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Fine Structure of Mature Sperms of Cephalopods (Octopus minor, Octopus ocellatus and Todarodes pacificus) Inhabiting the Korean Waters II (한국 연근해산 두족류 (Octopus minor, Octopus ocellatus and Todarodes pacificus) 성숙정자의 미세구조 II)

  • Kim, Sang-Won;Chang, Nam-Sub
    • Applied Microscopy
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    • v.31 no.4
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    • pp.333-345
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    • 2001
  • The mature sperms of three species of cephalopods (Octopus minar, Octopus ocellatus, Todarodes pacificus) were observed by electron microscopy. The results obtained are as follows: The sperm lengths of Octopus minor and Octopus ocellatus of octopods are long and they are about $390{\mu}m$ and $125\sim130{\mu}m$, respectively, but the sperm length of Todarodes pacificus is short and about $35{\mu}m$. The sperm of Octopus minor has a helical acrosome and a head bent a little like a banana while Octopus ocellatus of octopod has a twisted acrosome and a long rod-shaped head. A number of horizontal stripes are observed as a periodic structure in their subacrosome cavities and dense plugs are formed in the cavities of their heads. On the other hand, the acrosome of Todarodes pacificus is circular cap-shaped, and its head is long and oval. It is notable that two small cavities were observed in its basal acrosome. Juxtanuclear acrosomal materials of high electron density filled the subacrosomal cavity. In the middle piece of mature sperms of Octopus minor and Octopus ocellatus, the mitochondria form the mitochondrial sleeve, but the numbers of mitochondria differ between the species so that they are $11\sim12$ and $8\sim9$, respectively. Meanwhile, in the middle piece of mature sperms of Todarodes pacificus, the mitochondria are separated from the axoneme, forming a mitochondrial spur in which $10\sim13$ mitochondria and some electron dense materials concentrate. The axoneme of Octopus minor, Octopus ocellatus and Todarodes pacificus are of 9+2 type in common, surrounded by 9 coarse fibres. A number of glycogen were observed only in the axoneme of Todarodes pacificus. The coarse fibres were found as far as the main piece of sperm tail in Octopks minor and Todarodes pacificus, while to the end piece of sperm tail in Octopus ocellatus.

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Production of $[^{18}F]F_2$ Gas for Electrophilic Substitution Reaction (친전자성 치환반응을 위한 $[^{18}F]F_2$ Gas의 생산 연구)

  • Moon, Byung-Seok;Kim, Jae-Hong;Lee, Kyo-Chul;An, Gwang-Il;Cheon, Gi-Jeong;Chun, Kwon-Soo
    • Nuclear Medicine and Molecular Imaging
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    • v.40 no.4
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    • pp.228-232
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    • 2006
  • Purpose: electrophilic $^{18}F(T_{1/2}=110\;min)$ radionuclide in the form of $[^{18}F]F_2$ gas is of great significance for labeling radiopharmaceuticals for positron omission tomography (PET). However, its production In high yield and with high specific radioactivity is still a challenge to overcome several problems on targetry. The aim of the present study was to develop a method suitable for the routine production of $[^{18}F]F_2$ for the electrophilic substitution reaction. Materials and Methods: The target was designed water-cooled aluminum target chamber system with a conical bore shape. Production of the elemental fluorine was carried out via the $^{18}O(p,n)^{18}F$ reaction using a two-step irradiation protocol. In the first irradiation, the target filled with highly enriched $^{18}O_2$ was irradiated with protons for $^{18}F$ production, which were adsorbed on the inner surface of target body. In the second irradiation, the mixed gas ($1%[^{19}F]F_2/Ar$) was leaded into the target chamber, fellowing a short irradiation of proton for isotopic exchange between the carrier-fluorine and the radiofluorine absorbed in the target chamber. Optimization of production was performed as the function of irradiation time, the beam current and $^{18}O_2$ loading pressure. Results: Production runs was performed under the following optimum conditions: The 1st irradiation for the nuclear reaction (15.0 bar of 97% enriched $^{18}O_2$, 13.2 MeV protons, 30 ${\mu}A$, 60-90 min irradiation), the recovery of enriched oxygen via cryogenic pumping; The 2nd irradiation for the recovery of absorbed radiofluorine (12.0 bar of 1% $[^{19}F]fluorine/argon$ gas, 13.2 MeV protons, 30 ${\mu}A$, 20-30 min irradiation) the recovery of $[^{18}F]fluorine$ for synthesis. The yield of $[^{18}F]fluorine$ at EOB (end of bombardment) was achieved around $34{\pm}6.0$ GBq (n>10). Conclusion: The production of $^{18}F$ electrophilic agent via $^{18}O(p,n)^{18}F$ reaction was much under investigation. Especially, an aluminum gas target was very advantageous for routine production of $[^{18}F]fluorine$. These results suggest the possibility to use $[^{18}F]F_2$ gas as a electrophilic substitution agent.

