• 말소리와 음성과학
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• 제10권3호
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• pp.1-8
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• 2018

The vowel /o/ in Seoul Korean has been undergoing a sound change by altering the acoustic weighting of F2 and F1. Studies documented that this on-going change redefined the nature of a /o/-/u/ contrast as F2 differences rather than as F1 differences. The current study examined two cognitive factors namely executive function capacity (EF) and autistic traits, in terms of their roles in explaining who in speech community would adapt new acoustic forms of the target vowels, and who would retain the old forms. The participants, 55 college students speaking Seoul Korean, produced /o/ and /u/ vowels in isolated words; and completed three EF tasks (Digit N-Back, Stroop, and Trail-Making Task), and an Autism screening questionnaire. The relationships between speakers' cognitive task scores and their utilizations of F1 and F2 were analyzed using a series of correlation tests. Results yielded a meaningful relationship in participants' EF scores interacting with gender. Among the females, speakers with higher EF scores were better at retaining F1, which is a less informative cue for females since they utilized F2 more than they did F1 in realizing /o/ and /u/. In contrast, better EF control among male speakers was associated with more use of the new cue (F2) where males still utilized F1 as much as F2 in the production of /o/ and /u/ vowels. Taken together, individual differences in acoustic realization can be explained by individuals' cognitive abilities, and their progress in the sound change further predicts that cognitive ability influences the utilization of acoustic information which is non-primary to the speaker.

• Journal of Advanced Marine Engineering and Technology
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• 제37권6호
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• pp.638-643
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• 2013

유압시스템의 출력밀도를 높이기 위해 고압화, 대형화 되고 있으나, 유압동력 발생장치(HPU)를 구동할 때 110 dB(A) 정도의 높은 소음이 발생한다. 최근 산업안전규제 강화와 작업장 환경개선 요구 등으로 인하여 HPU의 소음저감을 위한 방안으로 실외나, 지하에 별도의 설치공간을 만들어 HPU를 이용하는 경우가 있었으나, 배관에서의 작동유 유동마찰로 인한 동력손실과 고장 났을 때 신속하게 대응하는데 문제가 있었다. 본 연구에서는 HPU의 동력변환 과정에서 필수적으로 발생되는 소음을 효과적으로 차폐시키면서 동력손실을 저감시키는 방음챔버(chamber)를 채용하여 소음특성을 개선하는 연구를 실험적으로 하였다.

• Journal of Biosystems Engineering
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• 제36권6호
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• pp.434-443
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• 2011

A large scale seeding system was stable in terms of techniques but a convenient seeding system of small size was unsettled. This study was performed to develop a semi-automatic seeder for small and medium sized scale farm. To investigate optimum needle diameter and vacuum pressure was used vacuum suction needle seeder. Although the needle diameter according to the kinds of seed was different, the needle diameter for salvia and lettuce seed was suitable for 0.34 mm needle nozzle and 0.4 mm taper nozzle. The prototype consisted a seeding frame attached with needle nozzle, seed hopper, vibrating device, seeding part, vacuum ejector, seed tube etc.. As the result with the experiments, the seeding rate of the seeder was 92% and more at 0.34 mm diameter needle nozzle and 0.4 mm taper nozzle. Eccentric weight for seed hopper vibration was suitable that weight is 11 g and eccentric distance is 0.5 mm. Vibration acceleration of upward direction was 0.363 m/$s^2$. Working capacity of the seeder was possible 160 trays per hour. It was possible for sowing small seeds but it was required to make compact and simple model.

• 한국토양비료학회지
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• 제17권4호
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• pp.381-388
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• 1984

