276
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• 2007

라우팅 프로토콜의 하나인 OSPF는 라우터 수가 많고 불안정 링크 수가 많으면 재계산 수는 급격히 증가한다. 따라서 일반적으로 한 Area에서 라우터 수는 50개 보다 작게 보유해야 하며 링크가 불안정할 경우 더욱 Area는 작게 해야 한다. 군 전술 데이터 망은 유사시(전시) 사용하는 데이터 망으로 신속한 이동 설치를 위해 무선 전송로를 사용하며 이 때문에 전송속도가 낮고, 전송로가 불안정하다. 또한 전시 많은 라우터 고장과 링크 두절 및 회복 현상 발생될 것으로 예상된다. 그럼에도 불구하고 현재의 군 전술 데이터 망은 일반적인 네트워크 설계시 산정되는 라우터 수량보다 라우터 수가 1.5배 많다. 본 논문은 현재 군에서 큰 규모로 선정한 Area로 인한 재계산 수의 증가로 사용자 트래픽 흐름에 제한이 됨을 시뮬레이션을 통하여 밝혔다.

• Computers and Concrete
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• 제12권2호
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• pp.131-149
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• 2013

Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.