• Journal of Korean Academy of Nursing
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• v.41 no.3
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• pp.364-373
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• 2011

Purpose: In this study the fitness of a path model for the relationship among biological risk disposition, sociocultural risk factors, self-control, parent-adolescent communication, and risk behavior in adolescents was examined. Methods: The participants were 387 adolescents. The data were analyzed with the PASW 18.0 and AMOS 18.0 programs. Results: Sociocultural risk factors, self-control, and parent-adolescent communication showed a direct effect on risk behavior for adolescents, while biological risk disposition and sociocultural risk factor showed an indirect effect on risk behavior for adolescents. The modified path model of adolescents' risk behavior was showed a good fit with the model ($X^2$/df=2.37, GFI=.95, AGFI=.92, RMSEA=.06 [.05

• Journal of the Korean society of biological therapies in psychiatry
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• v.24 no.3
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• pp.129-141
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• 2018

Suicide is a behavior that is intended to cause death by itself and requires medical treatment, resulting in suicidal attempt or completion. Suicide causes loss of life, damages the body, costs a lot of medical expenses, and causes families to fall into sorrow and suffering therefore this suicide is a huge loss to family and society. There have been attempts to reduce and prevent suicide by understanding the mechanism of suicide. The mechanism of suicide can be thought of as psychological mechanism and biological mechanism. In the past, if we considered the psychological and biological mechanisms separately, the development of neuroscience now connects and integrates these two. Psychological factors affect biological factors and biological temperaments also affect perception or thinking about the situation and increase psychological vulnerability. Distant factors in suicidal behavior-such as childhood adversity and family and genetic predisposition-increase the lifetime risk of suicide. They alter the response to stress and other processes through changes in gene expression and regulation of emotional and behavioral characteristics. Distant factors affect the biological system and consequently changes in these systems can increase the risk of suicide. In other words, the distal factor does not directly induce suicidal behavior but rather acts indirectly through developmental or mediating factors. These mediating factors are impulsive aggressive and anxious trait, and chronic use of substances. The mechanism of this disorder is the abnormality of the serotonin system and the abnormality of the lipid level. Proximal factors are associated with the onset of suicide events and include changes in the major neurotransmitter systems, inflammatory changes, and dysfunction of glial cells in the brain. A series of studies, including a variety of research methods and postmortem and in-vivo imaging studies, show the impairment of the serotonergic neurotransmitter system and hypothalamic-pituitary-adrenal axis stress response system for suicidal behavior. These disorders lead to suicidal behavior due to difficulty in cognitive control of mood, pessimism, reactive aggression, abnormality in problem solving abilities, excessive response to negative social signals, severe emotional distress, and cognitive dysregulation of suicidal ideation.

• Journal of Preventive Medicine and Public Health
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• v.53 no.6
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• pp.419-428
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• 2020

Objectives: Adolescent suicide is a global problem. This study aimed to identify associations between parental marital status and suicidal behavior. Methods: This study analyzed 118 715 middle and high school students from the 13th and 14th Korea Youth Risk Behavior Web-based Survey. The odds ratios (ORs) of suicidal ideation, planning, and attempts were calculated based on parental marital status, living situation, and socioeconomic factors. The data were analyzed using multiple logistic regression. Results: When compared to those living with 2 married biological parents, the ORs of suicidal ideation among adolescents living with either remarried or no parents were 1.34 (95% confidence interval [CI], 1.17 to 1.53) and 1.36 (95% CI, 1.11 to 1.66), respectively. For suicidal planning, the OR of those living with 1 remarried biological parent was 1.24 (95% CI, 1.01 to 1.52), and that of those living without parents was 1.28 (95% CI, 0.95 to 1.73), when compared to adolescents living with 2 married biological parents. For suicide attempts, when compared to adolescents with 2 married biological parents, the OR of those living with 1 remarried biological parent was 1.48 (95% CI, 1.17 to 1.87) and that of those living without parents was 2.02 (95% CI, 1.44 to 2.83). For adolescents living with 1 remarried biological parent, suicidal behavior was strongly associated with having no siblings and were weakly associated with not living with grandparents. Conclusions: Suicidal behavior among adolescents was associated with the remarriage and loss of parents. Therefore, special attention and interventions are needed for adolescents in those situations.

• Korean Journal of Biological Psychiatry
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• v.12 no.1
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• pp.3-12
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• 2005

Most suicides(about 90%) occur in the context of psychiatric disorders. Prediction of suicide risk in patients with mental illness is very important in preventing suicide attempts. However, current approaches to predict suicidality are based on clinical history and have low specificity and biological markers are not yet included. Many studies have explored the association between different biological parameters and suicidality. Studies of cerebro-spinal fluid(CSF) demonstrated that 5-HIAA and HVA levels were lower in patients with a history of suicide. Platelet serotonin transporter and the 5-HT2 serotonin receptor have also been studied in relation to violence and suicide. Depressive patients with greater suicidal tendency had significantly lower cholesterol concentrations but some researchers failed to find the correlation. DST non-supression is reported to predict suicidality in major depression. Several studies demonstrated a relationship between intron 7 polymorphism of tryptophan hydroxylase and suicidal behavior. Since suicide is not occurred in a single disease, the systematic and comprehensive study in large samples with various diagnoses is necessary to find the biological and genetic predictors of suicidal behavior.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.222-229
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• 2000

In this paper we will assess the feasibility of some insect behavior-modifying chemicals for insect control, such as male orientation inhibitor, female calling interrupter and female attractant of cotton bollworm Helicoverpa armigera. These behavior-modifying chemicals have advantages of simple chemical structure, easy to synthesize and low price of products. The effects of sub-lethal insecticides on insect chemical communication system and the differences of pheromone communication systems between the resistant and susceptible strain of H. armigera will also be discussed.

