• Journal of Oral Medicine and Pain
• /
• v.22 no.2
• /
• pp.295-307
• /
• 1997

This study was performed to investigate the reproductibility of eccentric mandibular movements according to preferred chewing side, range of mouth opening, type of lateral guidance and involvement of temporomandibular disorders. 50 patients with temporomandibular disorders and 65 dental students without any signs and symptoms were randomly selected for this study as the patients group and the control group, respectively. For recording and observation of eccentric mandibular movement trajectory, BioEGN$^\textregistered$ of Biopak$^\textregistered$ system (Bioresearch Inc., USA) was used. Each eccentric movement to anterior, right and left side was performed three times similar to the movement pattern for Pantronic Reproducibility Index. mandibular path was analyzed by three dimensional positional change and the three paths from one direction were compared with one another. From this, reproducibility index of one-directional lateral movement could be calculated, and total reproducibility index, named BioEGN reproducibility index(BERI), was also computed from three-directional eccentric movement likewise. BioEGN reproducibility Index could have four value of score by small or large scale, and by outgoing or incoming movement. The data were analyzed by SAS/stat program and the results obtained were as follows: 1. Right side chewing subjects showed more consistent pattern In reproducibility index in comparison between patients group and control group than left chewing subjects have done, and reproducibility was low in patients group. However, there was no difference between the two stoups in bilateral chewing subjects. 2. There were no difference in reproducibility index between preferred chewing side and contralateral side in unilateral chewing subjects whereas reproducibility index in left side on outgoing movement were higher than in right side in bilateral chewing subjects. 3. Difference in total reproducibility index(BERI) between canine guidance group and non-canine guidance group were not observed though difference in reproducibility index on lateral movement were observed in part. 4. There were no difference in reproducibility index between affected side and contralateral side in unilaterally affected patients, and between unilaterally affected patients and bilaterally affected patients in patients group. 5. Highly significant positive correlationship were shown among the four 쇼pes of total reproducibility index(BERI) in total subjects, and range of clinical mouth opening was negatively correlated with BEBI on outgoing movements and with index on outgoing movement to preferred side.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.6
• /
• pp.569-575
• /
• 1984

The characteristics of the stress corrosion cracking of SUS 304 stainless steel weldments were studied with the speciments of the constant displacement type under the environment of 42% MgC $l_{2}$ boiled solution (143.+.-.2.deg.C). The susceptibility of initiation and propagation of the stress corrosion crack was quantitatively inspected in the weld metal, heat affected zone and heat affected zone with including the reinforcement shape, respectively. Also, those susceptibility were discussed in connection with the change of mechanical and microstructural characteristics caused by heating cycle of welding. Main results obtained are as follows: (1)Stress corrosion cracking is easiest to initiate and propagate in the heat affected zone of weldment. (2)The susceptibility of stress corrosion cracking of the weldment is largely improved by eliminating the reinforcement part of the weld bead. (3)The dominant factor of the cracking susceptibility of the heat affected zone appeared to be the phenomenon of softening and sensitizing caused by welding heat cycle. (4)Under the low loading conditions, the behavior of stress corrosion cracking of the SUS 304 steel weldment is largely influenced by the pitting phenomenon in the front region of the main crack.

• Korean Journal of Child Studies
• /
• v.32 no.6
• /
• pp.123-139
• /
• 2011

This study sought to examine the impact of reading ability and vocabulary at age 5, as well as analyzing the impact which children's gender, parental education level and family income level has on reading comprehension ability and vocabulary at the first grade level in primary school. The study also sought to compare the characteristics of the results obtained in Korea and Japan on this particular research topic. For the Korean part of the study, 328 first grade Korean children, who had participated in the initial testing as five-year olds and agreed to participate in the longitudinal study were tested; whereas in Japan, 215 students were tested. The study results indicated that, in the case of Korea, reading comprehension ability in the first grade was affected by vocabulary and reading abilities at age 5, gender, as well as the mother's education level, in that order. In Japan, it was affected in the order of vocabulary, gender, and father's education level. In terms of first grade vocabulary, in the case of Korea, it was affected in the order of vocabulary and reading ability at age 5 and father's education level; whereas in Japan, it was affected in the order of vocabulary, gender, and reading ability. In both Korea and Japan, at age 5, vocabulary was shown to have a more significant impact than reading ability on both of language ability and vocabulary in the subsequent primary school period. As such, it can be seen that more interest should be shown not only in the ability to read at age 5 but also in expanding the vocabulary of children at this age through appropriate interaction and support.

