• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.4
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• pp.157-166
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• 2022

The most commonly used wireless communication technologies in IoT technology include ZigBee, WiFi, Bluetooth, and Z-Wave. In particular, Z-Wave is currently one of the preferred wireless communication technologies, with a global market share of 60 % of these technologies. In this research, a temperature and humidity sensor module using a Z-wave protocol was designed and manufactured by referring to the data sheet. Subsequently, the Z-Wave protocol was analyzed during the operation of the sensor module, and the firmware of the controller module was mounted and implemented. In addition, a program for monitoring the temperature and humidity information from the sensor module was developed and validated. Finally, the performance of the sensor module was validated through master distance and low power tests on it and its reception data success rate.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.594-597
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• 2015

IoT(Internet of Thing) 환경이 도래하면서 다양한 무선 통신 기술들이 사용되고 있다. 그 중에서 가장 많이 쓰이는 무선 통신 기술은 Z-WAVE이다. Z-WAVE는 저전력, 양방향 RF 등의 장점을 가지며, 세계 스마트 홈 시장에서 가장 폭 넓게 사용되는 기술이다. 이 기술을 채택한 연합을 Z-WAVE 연합이라고 하는데, 이 연합은 수백 개 이상의 제조사들과 1000개 이상의 활성화된 제품을 가지고 있다. 하지만 Z-WAVE는 중간자 공격 등과 같은 보안성의 취약점을 가지고 있으며 아직까지 연구가 부족한 실정이다. 따라서 본 논문에서는 IoT 환경에서 Z-WAVE 기반의 향상된 키 교환 프로토콜 기법을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2206-2211
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• 2012

To identify the effect of the aroma foot spa on the stress, 12 university students with stress were divided into control group (6 subjects) and aroma foot spa group (6 subjects). Control group was not subjected to any kind of intervention while aroma foot spa group was subjected to 10 minutes of foot bath using 5% Juniper, lavender and lemon essential oil and 10 minutes of foot massage using massage cream during four weeks, two times per week. As for the evaluation method, brain wave was studied to measure the amount of change in stress. After measuring the change in the brain wave before and after the experiment, it was proven that the aroma foot spa group s Alpha wave (Z=-2.364, p<.05) and SMR wave (Z=-1.981, p<.05) were higher than those of the control group. Moreover, when the pre and post experiment results of the aroma foot spa group were measured, it was proven that the Theta wave (Z=-2.366, p<.05) decreased while Alpha wave (Z=-2.371, p<.05) increased. In other words, aroma foot spa that included foot bath using essential oil and foot massage increased Alpha wave which in turn influenced the brain wave due to increased blood circulation resulting from muscle relaxation. Moreover, SMR wave increase was closely related to the change in Alpha wave, which demonstrates that SMR wave increased due to stress alleviation. Accordingly, it may be possible to assume that aroma foot spa is effective in relieving stress.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1198-1206
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• 2011

In this paper, we proposed a home network integrated dimmer switch using Z-wave Mesh Network. The dimmer switch come with wired and wireless network-based intelligent lighting switch that can be installed in a apartments with home network technologies. This switch is ease to install and operate. Furthermore, it provide power saving through efficient control of light using motion detect sensor and light intensity sensor. In order to evaluate the performance of our developed home network integrated dimmer switch, we performed a load performance test and from our result, it showed excellent performance in terms of lighting control and communication speed.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.463-465
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• 2017

ICT기술이 빠르게 발전함으로써 헬스케어, 스마트홈, 스마트 씨티, 스마트카, 웨어러블과 같이 다양한 인간중심의 서비스가 개발되고 있다. 이러한 인간중심 서비스를 제공하기 위해 여러 센서들을 이용하여 작은 네트워크를 구현한다. 일반적으로 많은 무선 프로토콜 중 Z-Wave를 많이 사용한다. 센서들의 정보를 AES기반으로 암호화하여 Controller와 Device간 통신하는데 가장 효율적이지만 Z-Wave통신으로 데이터를 보내기위해 암호화 키를 생성할 때 사용되는 값이 평문으로 전송되기 때문에 보안위협이 존재한다. 따라서 이러한 보안 위협을해결하기 위해 Controller와 Device간 암호화 키를 생성할 시 Diffie-Hellman을 이용하여 보다 안전한 프로토콜을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1256-1262
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• 2016

