• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1326-1331
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• 2006

Weld root gap is a important fact of a falling-off weld quality in various kind of weld defect. The welding quality can be controlled by monitoring important parameters, such as, the Arc voltage, welding current and welding speed during the welding process. Welding systems use either a vision sensor or an Arc sensor, both of which are unable to control these parameters directly. Therefore, it is difficult to obtain necessary bead geometry without automatically controlling the welding parameters through the sensors. In this paper we propose a novel approach using neural networks for detecting and monitoring of weld root gap and bead shape. Through experiments we demonstrate that the proposed system can be used for real welding processes. The results demonstrate that the system can efficiently estimate the weld bead shape and detect the welding defects.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.9
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• pp.1-12
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• 1998

We have implemented receiver for a 3 Dimensional Phased-Array Radar detecting the azimuth angle, the altitude, the range of a target on real time. This system consists of high frequency module, which protects receiver and controls sensitivity, intermediate frequency module, monopulse detector, IQ phase detector, AGC controller. A two-channel receiver with same function is implemented for increasing accuracy of target altitude data by amplitude comparison monopulse method. The TSS sensitivity of the receiver is -98dBm. The bandwidth of the receiver is 500 MHz. We can control the system gain manually by 100 dB when be AGC off. The gain and phase unbalance of two channels is 5 dB and 30 degree, respectively. The image rejection rate of the IQ detector is 30 dB. We used duroid substrate and package- type device.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.51-55
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• 2007

Generally, PLC (Power Line Communication) based home automation devices such as wall switch, walt socket, gas controller, etc, must maintain wake-up status at all time to control other electronic devices and monitor their on/off status whether they are in service or not. In order to reduce the unnecessary energy consumption during the standby mode, the new power-saving PLC 2 ports wall switch has been developed, separating PLC communication part and controller part and introducing sleep mode. In addition, to expand life cycle of PLC product and to reduce the rate of product failure in active mode, the instant controlling method in controlling process is adopted instead of the maintenance controlling method. In comparison to the earlier model, the new 2 ports PLC wall switch has reduced power by 0.95[W] less in standby mode and 3.2[W] less in active mode than the previous one.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.137-143
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• 2015

Fire fighter are exposed to the situations which are hard to predict due to continuous and accidental changes which hinder their fire fighting activity. As these threats of safety accident act as fear factors, they are doing insecure fire fighting activities. Therefore, as unclear and abnormal risks of working environment such as the riskiness of expansion of disaster, instability, obstacles of activities, abnormality, urgency, etc. increase, safety accidents are caused. This study analyzes the actual condition of safety and health and awareness of fire fighter who are exposed safety accidents during their fire fighting activities and utilize such result as the basis data to secure safety of fire fighter, keep efficient safety control and prevent accidents. The results of analysis are as follows. As rescue works among all fire-fighting works shows the highest emotional stabilization and the highest post-traumatic stress disorder is shown in fire sergeant level positions, and fire fighters whose working period is 10-15 years, reinforcing safety training to long-term workers is necessary. As the result of survey regarding safety awareness, the highest awareness level was shown in fire sergeant level positions, and fire fighters whose working period is over 20 years, and when it comes to operation of fire fighting equipments, fire-fighting workers and workers having 1-4 years of working period showed high safety awareness. The more serious injury in a fire fighter experienced as the first injury after working as a fire-fighter, the more cause-and-effect relationship was shown between personal physical condition and work, and it is shown as obstacles of fire fighting activities and affects to post-traumatic stress disorder. Moreover, as after-work off duty activities also affect to official disaster, systematic improvement of working environment is required. Occupational medical work compatibility evaluation considering the distinct characteristics of works to secure fire-fighter' health care together with fire-fighting capability is shown to be necessary.

• Archives of Plastic Surgery
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• v.43 no.6
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• pp.570-574
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• 2016

Background Fractional $CO_2$ laser is an effective treatment for scars, but most patients complain about sharp burning pain, even after the application of lidocaine ointment. This study analyzed the impact of a vibrating device to nonpharmacologically reduce the acute pain of laser treatment, in accordance with the gate control theory of pain management. Methods This is a prospective study performed from May 2013 through March 2014. Fifty-three patients (mean age, 26.7 years; range, 16-44 years) who had donated livers for liver transplantation were treated with a fractional $CO_2$ laser (10,600 nm; model $eCO_2$, Lutronic Corp) for their abdomen scars. Laser treatment was applied 4 months after surgery. A commercially available, locally applied vibrating device (model UM-30M, Unix Electronics Co. Ltd.) was used, in an on-and-off pattern, together with the $CO_2$ laser. A visual analogue scale (VAS; 0, no pain; 10, most severe pain) of pain sensation was assessed and statistically analyzed using a paired t-test. Results The average VAS score for pain with the vibrating device was 4.60 and the average VAS score without the vibrating device was 6.11. The average difference between scores was 1.51 (P=0.001). Conclusions A locally applied vibrating device was demonstrated to be effective in reducing pain when treating with a fractional $CO_2$ laser. Vibration treatment could be helpful when treating scars with fractional $CO_2$ laser in pain-sensitive patients, particularly children.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.136.2-136.2
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• 2015