• Journal of the Korea Safety Management & Science
• /
• v.11 no.4
• /
• pp.57-67
• /
• 2009

The psychosocial stress and musculoskeletal disorders(MSDs) have been one of major health problems for hospital workers. This study tried to understand the relationship between symptoms associated with MSDs and risk factors such as working posture, job stress, psychosocial stress and fatigue. A total number of 655 hospital workers participated in this study. Specifically, REBA was applied for evaluating working posture and a checklist prepared by KOSHA(Korean Occupational Safety and Health Agency) was used for symptom survey. A questionnaire from KOSHA was also used for collecting data associated with job stress, psychosocial stress and fatigue. All these data were formulated and modeled by path analysis which was one of major statistical tools in this study. Specifically, path analysis for the data we collected came up with several major findings. As a result, as for body part(neck), (waist) and (arms) the degree of risk of work posture measured with the use of job stress(KOSS), psycho-social stress(PWI-SF) and REBA is significantly more affected by fatigue than muscular skeletal disease related consciousness symptom. However, regarding bod(wrist), the degree of risk of work posture measured with the use of job stress(KOSS) and REBA is directly affected by muscular skeletal disease related consciousness symptom. This study is meaningful in that the study clarified the causal relations of the degree of risk of work posture, degree of fatigue, and muscular skeletal disease related consciousness symptoms by each body part measured with the use of work stress(KOSS), psycho-social stress(PWI-SF) and REBA.

• Journal of Mechanical Science and Technology
• /
• v.16 no.12
• /
• pp.1693-1701
• /
• 2002

The intermittent spray characteristics of a multi-hole and a single-hole diesel nozzle were experimentally investigated. The hole number of the multi-hole nozzle was 5, and the hole diameter of the 5-hole and the single-hole nozzle was the same as d$\_$n/=0.32 ㎜ with the constant hole length to diameter ratio(l$\_$n//d$\_$n/=2.81). The droplet diameters of the spray, including the time-resolved droplet diameter, SMD (Sauter mean diameter) and AMD (arithmetic mean diameter) , injected intermittently from the two nozzles into the still ambient were measured by using a 2-D PDPA (phase Doppler particle analyzer). Through the time-resolved evolutions of the droplet diameter, it was found that the structure of the multi-hole and the single-hole nozzle spray consisted of the three main parts : (a) the leading edge affected by surrounding air. and composed of small droplets; (b) the central part surrounded by the leading edge and mixing flow region and scarcely affected by the resistance of air, (c) the trailing edge formed by the passage of the central part. The SMD decreases gradually with the increase in the radial distance, and the constant value is obtained at the outer region of the radial distance (normalized by hole diameter) of 7-8 and 6 for the 5-hole and single-hole nozzle, respectively. The SMD along the centerline of the spray decrease shapely with the increase in the axial distance after showing the maximum value near the nozzle tip. The SMD remains the constant value near the axial distance(normalized by hole diameter) of 150 and 180 for the 5-hole and the single-hole nozzle, respectively.

• Journal of environmental and Sanitary engineering
• /
• v.5 no.1
• /
• pp.1.2-6
• /
• 1990

The purpose of this experiment was to investigate boron deficient symptom of sugar beet. Sugar beet affected by boron deficiency was anatomized and observed by microscope and electron microscope. The sugar beet plants affected onboron deficiencyu with water culture and those of the experimental farm alike contained a small amount of boron. The symptom of boron deficiency began to show dark-brown lines at the ventral suface of the basal part of petiole and then, in the ridge of young leaf, growing point became darkened due to necrosis. The leaf blade was wrinked severely and finally the growth was stunted. The boron deficiency began with necrosis of the epidermis of the ventral surface of the basal part of petiole, and parenchyma under it. Necrosis and disintegration of the ridge of young leaf began to take place and were expanded gradually. Electron microscopic examination of boron deficient sugar beet plants revealed that chloroplasts degenerated, and appeared to contain larger amounts of starch, also observed larger number of osmophilic granules. And they peculiarly were found polyhedral crystals in the certain deficient chloroplasts.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.7
• /
• pp.252-257
• /
• 2018

