Joon-Young Park

Task-oriented design of robot kinematics using the Grid Method

This paper presents a task-oriented design method for robot kinematics based on the Grid Method, which is widely used in the finite difference method and heat transfer/fluid flow analyses. This approach drastically reduces the complexity of the whole problem and increases the efficiency compared with previous approaches. More specifically, the Grid Method with a new formulation simplifies the design to a problem of a four-design-variable unit grid, which does not require solving inverse/forward kinematics. The efficiency of the Grid Method has been confirmed through a kinematics design of a planar robot for nuclear power plants and spatial robots.

Battles with false positives in static analysis of JavaScript web applications in the wild

Now that HTML5 technologies are everywhere from web services to various platforms, assuring quality of web applications becomes very important.While web application developers use syntactic checkers and type-related bug detectors, extremely dynamic features and diverse execution environments of web applications make it particularly difficult to statically analyze them leading to too many false positives.Recently, researchers have developed static analyzers for JavaScript web applications addressing quirky JavaScript language semantics and browser environments, but they lack empirical studies on the practicality of such analyzers.In this paper, we collect 30 JavaScript web applications in the wild, analyze them using SAFE, the state-of-the-art JavaScript static analyzer with bug detection, and investigate false positives in the analysis results.After manually inspecting them, we classify 7 reasons that cause the false positives: W3C APIs, browser-specific APIs, JavaScript library APIs, dynamic file loading, dynamic code generation, asynchronous calls, and others.Among them, we identify 4 cases which are the sources of false positives that we can practically reduce.Rather than striving for sound analysis with unrealistic assumptions, we choose to be intentionally unsound to analyze web applications in the real world with less false positives.Our evaluation shows that the approach effectively reduces false positives in statically analyzing web applications in the wild.

Commandless input shaping technique

Although IST possesses the capability to effectively suppress residual vibrations, it lacks the ability to suppress vibrations caused by external disturbances. In the following paper, we have proposed the method of Commandless IST (CIST) to overcome this weak point. According to CIST, when a vibration is detected, the impulse is generated by a control input which in turn triggers a reverse vibration to negate the original vibration, resulting in the complete elimination of the original vibration. The general idea and design methods of CIST are provided and the effectiveness of CIST is confirmed through computer simulations. Also, according to experiments conducted to suppress vibrations arising when unloading the hydraulic telescopic handler, it was found that by applying CIST, the level of vibrations was reduced by over 75%.

Analysis of Differences in Geomorphological Characteristics on Initiation of Landslides and Debris Flows

Recently, damages caused by landslides have increased due to increasing frequency of localized heavy rains. In order to prevent land-slide disasters efficiently, more studies related to predicting the initiation areas of debris flows causing large scale damages are nec-essary. In Korea, most debris flows mobilize from landslides. The studies on the mobilization of debris flows can be classified intogeotechnical based approach, geomorphological approach using local topographic properties and analytical approach based on hydro-logical properties. Geomorphological approach has merits including the convenience of obtaining topographical data and the appli-cability toward a large area. In this study, ten GIS based geomorphological data were obtained from landslides and debris flowsinitiation areas located in Seoul, Gyeonggi and Gangwon Provinces. A relationship analysis was conducted among the topographicparameters to study geomorphological characteristics discerning landslides and debris flows. A threshold, which can be used for theprediction of debris flow initiation areas, was proposed through the relationship analysis.Key words : Landslide, Debris flow, Mobilization, Geomorphological characteristics, Threshold

Interaction Restraint: Enforcing Adaptive Cognitive Tasks to Restrain Problematic User Interaction

We propose an interaction restraint that aims to degrade interactivity of a device, for example, by asking users to perform a mandatory cognitive task whenever they start an interaction. This mechanism is designed to help users to self-reflect upon their interaction intent with the devices, and thus they can break the habit of unconscious frequent access to their smartphones. We perform a preliminary study to understand the design requirements of the cognitive tasks and develop a high-fidelity prototype. Our field trial clearly documents that a positive influence of interaction restraints on deterring habitual frequent use of smartphones.

EventHandler-Based Analysis Framework for Web Apps Using Dynamically Collected States

JavaScript web applications (apps) are prevalent these days, and quality assurance of web apps gets even more important. Even though researchers have studied various analysis techniques and software industries have developed code analyzers for their own code repositories, statically analyzing web apps in a sound and scalable manner is challenging. On top of dynamic features of JavaScript, abundant execution flows triggered by user events make a sound static analysis difficult.

Towards Analysis and Bug Finding of JavaScript Web Applications in the Wild

We present our journey to analyze and find bugs in JavaScript web applications in the wild. We describe technical challenges in analyzing them and our solutions to address the challenges via a series of open source analysis frameworks, the scalable analysis framework for ECMAScript (SAFE) family.

