Hyunsoo Lee

Dynamic Response Topology Optimization in the Time Domain using Equivalent Static Loads

Most topology optimization techniques find the optimal layout of a structure under static loads. Some studies are focused on dynamic response topology optimization because the dynamic forces act in the real world. Dynamic response topology optimization is solved in the time or frequency domain. A method for dynamic response topology optimization in the time domain is proposed using equivalent static loads. Equivalent static loads are static loads that generate the same displacement field as dynamic loads at each time step. The equivalent static loads are made by multiplying the linear stiffness matrix and the displacement field from dynamic analysis and used as multiple loading conditions for linear static topology optimization. The results of topology optimization are utilized in dynamic analysis again and a cyclic process is utilized until the convergence criterion is satisfied. The paradigm of the method was originally developed for size and shape optimizations. A new objective function is defined to minimize the peaks of the compliance in the time domain and a convergence criterion is newly defined considering that there are many design variables in topology optimization. The developed method is verified by solving some examples and the results are discussed.

Structural Optimization of a Joined Wing Using Equivalent Static Loads

The joined wing is a new concept of the airplane wing. The forewing and the aft wing are joined together in a joined wing. The range and loiter are longer than those of a conventional wing. The joined wing can lead to increased aerodynamic performance and reduction of the structural weight. In this research, dynamic response optimization of a joined wing is carried out by using equivalent static loads. Equivalent static loads are made to generate the same displacement field as that from dynamic loads at each time step of dynamic analysis. The gust loads are considered as critical loading conditions and they dynamically act on the structure of the aircraft. It is difficult to identify the exact gust-load profile; therefore, the dynamic loads are assumed to be a one-cosine function. Static response optimization is performed for the two cases: one uses the same design variable definition as dynamic response optimization, and the other uses the thicknesses of all elements as design variables; the results are then compared.

A Demonstration of BIM-Enabled Quantitative Circulation Analysis Using BERA Language

This paper describes a BIM-enabled spatial analysis approach that enables us to compute specific quantitative data using BERA (Building Environment Rule and Analysis) Language and its tool. By comparing design alternatives for an actual building model, this paper also demonstrates building circulation and its associated properties of numeric data. The conventional software-driven approaches have intrinsic limitations that include limited interfaces, restricted parameters, closed rules except pre-defined rules, etc. A script language-based approach, however, is strongly necessary for various and flexible design review tasks especially for retrieving and computing specific dataset. This paper specifically demonstrates actual design review tasks as follows: 1) comparison and visualization of the differences between design alternatives in terms of their different spatial allocations; 2) analyzing numeric data result, NDBC (Numeric Data of Building Circulation), for evaluation of building circulation factors in each department of building; and as a result, 3) overall quantitative analysis and its result will be reported on given actual BIM models in order to support design decision making among various spatial allocation scenarios. For the actual demonstration presented in this paper, we modified some part of BERA language applications and defined appropriate BERA program code and Java code that are executable on given BIM models.

BIM-enabled Definition of a Path Object and its Properties to Evaluate Building Circulation using Numerical Data

In this paper, we seek to define the path object and its properties as an instance level of a circulation path between two spaces. We further suggest the practical application of path objects in design review issues using numeric data on building circulation (NDBC) as a complete collection of circulation paths from a given Building Information Modeling (BIM) model. As the use of BIM is increasingly being implemented in architecture, engineering, and construction industries, rich data related to building objects and useful digital representations have been developed for specific circulation review tasks. Among the several benefits observed from such applications, this paper focuses on the BIM-enabled formal definition of the path object and its properties. We further demonstrate the use of several analysis applications using the NDBC. Due to the rich spatial information defined in a BIM model, path objects can be instantiated dynamically, and a specific data model for building circulation paths can be defined with a series of numeric data sets. In this paper, the formal definition of a path object and its properties are explored, and one of its NDBC applications is clarified and demonstrated for further circulation analysis tasks using a software tool developed by us.

Rule Checking Method-Centered Approach to Represent Building Permit Requirements

This paper aims to describe rule checking method, classification and its demonstration. As applications of BIM extends, there have been some challenging projects on automated building compliance checking. The current rule-making method is developercentered and thus is difficult to define rules without propound programming knowledge. This paper introduces high level rule making methods with law sentence-centered approach. The proposed methods have intuitive naming convention and are directly mapped with the predicate of the law sentences. Therefore, it is easy to infer function of the methods. According to the type of object and property in instance level, three hierarchies of method classification were set: 1) level 1 divides types of instance, 2) level 2 classifies the type of property, and 3) level 3 specifies the content of checking. From the level 3, representative rule checking method is defined. The representative method is subdivided into extended methods according to the specific object and property to check. The rule checking methods are combined together to form an intermediate pseudocode. The pseudo-code is later to be parsed into computer executable form. This paper mainly focuses on 1) introducing law sentence -centered rule checking method, 2) object and property-based classification of rule checking method, 3) method extensibility and 4) demonstration of rule checking methods with actual requirement sentences from the Korea Building Permit. The high level rule checking method is developed as a part of KBimLogic. KBimLogic is a software that translates the Korea Building Permit requirement into computer executable format. KBimLogic is now under development with government funding.