객토원(客土源)을 구(求)하기 어려운 평야지(平野地) 사질답(砂質畓)의 토양개량제(土壤改良劑)로서 객토대체자원(客土代替資源)으로 Zeolite 시용(施用)의 가능성(可能性)을 검토(檢討)하기 위하여 포장시험(圃場試驗)과 실내시험(室內試驗) 결과(結果)를 요약(要約)하면 다음과 같다. 1. 점토함량(粘土含量) 16%인 토양(土壤)에 규산(珪酸)을 적량시용(適量施用)하고 질소(窒素)를 흡착(吸着)시킨 Zeolite 시용(施用)은 벼 생육(生育) 및 수량(收量)에 있어 객토(客土) 40M/T/10a 시용(施用)과 동등(同等)한 효과(效果)가 인정(認定)되었다. 2. 최고수량(最高收量)을 낸 질소시용량(窒素施用量)은 무개량구(無改良區), 객토(客土), Zeolite구(區)에서 각각(各各) 15.0, 18.2, 18.1kg/10a 이었다. 3. 객토구(客土區)와 Zeolite구(區)에서 수확기(收穫期) 질소(窒素) 및 $SiO_2$, 흡수량(吸收量)이 무개량구(無改良區)에 비(比)해 현저(顯著)히 많았다. 4. 토양(土壤), 객토원(客土源) 및 Zeolite의 암모늄 흡착양상(吸着樣相)은 Langmuir 등(等) 온흡착식(溫吸着式)을 따랐고 암모늄 최대흡착(最大吸着)은 각각(各各) 16.7, 20.5, 890mg/10a이었다.

• 보건교육건강증진학회지
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• 제15권2호
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• pp.43-53
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• 1998

The National Health Promotion Law passed in 1995 was a milestone for initiating a national health promotion program in Korea, and government officers and health professionals are working on how to approach health promotion issues. The purpose of this study was to analyse methods and use of constructivist paradigm in health promotion and education. The health promotion area needs community empowerment, building community partnerships, and community capacity. To meet these health promotion requirements health promotion workforce should be trained through professional preparation programs that contains communication skills, group process skills, and management of programs in advanced countries such as the United States and Australia. Skills and responsibilities of those who are in charge of providing health promotion services have not yet been clearly defined in Korea because the area of health promotion is a multi-academic field, and needs a different approach, constructivist approach. Constructivist paradigm requires relativism, reasoning skills, collaborating, and motivation. These components are needed for community empowerment. Constructivism also has been applied to the field of education. Problem-based education, outcome-based education, performance-based education came from the constructivism. These educational methods are student-centered method. As the modernizing society becomes more complicated, traditional or conventional teacher-centered education cannot meet the needs of students. Students need to learn skills necessary to make healthy decisions with individual value system. So these interactive, self-learning methods can serve much more to the learner. Constructivist educational methods can be applied to educational programs in computers, too. To expand and differentiate the area of health education and health promotion from other health related fields, it is crucial to devote efforts in application and development of constructivist methods.

• 한국안전학회지
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• 제27권4호
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• pp.101-107
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• 2012

The statistics of industrial accident reported by ministry of Employment and Labor denoted a significant increase of musculoskeletal disorders(MSDs) after 1993, and showed the higher incident rate by 71.3% over the overall worker's disorders. Also, it was expected that Korean society will become the post-aged society in 2026 with 20.8% of elderly who is over 65 years old. The reports suggest possible problems caused by the older worker known to have reduced working ability than the young counterparts. On this basis, the goal of this study was to investigate the relationship between MSDs symptoms and work ability in the shipbuilding industry. To achieve this goal, this study distributed a questionnaire for total 1,244 shipbuilding employers, and used 910 employers' reports which revealed validity for this study. The questionnaire included the MSDs symptoms report developed by the Korean Occupational Safety and Health Association(KOSHA) and the work ability index(WAI) developed by Finnish Institute of Occupational Health(FIOH). Results showed no relationship between MSDs symptoms and age, years of work and exercise. Also, the work ability was increased until 44 years old, but it was decreased after that time because of the reduced physical capacity. Meanwhile, the years of work and exercise have positive correlation with work ability. However, the results revealed significant relationships between WAI and age, years of work, task characteristics and exercise. All together, the MSDs symptoms have a close relationship with the work ability in that the work ability of workers with the MSDs symptoms was reduced. This study may suggest the needs of more efforts and attention on the MSDs prevention to increase the work ability.

