Dynamic Analysis of the Effect of Network Externality in Vertically Differentiated Market Hyung-Rae Cho․Minho Rhee † Dept. of Industrial Systems Engineering/ERI, Gyeongsang National University

조형래(Hyung-Rae Cho):이민호(Minho Rhee) 한국산업경영시스템학회 2019 한국산업경영시스템학회지 Vol.42 No.2

Network externalities are essentially dynamic in that the value consumers feel about a product is affected by the size of the existing customer base that uses that product. However, existing studies on network externalities analyzed the effects of network externalities in a static way, not dynamic. In this study, unlike previous studies, the impact of network externalities on price competition in a vertically differentiated market is dynamically analyzed. To this end, a two-period duopoly game model was used to reflect the dynamic aspects of network externalities. Based on the game model, the Nash equilibria for price, sales volume, and revenue were derived and numerically analyzed. The results can be summarized as follows. First, if high-end product has strong market power, the high-end product vendor takes almost all benefits of the network externality. Second, when high-end product has strong market power, the low-end product will take over most of the initial sales volume increase. Third, when market power of high-end product is not strong, it can be seen that the effects of network externalities on the high and low-end products are generally proportional to the difference in quality. Lastly, if there exists a strong network externality, it is shown that the presence of low-end product can be more profitable for high-end product vendor. In other words, high-end product vendor has incentive to disclose some technologies for the market entrance of low-end product, even if it has exclusive rights to the technologies. In that case, however, it is shown that the difference in quality should be maintained significantly.

總輸膽管 結紮術후 Hepatic Glycogen 變化에 관한 形態學的 硏究

李亨周,李永浩,朴景蘭,金源式 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.1

For the study on the changes of hepatic glycogen after common bile duct ligation, Sprague -Dawley rats (b.w. 250± 20gm, male) were used as experimental animal. In expermental group, at 3hrs, 6hrs, 9hrs, 12hrs, 24hrs, 48hrs, 72hrs, 96hrs, and 120hrs after ligation, the common bile duct at the point of about 1cm proximal portion from its duodenal opening, the liver specimens were collected under ether anesthesia. Simple laparotomy was performed in control rats. After fixation, the specimens were sectioned 5㎛ thickness and stained with Periodic Acid Schiff, and observed under light microscope. Also, transmission electron microscopic photos were obtained with H-7000(Hitachi Co.) TEM. The results were as followings: 1. PAS reactions were changed into negative 6hours after common bile duct ligation. 2. Glycogen depletion after common bile duct ligation was closely related with functional lobule, but not in simple laparotomized rats. 3. In the common bile duct ligated rats, PAS negativity continued in the zone I until 120hours after ligation.

유방질환에 대한 방사선학적 연구

이병철,김형열 충남대학교 의과대학 지역사회의학연구소 1992 충남의대잡지 Vol.19 No.2

There are variable imaging modalities in detection and diagnosis of the breast disease, such as mammography, xeroradiography, ultrasonography, computed tomography, and magnetic resonsnce image. Among of them, mammography is most widely and easily used imaging modality, and have diagnostic values in screening and follow up study of the breast disease. The authors performed mammography in 249 patients with breast abnormalities who had visited to CNUH from Jan. 1992 to Nov., and we analyzed major symptoms of patients, mammographic findings, diagnostic accuracy in pathologically confirmed 113 cases, to know the usefulness of the mammography. 1. Age distribution of the patient is variable from 10th to 5th decade and the average is 38.9. 2. The most common complaint of the patient is palpable mass(59.4%) and the next is pain(22.1%). 3. The pathognomonic mammographic findings of the malignant breast disease is irregular marginated mass shadow with dystrophic calcification and occupies 26.5% of total cases, and the benign mass occupies 14.6%, and the other is fibrocystic disease(18.5%) which does not show the mass shadow. 4. Mmmographic findings was correlated with pathologic findings, and mammographic diagnosis was correct in 90.9% of carcinoma and 65.7% of benign disease. In conclusion, mammography is one of the most valuable imaging modalities which is not only widely and easily used but also provide the important information in screening and early detection of the breast disease.

