• Journal of the Korean Society of Propulsion Engineers
• /
• v.3 no.4
• /
• pp.44-50
• /
• 1999

For the prediction of combustion performance of the Unlike Impinging Quadlet Injector (OOOF type), mixing efficiency, mixing characteristic velocity, and efficiency of mixing characteristic velocity were obtained from the cold test. Water/kerosene were used for simulants, The momentum ratio of oxidizer and fuel were mixing correlating parameter. Orifice discharge coefficient, spray pattern and mass distribution were measured. As a result, invasion-depth had strong effect on mixing efficiency, mixing characteristic velocity, and efficiency of mixing characteristic velocity. Mixing efficiency and efficiency of mixing characteristic velocity showed maximum value for momentum ratio 1.67(TMR = 2.5), and fuel rich state showed larger decreasing ratio than oxidizer rich state.

• Korean Journal of Psychosomatic Medicine
• /
• v.14 no.1
• /
• pp.8-17
• /
• 2006

Neurofeedback, also known as EEG biofeedback or neurotherapy, is a new therapy differentiated from biofeedback in that brain waves are monitored to study brain itself as well as its functions. Needless to say, it has originated from biofeedback, however it has established itself as an independent and specialized therapy in the field of neurotherapy. In order to have a better understanding of neurofeedback we are going to have a look into its historical and theoretical background first and then we will explain how it can be used clinically. Neurofeedback was clinically introduced for epilepsy for the first time and its effect was proved. Since then it has been used successfully for a number of psychiatric disorders, such as attention deficit hyperactivity disorder(ADHD), anxiety, anxiety and mood disorder, sleep disorder, substance dependency, etc. Furthermore, it has been used for non-psychiatric or psychosomatic symptoms, such as headache, chronic pains, chronic fatigue symptoms, etc. Recently, it has been also used for non-medical areas, such as improvement of peak performance for sports and art activities, enhancement of cognitive function, etc, making the neurofeedback a very promising field for its potential and effectiveness.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.8 no.2
• /
• pp.217-231
• /
• 1997

This paper first reviewed the current neurological theories concerning the etiology of ADHD and secondly, examined results of studies that applied neuropsychological assessment methods in the examination of ADHD children both here in Korea and abroad. ADHD children were found to exhibit characteristic responses indicating deficits in vigilance, sustained attention, distractibility, allocation and regulation of attention in many assessments of attention, in addition to deficits in executive functioning, working and associative memory. Such neuropsychological assessment results suggest that in addition to dysfunction in the frontal lobe and the reticular activation system, dysfunction may exist in other neural pathways involving many areas of the brain. However, because a substantial number of neuropsychological assessment tools being employed in Korea for ADHD children had been developed abroad, a Korean standardization project involving ADHD and normal control children, in addition to other child psychiatric population pools must be conducted in order to obtain appropriate age norms and test validity, and in order to make possible a more accurate and precise comparison and interpretation in the assessment of ADHD children.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.25 no.4
• /
• pp.209-216
• /
• 2014

Objectives : Alcohol use disorder (AUD) is often comorbid with adult attention-deficit hyperactivity disorder (ADHD) and other psychiatric illnesses. When associated with other mental problems, the prognosis of the AUD can be more serious. This study shows research on the clinical and neuropsychological characteristics according to whether or not ADHD symptoms and AUD were comorbid. Methods : A total of 64 adult inpatients who completed AUD scales about adult ADHD, alcohol dependence, depression, anxiety, and impulsiveness. They also completed neuropsychological tests about attention and executive function. According to the Adult ADHD Self-Report Scale score, patients were categorized into two groups (ADHD symptom positive/negative group). Results : Fourteen among the 64 subjects were part of the ADHD symptom positive group (21.9%). They had statistically significant shorter abstinence periods and a higher rate of history of 'rule violation during school' and 'physical damage in childhood' compared to the ADHD symptom negative group. Conclusion : The comorbidity rate with ADHD symptom in adult AUD is higher than the general population. The ADHD symptom positive group suffered from more severe and refractory AUD. Considering the more frequent history of rule violation during school in the ADHD symptom positive group, the association between ADHD and AUD may be mediated by conduct disorder. Therefore we suggest the necessity of careful evaluation and intervention in children and adolescents with ADHD and conduct disorder.

• Environmental and Resource Economics Review
• /
• v.23 no.1
• /
• pp.43-65
• /
• 2014

In this paper, we test for allocative efficiency of productive inputs including electricity and measure the divergence between the actual and optimal level of electricity for the chemical products, which is a relatively highly electricity-intensive sector in Korean manufacturing industries, by estimating a shadow cost function. Supposing cost minimization subject to market prices was achieved, we derive the price elasticities of demand for each input and simulate the impact of a 10% increase in power rate on its demand and supply price by estimating jointly a cost function with an inverse supply relation. The null hypothesis of allocative efficiency of inputs is rejected over the period 1982-2006. On average, electricity is used more than optimal level by 98% per year. The demand for electricity decreases by 11.4%, and supply price, on average, falls by 0.08%, other things being equal.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.3
• /
• pp.105-112
• /
• 2002