반도체 제조는 chip의 성능 향상 및 단가 하락을 위해 지속적으로 pattern size가 nano size로 감소해 왔고, capacitor 용량은 증가해 왔다. 이러한 현상은 contact hole의 aspect ratio를 지속적으로 증가시킨바, 그에 따라 최적의 HARC (high aspect ratio contact)을 확보하는 적합한 dry etch process가 필수적이다. 그러나 HARC dry etch process는 많은 critical plasma properties 에 의존하는 매우 복잡한 공정이다. 따라서, critical plasma properties를 적절히 조절하여 higher aspect ratio, higher etch selectivity, tighter critical dimension control, lower P2ID과 같은 plasma characteristics을 확보하는 것이 요구된다. 현재 critical plasma properties를 제어하기 위해 다양한 plasma etching 방법이 연구 되어왔다. 이 중 plasma를 낮은 kHz의 frequency에서 on/off 하는 pulsed plasma etching technique은 nanoscale semiconductor material의 etch 특성을 효과적으로 향상 시킬 수 있다. 따라서 본 실험에서는 dual-frequency capacitive coupled plasma (DF-CCP)을 사용하여 plasma operation 동안 duty ratio와 pulse frequency와 같은 pulse parameters를 적용하여 plasma의 특성을 각각 제어함으로써 etch selectivity와 uniformity를 향상 시키고자 하였다. Selective SiO2 contact etching을 위해 top electrode에는 60 MHz pulsed RF source power를, bottom electrode에는 2MHz pulse plasma를 인가하여 synchronously pulsed dual-frequency capacitive coupled plasma (DF-CCP)에서의 plasma 특성과 dual pulsed plasma의 sync. pulsing duty ratio의 영향에 따른 etching 특성 등을 연구 진행하였다. 또한 emissive probe를 통해 전자온도, OES를 통한 radical 분석으로 critical Plasma properties를 분석하였고 SEM을 통한 etch 특성분석과 XPS를 통한 표면분석도 함께 진행하였다. 그 결과 60%의 source duty percentage와 50%의 bias duty percentage에서 가장 향상된 etch 특성을 얻을 수 있었다.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.7-13
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• 2006

Linear compressors with a free piston driven by a linear motor are widely attention in the cooling apparatus such as refrigerator due to the high efficiency The stroke of piston in the linear compressor driven by LPMSM (Linear Permanent-Magnet Synchronous Motor) can be obtained from Integrating the input voltage and current of LPMSM, but it may be diverged due to dc components in the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and do offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The accurate stroke of a piston can be calculated by compensating for dc offset. The performance of the newly developed stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.587-592
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• 2004

This research was aimed to manufacture the cholesterol free Mozzarella cheese with corn oil that contains high unsaturated fatty acid helping the reduction of serum cholesterol. Cheese stored at 1$0^{\circ}C$ was evaluated with general analysis, volatile free fatty acid, cholesterol, meltability, stretchability, color, rheological properties, and sensory evaluation. Moisture contents decreased during cheese storage period, whereas protein contents and pH value increased significantly (P < 0.05), but fat contents did not show any significant change. Linoleic acid was tile main volatile free fatty acid in a fat of cheese, and cholesterol contents were measured 4.34$\pm$ 0.04 mg/100 g in cheese. The meltability of cheese gradually increased during ripening, while the stretchability decreased. The color of cheese showed translucent yellow. Hardness, springiness, and cohesiveness increased significantly up to 21 days of storage. Compared to control cheese made by conventional way, QDA scores of shiny, oiling off, and melting of cholesterol free cheese were significantly different. These results suggested that health-oriented cholesterol free Mozzarella cheese would be made by addition of the corn oil.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1824-1827
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• 2005

For application to micro fluid control systems such as ${\mu}TAS$ (Micro Total Analysis Systems) and DDS (Drug Delivery Systems), it is very significant to handle precise and minute flow rates with low pressure pulsation. In this study, a novel valveless piezoelectric pump using peristaltic motion with three disk type PZT actuators is presented. The newly devised pump with an effective size of $70mm{\times}60mm{\times}55mm$ has three actuator layers connected in series from inlet to outlet. The PZT actuator has a maximum displacement of 240 ${\mu}m$ and a maximum force of 1.6 N. When the driving voltage for PZT actuators is sequentially applied with a certain phase shift, the pumping is performed by peristaltic motion of liquid volume. The working fluid is shut off without the driving voltage. Three methods for sequential driving are proposed and experimentally investigated. First and second methods utilize an intermittent sinusoidal waveform with phase shift of $90{\circ}\;and\;120^{\circ}$, respectively. Third method uses a rectangular waveform with phase shift of $90^{\circ}$. A controller with multi-phase shifter is designed and fabricated. Then, frequency and voltage-flow rate characteristics and load pressure-flow rate characteristics are experimentally investigated to verify the validity of the developed pump.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.145-151
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• 2009

Recently the water quality management policy has been changed from managing the point source to controlling the nonpoint sources (NPSs) because of TMDL program. Most NPSs are accumulated on the surface during dry periods. These accumulated pollutants are washed-off during a storm event and highly impairing the water quality of the receiving water bodies. Usually NPS has high uncertainty and is hard to control because of the variability of the rainfall and watershed characteristics. Also, NPS is derived from various land uses. The Ministry of Environment (MOE) is studying and monitoring the pollutant loads from each land use since 2007 to determine the unit pollutant loads. This research was a part of long-term monitoring program conducted to characterize the washoff and provide the mean EMC of artificial grassland. The average EMCs result of BOD, COD, DOC, SS, TN, NH4-N, NO3-N, TP, and PO4-P of the artificial grassland were deterined to 8.2, 17.5, 11.3, 110.1, 3.07, 0.20, 0.75, 0.86 and 0.08 mg/L, respectively. The results of statistical analysis conducted showed a low correlation to the contaminants.