Synthesis of Cyclen-Based Copper Complexes as a Potential Estrogen Receptor Ligand (에스트로젠 수용체 리간드로서 사이클렌을 기본 구조로 한 구리 착물의 합성)

  • Park, Jeong-Chan;Pandya, Darpan N.;Jeon, Hak-Rim;Lee, Sang-Woo;Ahn, Byeong-Cheol;Lee, Jae-Tae;Yoo, Jeong-Soo
    • Nuclear Medicine and Molecular Imaging
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    • v.41 no.4
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    • pp.326-334
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    • 2007
  • Purpose: The estrogen receptor (ER), which is over-expressed in ER-positive breast tumors, has been imaged by positron emission tomography (PET) using $[^{18}F]$ labeled estrogen ligands, especially $[^{18}F]FES$. However, $[^{18}F]$ has relatively short-lived half-life ($t_{1/2}$ =1.8 h) and the labeling yield of radio-fluorination is usually low compared with $^{64}Cu\;(t_{1/2}=12.7\;h)$. 1,4,7,10-tetraazacyclododecane (cyclen) is used to form stable metal complexes with copper, indium, gallium, and gadolinium. With these in mind, we prepared cyclen-based Cu complexes which mimic estradiol in aspect of two hydroxyl groups. Materials and Methods: 1.7-Protected cyclen, 1.7-bis (benzyloxycarbonyl)-cyclen was synthesized according to the reported procedure. After introducing two 4-benzyloxybenzyl groups at 4,10-positions, the benzyloxycarbonyl and benzyl groups were removed at the same time by hydrogenation on Pd/C to give 1,7-bis(4-hydroxybenzyl)-1,4,7,10-tetraazacyclododecane (1). Results: The prepared ligand 1 was fully characterized by $^1H,\;^{13}C$ NMR, and mass spectrometer. The synthesized ligand was reacted with copper chloride and copper perchlorate to give copper complexes $[Cu(1)]^{2+}2(CIO_4^-)\;and\;[Cu(1)Cl]^+Cl^-$ which were confirmed by high-resolution mass (FAB). Conclusion: We successfully synthesized a cyclen derivative of which two phenol groups are located on trans position of N-atoms. And, two Cu(ll) complexes of +2 and +1 overall charge, were prepared as a potential PET tracers for ER imaging.

Efficacy and Safety of Red Ginseng on Women's Health Related Quality of Life and Sexual Function (여성의 건강관련 삶의 질과 성기능에 대한 홍삼의 효과 및 안전성 연구)

  • Kim, Dong-II;Choi, Min-Sun;Alm, Hong-Yeop
    • Journal of Ginseng Research
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    • v.33 no.2
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    • pp.115-126
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    • 2009
  • To evaluate the efficacy and safety of red ginseng on women's health-related quality of life (QOL) and sexual function. A randomized, double-blind, placebo-controlled, crossover clinical study was performed. The main efficacy was measured using the Female Sexual Function Index (FSFl) and the 36-Item Short-Form Health Survey (SF-36). Twenty-four healthy, married women aged 30-45 years with FSFl scores below 25 were randomly divided into two groups: the red-ginseng group (N=12) and the placebo group (N=12). During the first six-week period (Study 1), each group was given red ginseng or placebo twice a day. Before the start of the second six-week period (Study 2), a crossover design was chosen with a two-week break (washout period). Interchanging the two groups after the washout period, red ginseng and placebo were given to each group. The outcomes were measured before and after each six-week period. Overall, 23 participants completed the study. In Study 1, the changes relative to the baseline in the FSFl total score were 22.50% and 22.99% for red ginseng and placebo, respectively. In Study 2, the relative changes were 8.14% for red ginseng and 6.29% for placebo. The results showed a greater improving trend in Study 1 with respect to all of the participants' sexual functions, but no significant difference was found between the groups (P=0.9567). After taking red ginseng, all the participants exhibited an improving trend in the desire domain of FSFl, but no significant difference was shown. In the measurement of SF-36, no significant difference was likewise shown. After taking red ginseng, though, all the participants exhibited an improving trend in the physical functioning (PF) domain of SF-36, with no significant difference. Moreover, there was no significant adverse event related to red ginseng. The QOL and sexual function of the study participants in the red-ginseng group were mostly improved, but no statistically significant effect of red ginseng was shown. It is supposed that this result was partly due to the affirmative impression of red ginseng in Korea. Thus, it is anticipated that a long-term clinical trial will show a significant effect of red ginseng on the QOL and sexual function.

