• Journal of Powder Materials
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• v.19 no.2
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• pp.117-121
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• 2012

Tool steels serve a large range of applications including hot and cold workings of metals and injection mouldings of plastics or light alloys. The high speed steels (HSS) are specifically used as cutting tools and wear parts because it has high strength, wear resistance and hardness along with appreciable toughness and fatigue resistance. From the view of HSS microstructure, it can be described as metallic matrix composites formed by a ferrous with a dispersion of hard and wear resistant carbides. The experimental specimens were manufactured using the PIM with T42 powders (50~80 vol.%) and polymer (20~50 vol.%). The green parts were debinded in n-hexane solution at $60^{\circ}C$ for 8 hours and thermal debinded at an $N_2-H_2$ mixed gas atmosphere for 8 hours. Specimens were sintered in high vacuum ($10^{-5}$ Torr) and various temperatures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.537-544
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• 2011

This work was conducted to investigate the oxidation characteristics of methane having the highest ignition temperature among the other hydrocarbon gases using transition metal catalysts. The catalyst used for methane oxidation was manganese oxide having a various oxidation number, such as MnO, $MnO_2$, $Mn_2O_3$, $Mn_3O_4$, $Mn_4O_5$. The manganese oxide(MnxOy) catalyst is impregnated on $TiO_2$, $Al_2O_3$ for methane oxidation. To enhanced both of activity and life time of catalysts, Ni and Co was used as a promoter. In this study, various co-catalysts were synthesized by using excess wet impregnation method. The effect of reaction temperature and space velocity was measured to calculate the activity of catalysts such as, activation energy of $T_{50}$, and $T_{90}$. The life time of bi-metallic manganese mixture, such as Mn-Co and Mn-Ni catalysts, were increased more 10 % than manganese oxide catalyst, but activity of those was decreased slightly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2029-2037
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• 2015

The purpose of this study was to investigate the effect the interferential current (IFC) stimulation level according to autonomic nerve system (ANS) of healthy adults. IFC measured with adhesive 2-pole electrodes pad on T1~T4 spinal cord segment level that electrode stimulation of 20 min after. A total of 45 healthy adults participated in the study, who were randomly divided into three groups: 15 of sensory level stimulus group (100 bps, 10~12 mA), 15 of exercise level stimulus group (5 bps, 45~50 mA), 15 of noxious level stimulus group (100 bps, 80~90 mA). Measured items were sympathetic activity and parasympathetic activity. In order to identify the changes in measurement variables before electrode stimulation and after and 30 min stimulation. The comparison of sympathetic and parasympathetic activity in each group revealed that they was changes of after vs 30 min in after electrical stimulation time(p<.05).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.3
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• pp.154-160
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• 1970

The present paper deals with the growth of yellow croaker by scale age reading. This study is based on material from 596 specimens caught by the Danish seine in the Yellow Sea during the period from June 1967 to April 1968. Ring marks of the scale were formed from April to July, corresponding to the spawning season of the fish reported by Bae (1960). Growth rate of each radius of the ring was approximately 0.73. The relationship between the total length and radius of scales, and the relationship between the body weight and total length are represented by the following equations respectively: L=61.350R+50.184 $$W=4.298L^{3.227}\times10^{-3}$$ Maximum total length calculated by the diagram of Walford's growth transformation, $$L_{n+1}=0.6866L_n+10.8730$$, was 346.9mm. Growth curve of the fish can be expressed by the following von Bertalanffy's equation : $$L_t=346.9(1-e^{-0.376(t+0.609)})$$

• Journal of the Korean Society of Tobacco Science
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• v.2 no.1
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• pp.8-16
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• 1980

The cavity of triple filter was filled with the mixture of clinoptilolite and charcoal(1:1, V/V). The particle size of clinoptilolite was 30$\pm$5 A.S.T.M mesh. The reduction effects of the important gaseous components by this mixture were obtained as follows: 1) In comparison with the normal cellulose acetate niter, the contents of nicotine and T.P.M. were reduced about 35% and 22% respectively. 2) Many aliphatic and cyclic compounds were also substantially reduced in an average of 60%. 3) In contrast with the charcoal, the removal efficiency of clinoptilolite was revealed as higher (15-20%) in case of aliphatic compounds than the one (10-15%) of cyclic compounds. The above results showed us that the removal function of gaseous components was quite complementary each other (charcoal and clinoptilolite).