• Journal of Biosystems Engineering
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• 제34권1호
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• pp.21-29
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• 2009

A rapeseed reaping equipment attachable to a conventional combine was developed in order to harvest rapeseed for bio-diesel materials. This study was carried out to measure the harvest feasibility of a prototype combine in rapeseed fields. Grain, stem and pod flow rate, grain qualities (whole kernel, damaged kernel, unhulled kernel, material-other-than-grain) and grain loss rates (header, threshing, separation) were investigated in each field test. As the result of the fold test, the average grain flow rates of SUNMANG and MS varieties showed 1,430 kg/h and 2,038 kg/h, respectively. The average stem and pod flow rates showed 3,443 kg/h and 6,596 kg/h, respectively. In each working speed, the average whole kernel rate and the material-other-than-grain showed 99.9% and below 0.08%, respectively. In the average grain loss, the rates showed 5.66% in case of SUNMANG and 5.94% in MS. Header loss was higher than other parts for SUNMANG. However, threshing loss was relatively higher than other parts for MS. Header loss rate due to side cutter knifes, however, was not so high when compared with a grain loss due to the cutter bar. Effective field capacity and field efficiency of the prototype combine showed 0.389 ha/h and 44%, respectively. Comparison of customary combine with the prototype combine through field test demonstrated that the header loss was reduced by 69.3% when the prototype combine was used.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.138-144
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• 2016

Purpose: Phosphorus is an essential element for water quality control. Excessive amounts of phosphorus causes algal bloom in water, which leads to eutrophication and a decline in water quality. It is necessary to maintain the optimum amount of phosphorus present. During the last decades, various studies have been conducted to determine phosphorus content in water. In this study, we present a comprehensive overview of colorimetric, electrochemical, fluorescence, microfluidic, and remote sensing technologies for the measurement of phosphorus in water, along with their working principles and limitations. Results: The colorimetric techniques determine the concentration of phosphorus through the use of color-generating reagents. This is specific to a single chemical species and inexpensive to use. The electrochemical techniques operate by using a reaction of the analyte of interest to generate an electrical signal that is proportional to the sample analyte concentration. They show a good linear output, good repeatability, and a high detection capacity. The fluorescence technique is a kind of spectroscopic analysis method. The particles in the sample are excited by irradiation at a specific wavelength, emitting radiation of a different wavelength. It is possible to use this for quantitative and qualitative analysis of the target analyte. The microfluidic techniques incorporate several features to control chemical reactions in a micro device of low sample volume and reagent consumption. They are cheap and rapid methods for the detection of phosphorus in water. The remote sensing technique analyzes the sample for the target analyte using an optical technique, but without direct contact. It can cover a wider area than the other techniques mentioned in this review. Conclusion: It is concluded that the sensing technologies reviewed in this study are promising for rapid detection of phosphorus in water. The measurement range and sensitivity of the sensors have been greatly improved recently.

• Earthquakes and Structures
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• 제12권1호
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• pp.13-21
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• 2017

Recent seismic events occurred in Italy (Emilia-Romagna 2012, Abruzzo 2009) and worldwide (New Zealand 2010 and 2011) highlighted some of the weaknesses of precast concrete industrial buildings, especially those related to the connecting systems traditionally employed to fasten the cladding panels to the internal framing. In fact, one of the most commons fails it is possible to observe in such structural typologies is related to the out-of-plane collapse of the external walls due to the unsatisfactory behaviour of the connectors used to join the panels to the perimeter beams. In this work, the strengthening of a traditional industrial building, assumed as a case study, made by precast reinforced concrete is proposed by the adoption of a dual system allowing the reinforcement of the structure by acting both internally; by pendular columns and, externally, on the walls. In particular, traditional connections at the top of the walls are substituted by devices able to work as a slider with vertical axis while, the bottom of the walls is equipped with two or more hysteretic dampers working on the uplift of the cladding panels occurring under seismic actions. By means of this approach, the structure is stiffened; obtaining a reduction of the lateral drifts under serviceability limit states. In addition, its seismic behaviour is improved due to the additional source of energy dissipation represented by the dampers located at the base of the walls. The effectiveness of the suggested retrofitting approach has been checked by comparing the performance of the retrofitted structure with those of the structure unreinforced by means of both pushover and Incremental Dynamic Analyses (IDA) in terms of behaviour factor, assumed as a measure of the ductility capacity of the structure.