A study on monthly changes in morphological characteristics of Ecklonia cava(Laminariales, Phaeophyceae) aquaculture population (갈조류 감태(Ecklonia cava Kjellman) 양식 개체군 형태 형질의 월 변화에 대한 고찰)

  • Seung-Oh Kim;Hyun Il Yoo;Jin Seok Heo;Si Hyun Jeon;Sang-Rae Lee;Jung Hyun Oak
    • Korean Journal of Environmental Biology
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    • v.42 no.1
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    • pp.80-94
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    • 2024
  • This study aimed to examine the morphological characteristics and variation in main traits by comparing the growth of individuals of Ecklonia cava Kjellman(Laminariales, Phaeophyceae) under an aquaculture environment. This survey was conducted from April 2018 to November 2019 at the aquafarm in Jindo-gun, Jeollanam-do(South coast of Korea). To classify the morphology of individuals in the aquaculture farm of E. cava, we investigated fourteen morphological characteristics and calculated four ratios between the measured values. Juvenile individuals showed a simple or oblong lanceolate, and at 3-4 months, a short stipe and holdfast developed, along with a bladelet that developed into the secondary blade form. At 5-7 months, secondary blades were found to develop irregularly on the primary blade. At 8-10 months, the primary blade expanded and secondary blades elongated. At 11-12 months, the secondary blades became oblong. At 13-14 months, the thallus area expanded. At 15-16 months, tertiary blades were formed, the thallus became more complex, the stipe thickened, and the holdfast widened. At 17-18 months, secondary blades clearly developed along with lobes. At 19-20 months, tertiary blades developed and became similar to mature natural blades. In the principal component analysis (PCA), the monthly population of the first year(Q1) and that of the second year(Q2) of the cultured population were divided along PC1, which is related to secondary blade morphological characteristics and the holdfast width. Q2 and natural populations are distributed in descending order of volume in Jeju(J), East Coast(E), and South Coast(S) along PC2, which is related to primary blade and stipe morphological characteristics. The results of this study were judged to offer important criteria for the development of different varieties of E. cava.

A Study on the Economical Nutrition Supplement of Cereal Food for Improvement in our National Eating Habits (국민식생활(國民食生活) 향상(向上)을 위(爲)한 곡류제품(穀類製品)의 경제적( 經濟的) 영향강화(營養强化)에 관(關)한 연구(硏究))