Increases in excess pore water pressure without change of surcharge load were reported in clay underneath embankment at Berthierville and Olga sites after the end of construction. These abnormal phenomena could not be explained by classical consolidation theory. This paper presents a nonlinear viscoplastic model to interpret an increase in pore water pressure on natural clay, The proposed model can consider the combined processes of pore water pressure dissipation according to Darcy's law and pore water pressure generation due to viscoplastic strain, as well as time-dependent viscoplastic behaviour and strain rate dependency of preconsolidation pressure. The calculated results using numerical analysis are compared with measured ones under embankments built on soft clay at Berthierville and Olga in Quebec, Canada. It may be possible to explain the phenomenon of excess pore water pressure increase after the end of construction using the proposed nonlinear viscoplastic model.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.3
• /
• pp.141-147
• /
• 2007

Various approaches have been developed for the dynamic response analysis of piles. In one of the approaches, the soil-pile interaction is approximated by using parallel nonlinear springs, namely the p-y curves. Currently available p-y curve recommendations are based on static and cyclic lateral load tests. Other researchers have attempted to extend the p-y curves by incorporating the effects of liquefaction on soil-pile interaction and derived scaling factors of p-y curves to account fur the liquefaction. However, opinions on the scaling factors vary. In this study, the sealing factors, which reflect the variation of the elastic moduli of surrounding soils, were established combining the relationship between excess pore pressures and the natural frequencies of a soil-pile system obtained from Ig shaking table tests and the relationship between the elastic moduli of surrounding soils and the natural frequencies of a soil-pile system obtained from numerical analyses. As a result, the scaling factors were presented in an exponential function.

• The Journal of the Korea Contents Association
• /
• v.12 no.10
• /
• pp.330-339
• /
• 2012

The purpose of this study was to examine the relationship among children's ADHD symptoms, parenting stress and behavior regarding nurturing. The data were provided by 59 mothers of children with ADHD who is aged between 4 and 12. Mothers of children with ADHD were recruited through 3 departments of child psychiatry. The Korean version of Parenting Stress Index-Short Form, the Korean version of revised Maternal Behavior research Instrument(MBRI) and ADHD Rating Scale(K-ARS) was used to assess parenting stress, behavior regarding nurturing and ADHD symptoms respectively. Significant correlation was found between parental distress and warmth, rejection behavior. Parental distress is significant influence on behavior regarding nurturing through multiple regression analysis. Significant correlation was found between ADHD symptom and rejection behavior. ADHD symptom is significant influence on behavior regarding nurturing through multiple regression analysis. Behavior regarding nurturing is related to ADHD symptom, parental distress. Therefore, it is needed for not only treatment related to ADHD symptom but also interventions for behavior regarding nurturing for mothers of children with ADHD.

• Clean Technology
• /
• v.26 no.3
• /
• pp.211-220
• /
• 2020

This experimental study investigates the design parameters to achieve ultra low NOx combustion of coal using a 80 kW capacity single-burner furnace. The influence of key design parameters such as SN, overall and burner-zone equivalence ratios, primary/secondary air ratio, overfire air (OFA) ratio were tested for a total of 81 cases. The results showed that weak swirl intensity of the burner leads to higher NOx emission whereas strong swirl intensity accompanies increased CO concentration desipte lower NOx emission. Therefore, finding an appropirate swirl intensity is essential for the burner design. Larger flow rate of secondary air increased NOx emission, whereas smaller flow rate stretches the flame and increased CO emission. The lowest NOx emission of 82 ppm (6% O₂) was achieved at the optimal condition of the present burner deisgn. It is expected to furrther lower the NOx emission by introducing splitting the burner secondary air into three or four streams.

• Korean Journal of Cognitive Science
• /
• v.24 no.3
• /
• pp.203-235
• /
• 2013

The goal of this paper is to test the findings about English-speaking children's acquisition of inflectional morphemes in the literature using a large-scale database. For this, we obtained a 4.7-million-word corpus from the CHILDES (Child Language Data Exchange System) database, and analyzed 1,630 British and American children's uses of English derivational morphemes up to age 7. We analyzed the type and token frequencies, type per token ratio (TTR), and the lexical diversity (D) for such inflectional morphemes as the present progressive -ing, the past tense -(e)d, the comparative and superlative -er/est with reference to children's nationality and age groups. To sum up our findings, the correlations between the D value and children's age varied from morpheme to morpheme; e.g. we found no correlation for -ing, a marginal correlation for -ed, and a strong correlation for -er/-est. Our findings are consistent with Brown's (1973) classical observation that children learn progressive forms earlier than the past tense marker. In addition, overgeneralization errors were frequently found for -ed, but rarely for -ing, showing a U-shaped developmental pattern at ages 2-3. Finally, American children showed higher D scores than British children, which showed that American children used inflectional morphemes for more word types compared with British children. The present study has its significance in testing the earlier findings in the literature by setting up well-defined methodology for analyzing the entire CHILDES database.