Visualization of the Airborne Dust Concentration on the Building Floor Plans

Indoor airborne dust concentration is one of the most adverse factors for human health. Especially, inhalable fine particles under 2.5micrometres in diameter (PM2.5) easily permeate into human body causing serious respiratory diseases. The problem is that the air pollutions are hard to be detected with human sense organs alone. Therefore, the development of an effective method to figure out the indoor air quality should be combined with other political approach. Moreover, measuring wide range of indoor environment continuously became affordable because of diverse sensors become downsized and low-priced. In this regards, as the way to collect and intuitively visualize the indoor dust concentration data, this paper proposes an integrated approach to the visualization of indoor dust concentration on the building floor plans. The entire system consists of four major stages: 1) Dust concentration measurement, 2) Data processing, 3) Layer generation and 4) Data mapping. The sensor toolkit was implemented with Arduino Uno Board and Optical dust sensor (GP2Y1010AU0F), which is able to measure fine particles over 0.8um at maximum. In short, this paper proposes a way to visualize of indoor dust density.

A Prediction of the Anticorrosion Life in a Steel Applying Zn–Al Thermal Metal Spraying Method Using an Electrochemical Experiment

This study performs an electrochemical experiment to quantitatively evaluate the corrosion resistance performance in a Zn–Al thermal metal spraying method and produces corrosion current density according to the type of corrosion resistance methods. Then, this study quantitatively estimates the durability life in the Zn–Al thermal metal spraying method based on this calculation. In the results of the calculation, the corrosion membrane produced in a Zn–Al thermal metal spraying method showed voltage differences more than 300 mV and that demonstrated enough corrosion performance with the corrosion resistance reaction of base materials and proper Zn–Al ratio, such as 50:50. Also, the results exhibited that the corrosion speed in a Zn–Al thermal metal spraying method was 0.66 time faster than that of the zinc galvanizing method in the estimation based on the standard of corrosion resistance service years in a zinc galvanizing method (JIS H 8641).

Structural Optimization of a Joined-Wing Using Equivalent Static Loads

The joined-wing is a new concept of the airplane wing. The fore-wing and the aft-wing are joined together in a joined-wing. The range and loiter are longer than those of a conventional wing. The joined-wing can lead to increased aerodynamic performance and reduction of the structural weight. In this research, dynamic response optimization of a joined-wing is carried out by using equivalent static loads. Equivalent static loads are made to generate the same displacement field as the one from dynamic loads at each time step of dynamic analysis. The gust loads are considered as critical loading conditions and they dynamically act on the structure of the aircraft. It is difficult to identify the exact gust load profile. Therefore, the dynamic loads are assumed to be (1-cosine) function. Static response optimization is performed for the two cases. One uses the same design variable definition as dynamic response optimization. The other uses the thicknesses of all elements as design variables. The results are compared.

Prevalence of and factors related to latent tuberculous infection among all employees in a referral hospital

SETTING Referral hospital, South Korea. OBJECTIVE To investigate the prevalence of and factors related to latent tuberculous infection (LTBI) among all hospital employees. DESIGN A cross-sectional study of 479 health care workers (HCWs) undergoing LTBI screening. RESULTS Overall prevalence of LTBI was 15.7%, 43.1% of whom initiated and completed LTBI treatment. Compared with HCWs without LTBI, those with LTBI were more likely to be older (P < 0.001), male (P = 0.003), work in low-risk departments (P = 0.013) and have more years of employment (P < 0.001). LTBI prevalence was highest in physicians (27.8%), followed by HCWs without patient contact (23.4%), nurses (8.3%) and other HCWs in contact with patients (6.9%). In multivariate analysis, compared with HCWs aged <20 years, those aged 40 years were 4.08 times more likely to have LTBI (P = 0.007). In addition, compared with HCWs working for <1 year, those working for 1-5 years or for 5 years were respectively 7.55 (P = 0.014) and 13.69 (P = 0.001) times more likely to have LTBI. CONCLUSIONS Our results suggest that modified LTBI screening strategies, including HCWs with no patient contact and encouraging LTBI treatment participation, might be helpful in improving LTBI control in HCWs.

An Approach to Translate Korea Building Act into Computer-Readable Form for Automated Design Assessment

This paper aims to describe an approach of implementation for an interpreter that translates the human natural language into a computer-readable form. Selected building permit-related sentences in Korea Building Act are within the scope of this paper. Among the various applications of BIM, the benefit of automated design assessment has been reported by some leading BIM challengers. The related regulations are usually defined in design guidelines, RFPs, Building Code, etc. The regulations are written in human-readable languages, and sometimes their implicit definitions hinder translating into the explicitly defined computer-readable forms. This paper focuses on the development of a translation process of converting Korea Building Act sentences into specific computer-readable forms such as a midlevel pseudo code and BERA (Building Environment Rule and Analysis) language. The scope of the research process and the overview of the approach to the translation from natural language sentences as follows; 1) Classification of the building objects and related properties from Korea Building Act sentences, 2) Classification of methods from predicate in sentences, 3) Parsing natural language sentence within logic rule-based process. In an actual implementation stage, this translation will be demonstrated by an actual GUI-based application.