  • Ju, Jin-Soon;Yu, Jong-Yull;Kim, Sook-He;Lee, Ki-Yull;Han, In-Kyu
    • Journal of Nutrition and Health
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    • v.6 no.1
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    • pp.1-9
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    • 1973
  • I. Subject of the Study: Studies on the economical nutrition supplement of cereal foods for the improvement in our notional eating habits. II. Purpose and Importance of the Study: 1. Our nation is confronted with the situation that the rice, a principal food, short of some essential amino acids, lysine and threonine, leads to imbalanced meals insufficient in the nutrient of protein, to bring many difficulties in the elevation of our national physique. 2. The shortage of even the rice imperfect in the nutrient of protein makes the import of lots of foreign rice inevitable. It is considered that the protein supplement and decrease in the consumption amount, of rice, is a serious key to the solution of our food difficulty, and then a way of the proetin supplement of rice through the addition of essential amino acid is to be rarely applied in the view of the our present finance and situation. 3. In the present experiment, therefore, it aims to the suggestion of an aspect of the improvement in our national eating habits guiding in the nutrition elevation which our nation can afford economically through the development of first, a way of the protein supplement by the mixture of cereals producted plentifully in our country, and second, a way of the decrease in the consumption amount and the improvement in the nutrition of rice through the substitution of the other cereals for rice. III. Contents of Scope of the Study: 1. Objects of the study: Objects of the study are the following three items; a) The nutrition supplement of rice through the mixture of cereals. Our nation makes mainly rice as a principal food, but practically many kinds of cereal are produced in our country. They contain different levels and qualities of each nutrient and they are different from one another in the kinds of essential amino acid consisting protein. For that reason, the mutual complement efficeincy of insufficient nutrients is observed through the mixture of cereals. b) The nutrition supplement of rice through the addition of superior protein sources to rice, a principal food. The development of rice as superior foods in the sense of nutrition is conducted through the risement in protein quality by the addition of protein sources in good quality, for example, fish flour (anchovy flour), egg powder, milk powder, and so on, and through the supplement of vitamins and minerals. c) The decrease in the consumption amount of rice through the substitution of the other cereals for rice, as a principal food. The compensation for the short amount of rice is made by the reduction in the consumption of rice through the discovery of a way of substitution of the other cereals for rice, as a principal food and of the settlement of problems in nutrition and finance subsequent to this. 2. Contents of the study: a) An ideal mixture-ratio of cereals is established for rats by feeding mixed foods(rice-barely or rice-wheat) containing 5%, 15%, 25%, 35% and 45% level of either barely or wheat. b) The nutritive value is determined in the whole subsititution of other foods for rice, and then, a way of the complement of over and under nutrients is devised. c) The ideal combination is investigated for rats through feeding mixed foods of main food, rice and supplement foods of protein sources, soy bean, fish flour, egg powder and milk Powder. d) According to results from the above three experiments, the concise functional test for men and the examination of economical property are made. 3. Scope of the study: a) The observation of the effect of each diet on the growth rate for rats. The growth rate of rats was observed for 15 groups of mixed foods of a main food, rice, and wheat flour, barley powder or soy bean powder, respectively, and 12 groups of wheat flour diets supplemented with $1{\sim}3%$ milk powder, and rice or wheat flour diets supplemented with 5% of milk powder, egg powder, fish flour or soy bean powder, respectively. b) The determination of food consumption. The food consumption was determined at weekly intervals for 27 kinds of diet described in a) item. c) The determination of food efficiency rate. The food efficiency rate for each diet was determined by calculation from the gained body weight and the food consumption amount at the same intervals described in b) item. d) The determination of protein efficiency rate. The protein efficiency rate for each diet was determined by calculation form gained body weight and the protein amount of the food consumption amount at the same intervals described c) item. e) The determination of the body component. The hematocrite and hemoglobin levels in the blood, total nitrogen in the serum, blood sugar, and lipids and glycogen in the liver were determined. f) The observation of nitrogen balance. As a means of the observation of nitrogen balance, the total nitrogen in the urine was determined. g) The analysis of economical property. The economical property was analyzed as the gained body weight to the amount equivalent to one won through the conversion of the food consumption amount into money. h) The functional test for men. The concise functional test for men was made in order to establish if the best diet for experimental animals can be applied to men. IV. Results of the Study: The national food product plan, nationwide nutritive enlightment and the improvement activities in our country eating habits, especially, mixed and powder food problems are to be significantly referred, and the following results must be applied. a) In the mixed foods of cereals, the mixed food of the rice-barley containing $5{\sim}15%$ level of barley is best in terms of nutrition. b) The addition of superior protein sources, egg, Bilk, soy bean, or fish, respectively to either rice or wheat flour makes a great risement in the nutritive value. c) The animal protein is more effective in the elevation of nutritive value of cereals. d) Rice takes the most nutritive operation and has the highest preference, among rice, wheat flour and barley. e) Wheat flour is more economical than rice in evaluation of the gained body weight to the regular money, and the addition of fish or soy bean is more economical than that of any other supplement food. But the above results are true of the range of nutrition and economical property. f) The study on the nutrition composition and barley will lead to the improvement in our national eating habits as mixed food of the rice-barley containing $5{\sim}15%$ level of barley is more nutritive. g) This study on the nutrition only for the growing animal can not be considered as a perfect and entire evaluation. Consequently, the perfect data for our national nutrition can be obtained from the experiment similar to this for the much longer period examining, in details, the growth rate, change of physical strength, mental and bodily change, average life span, and resistance ability to infectious diseases.