열처리가 Elgiloy 선재의 기계적 성질에 미치는 영향

이병태,허택,최석규,김형일 대한치과교정학회 1992 대한치과교정학회지 Vol.22 No.3

Heat treatment which removes internal stress enhances the mechanical properties of the orthodontic arch wire. The main purpose of this experiment was to investigate the effects of the heat treatment on the mechanical properties of the Elgiloy wire. The Elgiloy wire, 0.016"X0.022" and 0.018"X0.025", were heat treated in an electric oven for 5, 10 and 15 minutes at selected temperatures between 300 and 900℃. Tensile strength and load deflection rate were measured to reveal the changes of mechanical property at various conditions, and each specimen was observed under metallurgic microscope. Also to trace the precipitation material due to overheat treatment, a qualitative analysis was carried out with EDS system. It was found that heat treatment at a low temperature caused an increase in the tensile strength and bending resistance, and a maintenance in the fibrous in the tensile strength and bending resistance, and a maintenance in the fibrous structure of both sizes of wire. The changes observed in properties and appearance were probably due to the relief of internal stresses incurred in the metal during cold working. In both sizes of wire the tensile strength and the bending resistance continued to decrease at high temperature, and the fibrous structure continued to disappear then was not observed at 900℃. The carbide precipitation founded in grain boundary at 750℃ probably was other elements carbide (Ni, Ca) except Cr. The grain growth was observed at 1100℃. Optimum heat treatment for the 0.016"X0.022" Elgiloy wire was 10 minutes at 500℃, and for the 0.018"X0.025: Elgiloy wire it was 5 to 15 minutes at 500℃.

합성펩타이드를 이용한 영양배엽세포-특이 가토 다클론 항혈청의 제작

이희섭,오재민,김정중,문형배,김원신,이황희 원광대학교 생명공학연구소 1995 생명공학연구소보 Vol.3 No.1

Within the last few years, a different approach to generating protein-reactive antibodies has been developed that has several advantages over conventional immunization. This involves synthesizing short peptide sequences, coupling them to immunogenic carrier molecules, and immunizing animals with the conjugates. 3βHSD(3β-hydroxy-5-ene steroid dehydrogenase; EC 1.1.1.145) is the enzyme of the plasma membrane of human trophoblast and it's cDNA sequence was identified by Nickon et al(Molecular cloning and expression of human trophoblast antigen FDO161G and its identification as 3β-hydroxy-5-ene steroid dehydrogenase. J Reprod Fert 1991;149;156). For the production of trophoblast-specific antibody, we synthesized three oligopeptides that are epitope sites chosen from cDNA sequence of 3βHSD. Oligopetides were coupled with KLH(keyhole limpet hemocyanin) under 25% glutaraldehyde. The trophoblast-specific rabbit polyclonal antisera was produced by conventional methods. This antisera reacts with a 43kDa protein in human placental lysate by Western blotting analysis and The syncytiotrophoblasts and cytotrophoblasts from villi are stained positively with this antisera by immunohistochemistry. Villous trophoblasts were cultured in methionine-free media for 1 hour and [^(35)S]-Methionine for 24 hours. Media and cell lysate were immunoprecipitated with this antisera and 12% SDS-PAGE was performed. In fluorography, bend was not noted in media and 43kDa band was noted in medis and 43kDa band was noted in lysate. It was concluded that anti-3βHSD antibody produced by synthetic peptide was specific to trophoblasts and 3βHSD was membrane-bound protein of trophoblasts.

韓國産 植物凝集素 Celosia argentea L.의 凝集活性에 關한 硏究

李亨柱,文國鎭 고려대학교 의과대학 1981 고려대 의대 잡지 Vol.18 No.1

Extracts of ground seeds of the Korean Celosia argentea L. were prepared in the usual manner and agglutination with human red blood cells, agglutination titration, agglutination inhibition with human saliva and various sugar solutions, absorption with human red blood cells and agglutination with ficinated red blood cells were carried out. And demonstrated that the certain red blood cells were markedly agglutinated by Celasia extracts, while it was failed to agglutinate other red blood cells. Since such differences in reactivity were observed also among red cells of groups O, it was apparent that new blood factor being detected by the Celosia extracts, therefore, designated anti-Cea lectin Celosia, and the red cells which gace marked agglutination with anti-Cea lectin were Cea(+) type and failed to agglutinate were Cea(-) type. In the first wcperiment on a series of 732 blood specimens(310 of male donors, 173 of male trauma cases, 171 of puerperants and 78 of female trauma cases) observed that the frequency of Cea(+) type was 98% and Cea(-) type was 2%, and there were no differences in the distribution of Cea(+) and Cea(-) frequencies between male and female, and among ABO blood groups. In the second experiment on a series of 1,192 blood specimens of various pathological conditions observed that a high frequency of Cea(-) type was noted in red blood cells of the patients with gastric ulcer (13%, Z score=2.2064), duodenal ulcer(17%, Z score=3.4340) and stomach cancer (19%, Z score=2.7654). No appreciable differences were noted in the blood specimens of the patients with gastritis, enterocolitis, appendicitis, pancreatitis, hepatitis, liver cirrhosis, cholecystitis, cholelithiasis, bronchitis, bronchial asthma, pneumonia, pulmonary tuberculosis, diabetes, hypertension, leukemia, nephritis, typhoid fever and malignancy (without stomach cancer).