• Food Science and Preservation
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• v.10 no.1
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• pp.94-98
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• 2003

Effect of mixture of food material water extracts(modouri) composed of Job's tears, maize, buckwheat Japanese mushroom, lovage, licorice and jujube(13 : 50 : 15 : 2 : 5 : 5 : 5, v/v)] on the content of testosterone(T) and dihydrotestosterone(DHT), biochemical and histological changes of rat were investigated. Animal experiments(30 rats) were divided into 3 experimental groups(control, modouri and propecia). The summarized results were as follows: Activities of GOT, GPT, ALP, ${\gamma}$-GTP and content of total cholesterol and total lipid are normal in modouri group. Therefore modouri does not give rise to any damage in the liver. Also in the histological view, modouri does not have any hepatotoxic effect and increase the number of hair folicle. Total(T+DHT) and DHT content in rat serum and skin are significantly decrease in modouri group compare to the control but there is not any significant difference with propecia.

• Journal of Korean Neurosurgical Society
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• v.50 no.4
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• pp.392-395
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• 2011

Idiopathic hypertrophic spinal pachymeningitis (IHSP) is a rare inflammatory disease characterized by hypertrophic inflammation of the dura mater and various clinical courses that are from myelopathy. Although many associated diseases have been suggested, the etiology of IHSP is not well understood. The ideal treatment is controversial. In the first case, a 55-year-old woman presented back pain, progressive paraparesis, both leg numbness, and voiding difficulty. Initial magnetic resonance imaging (MRI) demonstrated an anterior epidural mass lesion involving from C6 to mid-thoracic spine area with low signal intensity on T1 and T2 weighted images. We performed decompressive laminectomy and lesional biopsy. After operation, she was subsequently treated with steroid and could walk unaided. In the second case, a 45-year-old woman presented with fever and quadriplegia after a spine fusion operation due to lumbar spinal stenosis and degenerative herniated lumbar disc. Initial MRI showed anterior and posterior epidural mass lesion from foramen magnum to C4 level. She underwent decompressive laminectomy and durotomy followed by steroid therapy. However, her conditions deteriorated gradually and medical complications occurred. In our cases, etiology was not found despite through investigations. Initial MRI showed dural thickening with mixed signal intensity on T1- and T2-weighted images. Pathologic examination revealed chronic nonspecific inflammation in both patients. Although one patient developed several complications, the other showed slow improvement of neurological symptoms with decompressive surgery and steroid therapy. In case of chronic compressive myelopathy due to the dural hypertrophic change, decompressive surgery such as laminectomy or laminoplasty may be helpful as well as postoperative steroid therapy.

• Korean Journal of Health Education and Promotion
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• v.2 no.1
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• pp.81-92
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• 1984