• Molecules and Cells
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• v.40 no.3
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• pp.186-194
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• 2017

A brain-enriched secreting signal peptide, NELL2, has been suggested to play multiple roles in the development, survival, and activity of neurons in mammal. We investigated here a possible involvement of central NELL2 in regulating feeding behavior and metabolism. In situ hybridization and an immunohistochemical approach were used to determine expression of NELL2 as well as its colocalization with proopiomelanocortin (POMC) and neuropeptide Y (NPY) in the rat hypothalamus. To investigate the effect of NELL2 on feeding behavior, 2 nmole of antisense NELL2 oligodeoxynucleotide was administered into the lateral ventricle of adult male rat brains for 6 consecutive days, and changes in daily body weight, food, and water intake were monitored. Metabolic state-dependent NELL2 expression in the hypothalamus was tested in vivo using a fasting model. NELL2 was noticeably expressed in the hypothalamic nuclei controlling feeding behavior. Furthermore, all arcuatic POMC and NPY positive neurons produced NELL2. The NELL2 gene expression in the hypothalamus was up-regulated by fasting. However, NELL2 did not affect POMC and NPY gene expression in the hypothalamus. A blockade of NELL2 production in the hypothalamus led to a reduction in daily food intake, followed by a loss in body weight without a change in daily water intake in normal diet condition. NELL2 did not affect short-term hunger dependent appetite behavior. Our data suggests that hypothalamic NELL2 is associated with appetite behavior, and thus central NELL2 could be a new therapeutic target for obesity.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.233-241
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• 1996

The mechanical properties of biological materials depend on numerous factors. The majority of these relationships are still unknown today, especially with regard to their quantitative characteristics. The reason is that biological materials constitute biomechanical systems of very complex construction, whose behavior cannot be characterized by simple physical constants, as for example can that of engineering materials. The objectives of this investigation were to determine the compression creep and recovery properties of rice stalks at various levels of applied load The compression creep and recovery behavior of the rice stalk could be predicted precisely by rheological model which approached closely to the measured values. But the coefficients of the Burgers recovery model were different from those of the creep model. The Steady state creep behavior occurred at the higher level of force and the logarithmic creep behavior occurred at the lower level of force. The mechanical model being expected the creep behavior in relation with the level of applied load, which was well explained that the rice stalk might be visco-elastic material.

• Korea-Australia Rheology Journal
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• v.15 no.3
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• pp.151-156
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• 2003

In this research, experimental studies were performed to examine the rheological behavior of equimolar solutions of cetylpyridinium chloride (CPyCl) and sodium salicylate (NaSal) solutions with concentration. The surfactant solutions were prepared by dissolving 2 mM/2 mM - 80 mM/80 mM of surfactant/counterion in double-distilled water. It has been observed that the zero shear viscosity shows abrupt changes at two critical values of C^*$ and C^{**}$. These changes are caused by the switching of relaxation mechanism with concentration of CPyCl/NaSal solutions at those concentrations. The wall slip velocities of dilute and semidilute CPyCl/NaSal solutions show a dramatic increase with shear rate where the shear viscosity exhibits shear thickening behavior for dilute solutions and shear thinning behavior for semi-dilute solutions, respectively. Considering that the dramatic increase in wall slip velocity should be related to the formation of shear-induced structure (SIS) in the surfactant solution, the shear thickening behavior of semi-dilute solutions is caused by elastic instability unlike the case of dilute solutions.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.3
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• pp.284-291
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• 2011

Numerical experiments on biological interfacial layer, DEJ by finite element software ABAQUS have been conducted to study its fracture behavior including crack bridging / arresting characteristics in the model. Crack growth simulation has been carried out by numerical tool, XFEM, devoted to study cracks and discontinuities. The fracture toughness of DEJ has been estimated before and after crack bridging. The implications of bridging in numerical study of fracture behavior of DEJ-like biological interface have been discussed. It has been observed that the results provided by the numerical studies without proper accommodation of bridging phenomenon can mislead. This study can be helpful for understanding the DEJ-like biological interface in terms of its fracture toughness, an important material characteristics. This property of the material is an important measure that has to be taken care during design and manufacturing processes.

• Journal of Ecology and Environment
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• v.29 no.1
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• pp.49-53
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• 2006

The fiddler crab, Uca lactea, which lives on intertidal mudflats in Korea, exhibits both burrow mating and surface mating. We observed 17 cases of surface mating that occurred on Ganghwa Island, South Korea. Most surface-mating males did not build semidomes, structures that attract searching females for burrow mating. Based on the conclusion of a previous study that semidome building is condition-dependent, we suggest that food availability may influence the mating tactic of this species. In addition, there was a strong correlation between the carapace size of both sexes that surface-mated, which suggests that males use body size of females as a mating cue.