In this paper, we propose a mean time to failure (MTTF) to improve the solution for a cryogenic cooler, which is an important part of a cooled thermal device. Common electronic devices have a high possibility of failure due to various environmental factors, such as temperature and humidity. But some special devices (such as thermal devices) are designed to overcome environmental factors. The most affected part of a cooled thermal device's MTTF is the cryogenic cooler. The MTTF of a cryogenic cooler is affected by the device's internal heat. Therefore, if the device's internal heat is reduced, the cryogenic cooler's MTTF increases. From the present device's internal heat simulation, we analyze the improvement method of the device. The proposed improvement method's effectiveness is verified by simulation and MTTF calculation.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.37 no.3
• /
• pp.36-42
• /
• 2014

Domestic 105mm HE (High Explosive) shell is composed of three parts that are Fuze, Projectile and Propellants. Among three parts, propelling charge of propellants part consists of single base propellants. It has been known that the lifespan of single base propellants is affected by a storage period. These are because Nitrocellulose (NC) which is the main component of propelling gunpowder can be naturally decomposed to unstable substances similar with other nitric acid ester. Even though it cannot be prevented fundamentally from being disassembled, a decomposition product ($NO_2$, $NO_3$, and $HNO_3$) and tranquillizer DPA (Diphenylamine) having high reactivity are added into a propellant to restrain induction of automatic catalysis by a decomposition product. The decay rate of the tranquillizer is also affected by a production rate of the decomposition product of NC. Therefore, an accurate prediction of the Self-Life is required to ensure against risks such as explosion. Hereupon, this paper presents a new methodology to estimate the shelf-life of single base propellants using data of ASRP (Ammunition Stockpile Reliability Program) to domestic 105mm HE (propelling charge of propellants part). We selected four attributes that are inferred to have influence on distribution of the DPA amount in a propellant from the ASRP dataset through data mining processes. Then the selected attributes were used as independent variables in a regression analysis in order to estimate the shelf-life of single base propellants.

• Journal of the Korean Society of Costume
• /
• v.57 no.4 s.113
• /
• pp.143-158
• /
• 2007

This study considers enlargement phenomenon in hair style as one of Costume types and analyzes its artistic characteristics based on the comparison between Hair style in the late Chosun Dynasty and that of the Rococo. First, its formative property, one of the common aesthetic characteristics, breaks the concept of traditional balance in Clothing and emphasizes its transformation, changes, and space beauty. This formative property shows the Enlargement and exaggeration beyond the concept of Space. Its sensuous property reflects women's psychological minds; exaggeration and sensualism. Artistic property doesn't focus on hair style only or clothing style only and considers hair style as renter of beauty as well as its important element. It shows the traditional beauty of nature and creativity in the Chosun Dynasty. Second, its formative property, one of the differential aesthetic characteristics, shows these following differences considering the aesthetic characteristics in the late Chosun Dynasty and that of the Rococo; mutual transformation, independent transformation, focus on distortion, harmony in scale, disharmony between irregularity and exception, extension and separation in space, etc. Sensuous property shows the temperate beauty and metaphorical sense, affected by the Practical Science, in the late Chosun Dynasty while it shows the secular sense and exaggerated beauty, affected by the Enlightenment, in the Rococo. Artistic property shows the harmony with the Clothing style, balanced wearing lines, and natural beauty, as one part of Clothing, in the late Chosun Dynasty. However it shows creativity, as separate part from Clothing, in the Rococo.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.2
• /
• pp.666-671
• /
• 2016

This paper introduces a device providing close local lighting to the affected part, where the operation-purpose astral lamp alone cannot shed light directly, in an operation room of hospitals or clinics, which helps clinical doctors perform safe treatment of the affected part deep inside a human body. This medical assisting lighting is a device necessary to prevent fatal operation failures, which can occur with minute operation processes, such as tumor removal or angiorrhaphy. The components, such as the light source and power supply were designed to be low power consuming and small in size, have a narrow angle lens was used to increase the light spreading effect and focused illumination. The end-caps of the light transmission device using an optical cable and the lighting device were designed in the waterproof type to enable disinfection of these devices after use for the next patients. According to the measurement of the light source properties made after development of the retractor lighting device, the illumination intensity was 490 lux, the brightness was $11,550cd/m^2$, general color rendering index was 78, color temperature was 11,000K, and the intensity distribution was even, which were confirmed to be adequate for medical assisting local lighting.