To find out the amount of knowledge and the attitude which a group of students attending local universities have toward family health, I distributed 690 questionaires to three local universities which I chose. I arrived at the following conculsion after 628 questionnairs were returned. 1) 431 male students(89.8%) and 126 femals students (86.2%) felt that family health science is important enough to be part of the cirriculum. 2) 374 male students (74.5) and 132 female students (90.4%) answered that they get a basic knowledge of health and disease through massmedia. 3) Should an information bureau for health and diseare be retup, 369 students(63.2%) answered that they would join information bureau. 4) In regard to a basic knowledge of health, the report says that 419 ma1e students(83.4%) and 117 female students(80%) don't know about Blood pressure, and 422 male students(84%) and 124 female students (84.9%) don't know about normal pulse and 467 male students(93%) and 128 femal stdents(87.6%) don't know about normal respiration. 5) In regard to communicable disese, 186 male students(37.1%) and 61 female students(41.7%) have a basic knowledge of these disease. In regard to diseases which commonly afflict the eldrly, 157 male students (31.2%) and 62 female students (42.4%) have a basic knowledge of these diseases. In regard to other diseases, the finding of this report are that on the average male students(74.6%) and female students of(73.4%) don't have a basic knowledge of family health. 6) 182 male students (36.2%) and 50 female students (34.2%) anwered that the way to promote health and prevent disease is to have a medical examination regularly and also 142 male students (28.2%) and 33 female students(22.6%) answered that it is necessary to have knowledge about how to keep health. 7) 254 male students (50.4%) and 90 female students (61.6%) said that when they are sick they depend on help from the pharmacist.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.293-303
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• 2020

Objective: To investigate the three-dimensional (3D) surgical accuracy between virtually planned and actual surgical movements (SM) of the maxilla in two-jaw orthognathic surgery. Methods: The sample consisted of 15 skeletal Class III patients who underwent two-jaw orthognathic surgery performed by a single surgeon using a virtual surgical simulation (VSS) software. The 3D cone-beam computed tomography (CBCT) images were obtained before (T0) and after surgery (T1). After merging the dental cast image onto the T0 CBCT image, VSS was performed. SM were classified into midline correction (anterior and posterior), advancement, setback, anterior elongation, and impaction (total and posterior). The landmarks were the midpoint between the central incisors, the mesiobuccal cusp tip (MBCT) of both first molars, and the midpoint of the two MBCTs. The amount and direction of SM by VSS and actual surgery were measured using 3D coordinates of the landmarks. Discrepancies less than 1 mm between VSS and T1 landmarks indicated a precise outcome. The surgical achievement percentage (SAP, [amount of movement in actual surgery/amount of movement in VSS] × 100) (%) and precision percentage (PP, [number of patients with precise outcome/number of total patients] × 100) (%) were compared among SM types using Fisher's exact and Kruskal-Wallis tests. Results: Overall mean discrepancy between VSS and actual surgery, SAP, and PP were 0.13 mm, 89.9%, and 68.3%, respectively. There was no significant difference in the SAP and PP values among the seven SM types (all p > 0.05). Conclusions: VSS could be considered as an effective tool for increasing surgical accuracy.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.324-335
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• 2020

Objective: To compare postoperative positional changes in the mandibular proximal segment between the conventional orthognathic surgery (CS) and the surgery-first approach (SF) using intraoral vertical ramus osteotomy (IVRO) in patients with Class III malocclusion. Methods: Thirty-eight patients with skeletal Class III malocclusion who underwent bimaxillary surgery were divided into two groups according to the use of preoperative orthodontic treatment: CS group (n = 18) and SF group (n = 20). Skeletal changes in both groups were measured using computed tomography before (T0), 2 days after (T1), and 1 year after (T2) the surgery. Three-dimensional (3D) angular changes in the mandibular proximal segment, condylar position, and maxillomandibular landmarks were assessed. Results: The mean amounts of mandibular setback and maxillary posterior impaction were similar in both groups. At T2, the posterior portion of the mandible moved upward in both groups. In the SF group, the anterior portion of the mandible moved upward by a mean distance of 0.9 ± 1.0 mm, which was statistically significant (p < 0.001). There were significant between-group differences in occlusal changes (p < 0.001) as well as in overjet and overbite. However, there were no significant between-group differences in proximal segment variables. Conclusions: Despite postoperative occlusal changes, positional changes in the mandibular proximal segment and the position of the condyles were similar between CS and SF, which suggested that SF using IVRO achieved satisfactory postoperative stability. If active physiotherapy is conducted, the proximal segment can be adapted in the physiological position regardless of the occlusal changes.