• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.192-195
• /
• 2005

The silicon thin film solar cells were fabricated by 13.56 MHz PECVD (Plasma-Enhanced Chemical-Vapor Deposition) and 60 MHz VHF PECVD (Very High-Frequency Plasma-Enhanced Chemical-Vapor Deposition). We focus on textured ZnO:Al films prepared by RF sputtering and post deposition wet chemical etching and studied the surface morphology and optical properties. These films were optimized the light scattering properties of the textured ZnO:Al after wet chemical etching. Finally, the textured ZnO:Al films were successfully applied as substrates for silicon thin films solar cells. The efficiency of tandem solar cells with $0.25 cm^2$ area was $11.8\%$ under $100mW/cm^2$ light intensity. The electrical properties of tandem solar cells were measured with solar simulator (AM 1.5, $100 mW/cm^2)$ and spectral response measurements.

• Korean Journal of Community Nutrition
• /
• v.16 no.5
• /
• pp.548-558
• /
• 2011

The purpose of this study was to compare eating habits and food attitudes between depressed and normal adults. The subjects were selected (n = 6217) from those who participated in the 2008 Korean National Health and Nutrition Examination Survey (KNHANES IV). The subjects were divided into the depressed (DG, n = 841) and normal groups (NG, n = 3969). DG was those who have depression now or who have experienced depressing feelings more than two weeks or per year. The general characteristics, anthropometric measurement, eating habits, the dietary guideline recognition and practices were compared by using chi-square test and t-test. Also the partial correlations were analyzed by SAS (Statistical analysis system, version 9.1) program. There was a significantly higher rate of DG among the female (74.32%), with low education (44.6%) and low-income (32.0%) subjects (p < 0.001). DG showed significantly lower snacking and dining out. There was significantly higher rate of DG who responded "none" in frequency of snack (27.10%) and dining out (29.50%) (p < 0.001). Also DG showed significantly lower rate of the subjects who ate with the family than NG. Also, DG showed significantly lower dietary guideline recognition level and practice than NG. Correlation between depression symptom and various factors showed that positive correlation with low snack intake and dining out frequencies. However, correlation was relatively weak. In conclusion, eating habits and recognition levels and practice of dietary guidelines of DG were significantly different from NG. DG showed significantly lower frequencies of snack, dining out, and eating with family.

• The Korean Journal of Food And Nutrition
• /
• v.27 no.5
• /
• pp.771-784
• /
• 2014

The purpose of this study was to estimate the relationships between dietary factors and the stress perception levels of College students. A survey was conducted in June, 2010, targeting 332 college students in Gwangju. General environmental factors, stress perception levels, dietary behaviors, and dietary action guide performance of the subjects were evaluated by questionnaire, and food intakes was determined by the 24-hour recall method. The results are summarized as follows.: The score of frequency experiencing was $45.1{\pm}16.9$ for male students, and $47.0{\pm}16.7$ for female students. The importance scores were $50.8{\pm}18.5$ for males, and $53.3{\pm}18.7$ for females. The total score for dietary action guide performance was $39.6{\pm}7.2$ for males and $40.6{\pm}6.5$ for females. Nutrient intake levels were evaluated based on dietary reference intake (DRI), revealing energy intakes to be 68.5% EER in males and 73.9% in females. The mean intakes of nutrient were 54.2% RI for calcium, 73.6% RI for riboflavin, and 51.2% RI for vitamin C but 203.6% AI for sodium, which indicates an imbalance in nutrient intake. Analysis of the correlations between stress perception levels and dietary factors, scholarship achievements, financial problems, future problems, value senses, and family relationships revealed significant correlations with general environment factors, dietary behaviors, Dietary action guide performance, and nutrient intakes (p<0.05). The higher the stress perception levels of the students, the higher the energy, coffee and alcohol intake, which predicts that appropriate stress control in college students will lead to better dietary habits. It is expected that the results above will be used as basic data for the development of proper nutrition education programs and stress control strategies.

• Asian-Australasian Journal of Animal Sciences
• /
• v.19 no.6
• /
• pp.793-798
• /
• 2006

The quality characteristics of semen are important indicators of the fertility of a boar. Development of genetic markers for the semen quality in boars will be beneficial to the improvement of porcine fertility. We investigated the relationship between the polymorphisms of epidermal growth factor (EGF), prostaglandin-endoperoxide synthase 2 (PTGS2) and prolactin receptor (PRLR) genes, and semen quality traits in boars. The genomic DNA of 233 boars (157 Duroc and 86 Landrace) from a central testing station was subjected to genotyping for surveying gene frequency. The EGF, PTGS2 and PRLR genotypes were determined using the restriction fragment length polymorphism method. Thirty-seven normal, mature Duroc boars from an AI center were also genotyped and their semen quality traits were collected. The effect of genotype on semen quality traits was analyzed by the least-squares means method using data corrected for season. The frequencies of the AA genotype of EGF, PTGS2 and PRLR in Duroc boars were 0.14, 0.01 and 0.66, respectively. In Landrace, the frequencies of the AA genotype were 0.03, 0.09 and 0.62, respectively. Boars with the BB genotype in EGF, with the AB genotype in PTGS2 and with the AA genotype in PRLR had significantly better semen quality with a higher percentage of normal sperm and a lower percentage of immature sperm than those with other genotypes. These findings imply that polymorphisms of EGF, PTGS2 and PRLR genes might be used as markers for improving the semen quality of boars.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.24 no.3
• /
• pp.310-315
• /
• 2014

The domestic maritime environment shows higher frequency of maritime accidents amidst greater traffic volume arising from increasing international seaborne trade and maritime leisure activities. To reduce such maritime accidents, there exist various kinds of safety navigation devices in the ship bridge aimed to mitigate burdens of navigators and support their accurate decision making. Amongst is the AIS considered very important, which is an automatic tracking system to assist understanding of the circumstances in the vicinity by receiving information of other ships and also sending its own; where the information contains errors initially, however, such wrong information is periodically transmitted, accordingly giving rise to hindrance sometimes in decision making by shore operators or ship navigators at sea. This study is to propose the error data and field management algorithm using fuzzy theory toward improving reliability and accuracy in ship related information received from AIS.