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A Study of Insomnia and Depression of Elderly Welfare Facility Users in a City (일 도시 노인복지시설 이용자들의 불면증 및 우울증에 대한 연구)

  • Jo, Mo A;Kim, Hyun;Lee, Kang Joon
    • Korean Journal of Psychosomatic Medicine
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    • v.25 no.2
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    • pp.200-209
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    • 2017
  • Objectives : The aim of this study was to analyze the relationship between depressive symptoms and sociodemographic factors associated with geriatric depression and insomnia and to examine the effects of these factors on depression. Methods : The severities of insomnia and depression in elderly aged 60 and older lived in Gwangmyeong city were evaluated and the related sociodemographic factors were investigated. From April 20, 2016 to December 1, 2016, Gwangmyeong city Mental Health Sevices consignment by department of psychiatry of a university-affiliated general hospital conducted surveys and interviews for total 837 elderly peoples lived in Gwangmyeong city by visiting welfare center and wards located in the city. Structured interviews were conducted using Insomnia Severity Index(ISI) and Short form-Geriatric Depression Scale(S-GDS) to examine the relationship between sociodemographic factors and the severities of insomnia and depression. Results : There were significant differences in S-GDS mean scores and age(below 70 years old, 70s, 80s, above 90 years old), type of health care(health insurance, medical aid), type of residency(own, not own) and marital status(single, married, divorced or widowed).There was a significant difference in education level, especially between not educated(and/or) elementary graduates and college graduate(F=3.227, p=0.012). Also, there were significant differences in age, type of health care, type of residency, number of household on divided S-GDS score above and below 10 scores(p<0.05). Insomnia measured by ISI was not significantly associated with sociodemographic factors(p>0.05), but was significantly associated with depressive symptoms(p<0.05). These findings suggest more severe insomnia symptom indicated the higher probability of depression and elderly with depressive symptoms had more severe insomnia. Conclusions : Geriatric depression has significant relationships with age, type of health care, type of residency, marital status, education and number of households. In addition, insomnia which is main symptom of depression in elderly, has important role in predicting the severity and diagnosis of depression.

Analysis and Improvement Measures on the Status of the Installation and Operation of Facilities for Recycling Food Waste into Compost (음식물쓰레기 퇴비화시설의 설치 및 운영 현황분석 및 개선방안)

  • Ryu, Ji-Young;Kong, Kyu-Sik;Shin, Dae-Yewn;Phae, Chae-Gun
    • Journal of the Korea Organic Resources Recycling Association
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    • v.12 no.3
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    • pp.95-111
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    • 2004
  • This research sought to determine the status of the installation and operation of composting facilities of domestic public resource-making facilities and come up with corresponding improvement measures. The composting facilities were the most extensively installed of related facilities with over a 0.5 ton treated volume per day. The monthly and yearly carry-in volume of food waste were found to stand at 1,101.7 tons per day and 930.9 tons per day, thus falling short of the average planned volume of 1,270.9 tons. Many composting facilities, which were installed in areas for which factory registration were not approved, did not get approvals. Composting facilities underwent operation stoppage mainly due to faulty fermentation and crushing equipment. Mainly metals contained in food waste caused faults to the crushing equipment, thus requiring a facility designing against faults and corrosion. The initial water content was found to stand at 50-60%, thus complying with the requirement. However, since the composting food waste had an appropriate mixture of sawdust, food waste, and returned compost, it should meet the initial conditions. For fermentation facilities, the duration time for fermentation was 15 days, and post-fermentation tanks required 21 days of duration time, thus establishing the minimum criteria. However, some facilities did not meet the requirements, taking more time in decomposition, thus suggesting a need to determine the duration time according to facilities. In composting food waste, microorganism-based thermal oxidizer-operated fermentation tanks should be used to ensure an economic operation. On the contrary, 14 out of 25 survey targets heated fermentation tanks in any form. These thermal facilities contain the growth of bacteria, lowering chemical reaction in composting; thus composting facilities should be basically designed to use microorganism-based thermal oxidizers in drying water. An average daily volume of food waste and supplementary materials that was injected in producing compost was 22.8 tons. This volume produced 7.3 tons of compost per day, decreasing 68%. Properties of produced compost were analyzed by its color, absence or presence of remaining decomposition heat, and smell, to assess the quality. As a result, the composting process was not properly installed nor operated in about 50% of composting facilities. Compost should be produced to be soil-friendly.