As the population of camping is increased in campsites and auto camp sites, the electrical equipment can safely supply electricity to users in a variety of electricity bill policy is required in the campsite. In this paper, we develop the vending machine for electricity that can control the outdoor electrical outlet from the management server using the Z-Wave WPAN and android mobile application. The developed vending machine for electricity consists of the management server, the controller, the outdoor outlet box, and the mobile application. The management server provides reservation and electricity bill payment to users. The management server controls the electrical outlet box through the controller to safely supply electricity to users. The controller that is a relay device between the management server and the switch controls switches based on Z-Wave mesh network. Outdoor electrical outlet box has 2 meter switches. We receive the relevant authorization to provide commercial electricity services using the outdoor electrical outlet box in the campsite.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1239-1245
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• 2009

Currently, so many approaching methods are being developed to optimize the antenna size. In this paper, We fabricated Inverted-F type antenna attaching lumped components to solve the limitation of antenna size. Through experiments, a basic Inverted-F type antenna was fabricated and satisfied the adequate radiation pattern. After this, we researched the effect of antenna varied by matching circuit consist of chip type resistor, inductor, and capacitor. Using that elements, the antenna was matched at aim frequency. The proposed antenna's size is $7\;{\times}\;24\;mm$ that is very small size against the resonance frequence. Measuring the developed antenna, Its return loss was -18dB. Thus, this antenna can be used for Z-wave systems.

• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.77-86
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• 1996

We employ the SOR method to analyze CPW electrodes of Ti:$LiNbO_3$ Mach-Zehnder traveling-wave optical modulator in the tapered region of an optical modulator. In the tapered region of the modulator, we design the electrodes satisfying $Z_c=50{\Omega}$. In the modulation region, we find two find sets of design parameters. One set is for $Z_c=50{\Omega}$, $n_{eff}=2.26$ and the another is for $n_{eff}=2.2$, $Z_c=47.7{\Omega}$.

• Journal of Korea Multimedia Society
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• v.23 no.3
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• pp.421-429
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• 2020

Recently, with the development of IoT technology and the increase of energy consumption, interest in energy saving and energy efficiency improvement is rapidly increasing. In particular, in the case of a device connected to a power plug with the power shutoff, a problem with standby power has been raised. Thus technology development through a low power method such as Zigbee is in progress. However, Zigbee, which is generally used, has a problem that a separate gateway is required because it is not an IP-based technology, and there is a problem that it is not suitable for a traditional computer network to which a variety of devices are connected. Therefore, in this paper, we designed and implemented a standby power saving system using MQTT, an IoT standard protocol, in Z-Wave environment. In order to evaluate the implemented standby power saving system, the same environment as the existing Zigbee-based standby power saving system was compared and evaluated.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.171-175
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• 2014

In this study, we suggest a method to measure the thickness of thin films nondestructively using the dispersion characteristics of a surface acoustic wave propagating along the thin film surface. To measure the thickness of thin films, we deposited thin films with different thicknesses on a Si (100) wafer substrate by controlling the deposit time using the E-beam evaporation method. The thickness of the thin films was measured using a scanning electron microscope. Subsequently, the surface wave velocity of the thin films with different thicknesses was measured using the V(z) curve method of scanning acoustic microscopy. The correlation between the measured thickness and surface acoustic wave velocity was verified. The wave velocity of the film decreased as the film thickness increased. Therefore, thin film thickness can be determined by measuring the dispersion characteristics of the surface acoustic wave velocity.