Kristián Košťál

Mr. Kristián Košťál

orcid

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 February 2019 in Sensors
Verified
Journal Article
Open access
PDF file
KKKristián Košťál
Kristián Košťál
PHPavol Helebrandt
Pavol Helebrandt
MBMatej Belluš
Matej Belluš
MRMichal Ries
Michal Ries
Ivan KotuliakIvan Kotuliak
Ivan Kotuliak
Nowadays, we are surrounded by a large number of IoT (Internet of Things) devices and sensors. These devices are designed to make life easier and more comfortable. Blockchain technology, especially its mass application, is becoming a term number one. Adoption of blockchain into enterprise networks still has a few challenges that need to be tackled. Utilizing blockchain can bring increased security and efficiency of network maintenance. The key feature of the blockchain, immutability, brings resistance to unauthorized modifications. The whole history of device configuration changes is stored in the blockchain, hence recovery after incidents is very straightforward. This paper extends our previous studies. We are introducing an improved architecture for management and monitoring of IoT devices using a private blockchain. The majority of the system is built on a chaincode, which handles CRUD (Create, Read, Update, Delete) operations as well as encryption and access control. Device configuration files are stored in the blockchain. When a modification occurs, the device downloads a new configuration in a simple manner. The chaincode receives notification whether setup was successful and this history is available for administrators. Our results show that such a system is possible and dissemination of configuration changes to IoT devices can be secured by the blockchain. The key novelty of our solution is a distributed management of configuration files of IoT devices in enterprise networks utilizing blockchain technology. This is essentially improving security and storage options for configurations in the blockchain.

1 September 2019
Verified
Conference Paper
Closed access
VVViktor Valastin
Viktor Valastin
KKKristián Košťál
Kristián Košťál
RBRastislav Bencel
Rastislav Bencel
IKIvan Kotuliak
Ivan Kotuliak

1 October 2019
Verified
Conference Paper
Closed access
KKKristián Košťál
Kristián Košťál
RBRastislav Bencel
Rastislav Bencel
MRMichal Ries
Michal Ries
IKIvan Kotuliak
Ivan Kotuliak
Some forms of voting have been here ever since. Mostly used form all over the world are paper ballots. Electronic voting schemes are being popular only in the last decade and they are still unsolved. E-voting schemes bring problems mainly regarding security, credibility, transparency, reliability, and functionality. Estonia is the pioneer in this field and may be considered the state of the art. But there are only a few solutions using blockchain. Blockchain can deliver an answer to all of the mentioned problems and furthermore bring some advantages such as immutability and decentralization. The main problems of technologies utilizing blockchain for e-voting are their focus on only one field or lack of testing and comparison. In this paper, we present a blockchain-based e-voting platform, which can be used for any kind of voting. It is fully utilized by blockchain and all processes can be handled within it. After the start of the voting, the platform behaves as fully independent and decentralized without possibilities to affect the voting process. The data are fully transparent, but the identity of voters is secured by homomorphic encryption. We have tested and compared our solution in three different blockchains. The results show, that both public and private blockchains can be used with only a little difference in the speed. The key novelty of our solution is a fully decentralized management of e-voting platform through blockchain, transparency of the whole process and at the same time security and privacy of the voters thanks to homomorphic encryption.

1 September 2018
Verified
Conference Paper
Closed access
KKKristián Košťál
Kristián Košťál
TKTomáš Krupa
Tomáš Krupa
MGMartin Gembec
Martin Gembec
IVIgor Vereš
Igor Vereš
MRMichal Ries
Michal Ries
IKIvan Kotuliak
Ivan Kotuliak

23 May 2025 in IEEE Access
Verified
Journal Article
Open access
WBWilliam Brach
William Brach
KKKristián Košťál
Kristián Košťál
MRMichal Ries
Michal Ries
The exponential growth of unstructured text data presents a fundamental challenge in modern data management and information retrieval. While Large Language Models (LLMs) have shown remarkable capabilities in natural language processing, their potential to transform unstructured text into standardized, structured formats remains largely unexplored - a capability that could revolutionize data processing workflows across industries. This study breaks new ground by systematically evaluating LLMs’ ability to convert unstructured recipe text into the structured Cooklang format. Through comprehensive testing of four models (GPT-4o, GPT-4o-mini, Llama3.1:70bLlama3.3:70b, and Llama3.1:8b), an innovative evaluation approach is introduced that combines traditional metrics (WER, ROUGE-L, TER) with specialized metrics for semantic element identification. Our experiments reveal that GPT-4o with few-shot prompting achieves breakthrough performance (ROUGE-L: 0.8209, WER: 0.3509), demonstrating for the first time that LLMs can reliably transform domain-specific unstructured text into structured formats without extensive training. Although model performance generally scales with size, we uncover surprising potential in smaller models like Llama3.1:8b for optimization through targeted fine-tuning. These findings open new possibilities for automated structured data generation across various domains, from medical records to technical documentation, potentially transforming the way organizations process and utilize unstructured information. For further information, source code, and associated resources, please refer to the source code repository (https://github.com/fiit-ba/text-to-cooklang).

19 April 2019 in Sensors
Verified
Journal Article
Open access
KKKristián Košťál
Kristián Košťál
RBRastislav Bencel
Rastislav Bencel
MRMichal Ries
Michal Ries
PTPeter Truchly
Peter Truchly
Ivan KotuliakIvan Kotuliak
Ivan Kotuliak
Wireless Local Area Network (WLAN) infrastructure is a dominant technology for direct access to the Internet and for cellular mobile data traffic offloading to WLANs. Additionally, the enterprise infrastructure can be used to provide functionality for the Internet of Things and Machine to Machine scenarios. This work is focused on improvements of radio resources control scalability similar to mobile networks via handover between cells. We introduce an improved IEEE 802.11 architecture utilizing Software-Defined Networks (SDNs). The proposed architecture allows communications during device movements without losing a quality of service (QoS). The fast seamless handover with QoS enables efficient usage of radio resources in large networks. Our improvements consist of integrating wireless management to OpenFlow protocol, separating encryption and decryption from an access point. In parallel, this feature as a side effect unloads processing at the Access Points (APs). Finally, the functionality of architecture design and scalability was proven by Colored Petri Nets (CPNs). The second proof of our concept was performed on two scenarios. The first scenario was applied to a delay sensitive use case. The second scenario considers a network congestion in real world conditions. Client’s mobility was integrated into both scenarios. The design was developed to demonstrate SDN WLAN architecture efficiency.