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MUSIC THERAPY FOR ADOLESCENTS WITH CONDUCT DISORDER (품행장애 청소년의 음악치료 사례연구)

  • Jhin, Hea-Kyung;Kwon, Hea-Kyung
    • Journal of the Korean Academy of Child and Adolescent Psychiatry
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    • v.11 no.1
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    • pp.110-123
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    • 2000
  • The short-term music therapy was performed for adolescents with conduct disorder admitted to Seoul National Mental Hospital for 3 months from Jun to September, 1998. This case study focused mainly on two female patients who participated regularly in the group music therapy. The music therapy process was divided into three phases;beginning, opening up, and closing. This music therapy session consisted of three parts;hello song as beginning, various musical activities, and sound & movement activity as closing. Free musical improvisation, song discussion, musical monodrama, and sound & movement were the mainly applied techniques. Free improvisation was used to enhance, motivate, identify and contain the adolescents' feelings and ideas. Song discussion was used to convey their thoughts and to support each other. Musical monodrama was used to make them have insights into interpersonal relationships. Sound & movement was used to enhance spontaneity. It made them explore their body and voice as an expressive medium. Throughout three months period of music therapy, patient A's communication skill, socialization, and behavior areas were assessed with improvement. She could use music as a symbolic form and was able to share her feelings about herself and her family. Patient B's self-expression and cognitive areas were assessed with improvement. She became more spontaneous and could verbalize her emotions during the group session. Music as a non-verbal and therefore often a non-threatening medium wherein so much can be expressed provided two female patients an atmosphere where a sense of trust may be regained.

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Limit Pricing by Noncooperative Oligopolists (과점산업(寡占産業)에서의 진입제한가격(進入制限價格))

  • Nam, Il-chong
    • KDI Journal of Economic Policy
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    • v.12 no.1
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    • pp.127-148
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    • 1990
  • A Milgrom-Roberts style signalling model of limit pricing is developed to analyze the possibility and the scope of limit pricing in general, noncooperative oligopolies. The model contains multiple incumbent firms facing a potential entrant and assumes an information asymmetry between incombents and the potential entrant about the market demand. There are two periods in the model. In period 1, n incumbent firms simultaneously and noncooperatively choose quantities. At the end of period 1, the potential entrant observes the market price and makes an entry decision. In period 2, depending on the entry decision of the entrant, n' or (n+1) firms choose quantities again before the game terminates. Since the choice of incumbent firms in period 1 depends on their information about demand, the market price in period 1 conveys information about the market demand. Thus, there is a systematic link between the market price and the profitability of entry. Using Bayes-Nash equilibrium as the solution concept, we find that there exist some demand conditions under which incumbent firms will limit price. In symmetric equilibria, incumbent firms each produce an output that is greater than the Cournot output and induce a price that is below the Cournot price. In doing so, each incumbent firm refrains from maximizing short-run profit and supplies a public good that is entry deterrence. The reason that entry is deterred by such a reduced price is that it conveys information about the demand of the industry that is unfavorable to the entrant. This establishes the possibility of limit pricing by noncooperative oligopolists in a setting that is fully rational, and also generalizes the result of Milgrom and Roberts to general oligopolies, confirming Bain's intuition. Limit pricing by incumbents explained above can be interpreted as a form of credible collusion in which each firm voluntarily deviates from myopic optimization in order to deter entry using their superior information. This type of implicit collusion differs from Folk-theorem type collusions in many ways and suggests that a collusion can be a credible one even in finite games as long as there is information asymmetry. Another important result is that as the number of incumbent firms approaches infinity, or as the industry approaches a competitive one, the probability that limit pricing occurs converges to zero and the probability of entry converges to that under complete information. This limit result confirms the intuition that as the number of agents sharing the same private information increases, the value of the private information decreases, and the probability that the information gets revealed increases. This limit result also supports the conventional belief that there is no entry problem in a competitive market. Considering the fact that limit pricing is generally believed to occur at an early stage of an industry and the fact that many industries in Korea are oligopolies in their infant stages, the theoretical results of this paper suggest that we should pay attention to the possibility of implicit collusion by incumbent firms aimed at deterring new entry using superior information. The long-term loss to the Korean economy from limit pricing can be very large if the industry in question is a part of the world market and the domestic potential entrant whose entry is deterred could .have developed into a competitor in the world market. In this case, the long-term loss to the Korean economy should include the lost opportunity in the world market in addition to the domestic long-run welfare loss.

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