• The Journal of the Acoustical Society of Korea
• /
• v.39 no.5
• /
• pp.454-460
• /
• 2020

Artificial intelligence assistants that provide speech recognition operate through cloud-based voice recognition with high accuracy. In cloud-based speech recognition, Wake-Up-Word (WUW) detection plays an important role in activating devices on standby. In this paper, we compare the performance of Convolutional Neural Network (CNN)-based WUW detection models for mobile devices by using Google's speech commands dataset, using the spectrogram and mel-frequency cepstral coefficient features as inputs. The CNN models used in this paper are multi-layer perceptron, general convolutional neural network, VGG16, VGG19, ResNet50, ResNet101, ResNet152, MobileNet. We also propose network that reduces the model size to 1/25 while maintaining the performance of MobileNet is also proposed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.12
• /
• pp.2836-2842
• /
• 2010

An NPC grouping method is proposed for various 3D games depending on their characteristics. Immovable objects tend to have particular orientation features in their Gabor filtering results whereas the movable objects controlled by AI appearing as a human or an animal do not. First of all, We analyzed directional and frequency domain features in the NPC object and configured them as 24 Gabor filter banks. Then, 24-dimensional feature vectors according to the scale and direction of the filter are calculated. Each extracted vector represents the energy of a certain direction. This energy indicates the particular direction strength of the object texture. Thus, using this property, NPCs could be grouped as artificial objects and natural objects effectively and it draws the game more speed and strategic actions as a result.

• The Journal of the Acoustical Society of Korea
• /
• v.37 no.3
• /
• pp.129-138
• /
• 2018

In port and coastal areas where ship traffic is frequent, ship noise dominantly influences underwater noise in low frequency band below 1 kHz. In this paper, we propose a modeling method to estimate the underwater shipping noise using the voyage information of ship observed in AIS (Automatic Identification System). For the purpose of ship noise modeling, the navigation information of the vessels operating in the southern part of Jeju was observed using AIS and underwater noise was measured by installing a hydrophone in the experimental area to verify the modeled ship noise. AIS data were used to model the noise level of ship and compared with measured underwater noise. The variation of noise level with time was found to be similar, and the cause of the error was discussed. Through this study, it was confirmed that the noise level of ship can be estimated within 5 dB error range using AIS data.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.9 no.1
• /
• pp.25-34
• /
• 2010

Fretting damage reduces fatigue life of the material due to low amplitude cyclic sliding and changes in the contact surfaces of strongly connected machine and structures such as bolt, key, fixed rivet and connected shaft, which have relative slip of repeatedly very low frequency amplitude. In this study, the fretting fatigue behavior of 7050-T7451 aluminum alloys used mainly in aircraft and automobile industry were evaluated. The plain fatigue test and fretting fatigue test under cyclic bending load carried out commercial bending fatigue tester and specially devised equipments to cause fretting damage. From these experimental work, the following results obtained: (1) The plain fatigue limit for stress ratio R=-l was about 151MPa. (2) In case of fretting fatigue, fatigue limit for stress ratio R=-l about 72MPa, the fatigue limit for R=0 about 81MPa, and the fatigue limit for R=0.3 about 93MPa. (3) The fatigue limit reduction rates by the fretting damage were about 52%(R=-1), 46%(R=0) and 38%(R=0.3) respectively. (4) The fatigue limit reduction rate decreased with stress ratio increase. In fretting bending test, as stress ratio increased, occurrence of initial oblique crack by fretting decreased or phased out, so that fracture surfaces were formed by plain fatigue crack occurrence, and such tendency was notable as stress amplitude increased. (5) Tire tracks and rubbed scars were observed in the fracture surface and contacted surface.

• Korean Journal of Community Nutrition
• /
• v.16 no.1
• /
• pp.75-85
• /
• 2011

The purpose of this study was to investigate basic data on the degree of parents' recognition and satisfaction with the use of environment-friendly agricultural products. The conclusions of this study are as follows. The survey on the use of environment-friendly products in households showed that 68.7% of the respondents used environment-friendly products at home. The frequency of purchasing organic products by household consumers showed that 25.1% of the respondents bought organic products one to two times per week. The most popular items of the environment-friendly agricultural products used were vegetables, comprising 63.9%. The households with more than 3,000,000 won of monthly income tended to consume more domestic livestock products (p < 0.05). In comparison to general agricultural products, environment-friendly agricultural products users showed higher satisfaction level with a better quality in term of safety, quality, nutrition, taste, appearance, diversity and price. The degree of satisfaction with safety was the highest ($3.8{\pm}0.68$), and price showed the lowest ($2.76{\pm}0.79$). The degree of parents' recognition of the governmental support for environment-friendly agricultural products showed that those who were aware of the supporting policy were 44.5%, but 55.5% of them didn't know about the fact that 46.6% of the respondents agreed that environment-friendly agricultural products should be used in more than 50% of the foods used for school food service. The respondents pointed out that vegetables (45%) sprayed with pesticide are the most urgent food item that need to be replaced by environment-friendly farm products.