A framework for dynamic inter-device task dispatch with eventual consistency

The Internet of Things (IoT) allows various things like mobile devices and electronic appliances to communicate over network. Inter-device apps can share data between devices and dispatch specific tasks to other devices to utilize their resources. The prevalence of JavaScript web apps that can run anywhere providing any browsers opens the gate to unanticipated interactions between devices. However, the current techniques require developers construct tasks to dispatch statically with strong consistency, and they do not provide any disciplined way to develop inter-device apps. In this paper, we propose IDTD (Inter-Device Task Dispatch), a framework that allows developers to construct and dispatch tasks into multiple devices dynamically with eventual consistency in a systematic manner. We provide a high-level architecture of IDTD, prove the soundness and eventual consistency of the framework, and present its practical usability.

Analysis of JavaScript web applications using SAFE 2.0

JavaScript has been the language for web applications, and the growing prevalence of web environments in various devices makes JavaScript web applications even more ubiquitous. However, because JavaScript and web environments are extremely dynamic, JavaScript web applications are often vulnerable to type-related errors and security attacks. To lessen the problem, researchers have developed various analysis techniques in different analyzers, but such analyzers are not especially aimed for ease of use by analysis developers. In this paper, we present SAFE 2.0, a scalable analysis framework for ECMAScript especially designed as a playground for advanced research in JavaScript web applications. SAFE 2.0 is light-weight, which supports pluggability, extensibility, and debuggability. Demo video: https://youtu.be/ZI_emiRMoxQ.

A case study on determining real-time landslide early warning level by sequentially applying ERI and infiltration-slope stability coupled model

A has a large variation in water resources and causes frequent occurrence of natural disasters such as flood and drought. Of course, there are various reasons for these disasters, but the current climate change increases the variability of temporal and spatial patterns for the disasters and causes the difficulties in water resources management over the region. The aim of this study is to anlalyze climate change impact on water resources in the Asia monsoon region based on AR5 scenario. The future changes in temperature, precipitation and runoff according to climate change are evaluated and the corresponding variability characteristics are analyzed in the study region. GCMs are used for simulating future climate chnage scenarios and bilinear method is applied to interpolate the scenarios at 0.5 degree horizontal grid scale. Delta method is used for bias correction. To assess the performance of GCMs output that reflect well the Asian monsoon region, Taylor diagram approach is adopted in this study. The observed precipitation and temperature data were obtained from APHRODITE, which is used for input of hydrologic VIC model. As results, annual average temperature was increased in general, while the precipitation and runoff were different patterns in specific sites In the past preiods, annual average temperature, precipitation and runoff were about 10.5°C, 672mm and 355mm, respectively. Future projections based on climate change scenario represent gradual rise in temperature in all regions, but demonstrate higher increase in temperature change with increasing latitudes. The spatial and temporal changes in precipitation and runoff are provided in this study. The flood and drought prone areas in Asia monsoon region due to climate change are analyzed and compared with the results from AR4.Brown troutta (sala trutta) is a European species of salmonid fish that has been extensively imported from suitable places around the world. It involves the rise of pure water, called the river ecotype. Brown trout is widely imported from suitable places around the world, including North and South America, Australia, Asia, and South East Africa. Climate change is one of the most important global processes in the Biosphere, and fish as part of Biology do not care about this process. Coldwater fish and, especially the Brown trout (sala trutta), are more sensitive to predictable changes in temperature levels and streams. The introduction of brown trout has established a livelihood, wildlife in many imported countries. Water temperature is a major problem in the ecological study of white water because it affects physical, chemical and facial processes and, therefore, the organisms that live at all or part of this in water. Therefore, climate change can preclude the availability of suitable habitat for many species of fish including trout brown. Weather simulations predict an increase in temperature and extreme events. These changes are expected to lead to a logical change in the hydrological cycle which has a significant impact on the ecological integrity of the aquatic environment. Brown trout will be very close to their body function limits and thus jeopardize the production of somatic and reproductive biomass. Some ability to adapt to high temperatures is possible but overheating of the body may be unavoidable. Genetic diversity and apparent variability in plasticity may compensate for the effects of climate change, but rapid changes may interfere with adaptability because cohesion is not limited to changes in temperature and signals of intrusion / sub-aquaculture will affect ecosystems. Within this context it appears to be a strategy to predict the effects of global change in aquatic biodiversity and the distribution of species in order to identify adequate measures aimed at mitigating the impact of climate change on ecosystems. For this purpose we have made a simulation based on a series of speculation models to predict the distribution of the brown stem in the highlands of the Phe River basin (North Italy). The 140-year hypothesis, based on the Local Climate model, is used to force the hydrological model to cycle the hydrological cycle. The results of hydrological simulations, particularly variations in temperature and humidity, are then used to confirm areas where target species are expected to occur. The results show how this proposed complex approach is able to reproduce, with good confidence, the current distribution of brown trout. The speculation of the coming years indicates a shift in distribution to the upper parts of the base, with a reasonable reduction in areas where trout brown can survive, produce and grow. This work also focuses on the potential use of the proposed method of assessing the effects of climate change on complex environmental systems