대퇴골 경부 골절에 대한 임상적 고찰

민형식,이광진 충남대학교 의과대학 지역사회의학연구소 1986 충남의대잡지 Vol.13 No.1

27 cases of femoral neck fractures which were treated in department of orthopaedic surgery of CNUH from 1979 Jan. to 1985 Jan, were analysed clinically and radiologically. Very sensitive, noninvasive, simple and easily reproducible bone scanning with 99m Tc was introduced fro early diagnosis of avascular necrosis as a complication of femoral neck fracture. The results were as follows: 1. The most common cause of fracture was slipping and falling down. 2. In classification, transcervical and subcapital fractures were most common in anatomical classification, Pauwels' type I in Pauwels' classification and Garden stage 3 in displacement. 3. Singh index was decreased according to increase of physiological age. 4. Avascular necrosis develops commonly in Pawels' type 3, Garden's stage 4 and subcapital fracture. 5. Satisfactory results were obtained 75% in internal fixation and 85% in head replacement. 6. Bone scan is considered to be significant technique for early detection of vascular impairment to the femoral head after femur neck fracture, and is important in selecting the method of treatment according to results of bone scan.

t-분포를 이용한 의사-전체검사에 관한 연구

조형철,이정현,이강현 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.1

This paper deals with the path sensitization algorithm from PI to PO center on the nodes of high testability mainstay when CUT is tested by pseudo-exhaustive testing. Focusing on the defined nodes of high testability mainstay, we performed the singular cover and consistency operation to the forward and backward logic gates. Thus, we easily generated the pseudo-exhaustive test patterns. As a result, (1-α) region has 0.1579 and the pseudo-exhaustive test patterns are least generated and the rate of test pattern is 1.22%, compared with exhaustive testing. (1-α region has 0.2368 and this result exhibits the optimal performance of the singular cover and consistency operation. Applying the generated pseudo-exhaustive test patterns to the stuck at faults existing on the inputs and internal nodes in CUT, we verified this performance on the output. Thus, it is confirmed that fuctional testing of the proposed path sensitization algorithm is very useful.

부신적출이 조직 Li분포에 미치는 영향

김형근,성호경,이상돈 중앙대학교 의과대학 의과학연구소 1975 中央醫大誌 Vol.1 No.1

Effect of adrenalectomy on lithium distribution in various tissues of rats was studied. Rats were divided into three groups; namely, untreated, Li treated, and Li treated after adrenalectomy was done on 3rd dat prior to lithium treatment. Animals were killed following lithium treatment, and tissues including blood were taken immediately and digested and Li and Na concentrations were measured by atomic absorption spectroscopy. Effect of adrenalectomy on lithium distribution in various tissues was abserved, e. g. : brain skeletal muscle, bone, liver, renal cortex, cardiac muscle as well as plasma and erythrocyte. Correlations of Li concentrations were analyzed for each tissues. Results were smmarized as follows: 1. Adrenalectomy resulted an increase of lithium concentrations of various tissues in rats. 2. Erythrocyte to plasma ratio of lithium concentration was elevated in adrenalectomized rats, and it was considered that Li passed fairly well into cell under the adrenalectomy. 3. Adrenalectomy promoted the lithium retention in some tissues, especially bone, skeletal muscle and brain. 4. No correlation between tissues Li and Na was observed every tissues examined. 5. Lithium retention mechanism and pattern of distribution in some tissues of adrenalectomized rats were discussed.

多汗證에 대한 韓醫學的 考察

鄭熙才,鄭昇杞,李珩九 경희대학교 1997 慶熙醫學 Vol.13 No.4