• Title/Summary/Keyword: 1940's

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Measurements of Actual Effective Half-Life in $^{131}I$ Therapy for Graves' Hyperthyroidism (그레이브스 갑상선기능항진증 환자의 방사성옥소($^{131}I$) 치료시 실제 유효반감기의 측정)

  • So, Yong-Seon;Kim, Myung-Seon;Kwon, Ki-Hyun;Kim, Seok-Whan;Kim, Tae-Hyung;Han, Sang-Woong;Kim, Eun-Sil;Kim, Chong-Soon
    • The Korean Journal of Nuclear Medicine
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    • v.30 no.1
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    • pp.77-85
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    • 1996
  • Radioiodine($^{131}I$) has been used for the treatment of Graves' hyperthyroidism since the late 1940's and is now generally regarded as the treatment of choice for Graves' hyperthyroidism who does not remit following a course of antithyroid drugs. But for the dose given, several different protocols have been described by different centers, each attempting to reduce the incidence of long-term hypothyroidism while maintaining an acceptable rate control of Graves' hyperthyroidism. Our goals were to evaluate effective half-life and predict absorbed dose in Graves' hyperthyroidism patients, therefore, to calculate and readminister radioiodine activity needed to achieve aimed radiation dose. Our data showed that the mean effective $^{131}I$ half-life for Graves' disease is 5.3 days(S.D=0.88) and mean biologic half-life is 21 days, range 9.5-67.2 days. The mean admininistered activity and the mean values of absorbed doses were 532 MBq(S.D.=254), 112 Gy (S.D.=50.9), respectively. The mean activity needed to achieve aimed radiation dose were 51MBq and marked differences of $^{131}I$ thyroidal uptake between tracer and therapy ocurred in our study. We are sure that the dose calculation method that uses 5 days thyroidal $^{131}I$ uptake measurements after tracer and therapy dose, provides sufficient data about the effective half-life and absorbed dose of $^{131}I$ in the thyroid and predict the effectiveness of $^{131}I$ treatment in Graves' hyperthyroidism.

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Under-Utilization of Women's Education in Korean Labor Market: A Macro-Level Explanation (한국 노동시장에서 여성교육의 저활용: 거시적 차원의 설명)

  • 이미정
    • Korea journal of population studies
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    • v.19 no.2
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    • pp.107-137
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    • 1996
  • Under-utilization of Korean women's education in the labor market has been observed and pointed out as a waste of valuable human resources. Although education provides women with positive returns when they work, it has been found that Korean women's education is not much related to the likelihood of women's labor force participation. This tendency cannot be explained by micro-economic theory, which says that educated women are more likely to participate in the labor force. Thus, in this analysis, a macro-level explanation is attempted to understand Korean women's economic behaviors in relation to education. Korea's rapid industrialization since 1960 has provided ample job opportunities mostly for less educated women. On the other hand, increasing demand for educated female labor has been moderate. Various restriction against women, especially married women, have prevailed in the Korean labor market. Restrictions against women and the marriage bar tend to be selectively applied to decent white-collar jobs, mostly affecting educated women. Furthermore, there has been no shortage of educated male labor due to its adequate supply. Since Korean women spend most of their adult lives in marriage, married women's low participation in the labor force is a critical factor for the low economic returns to women's education throughout their lifetime. Restriction against married women in the labor market also existed in the past of the United States and the Great Britain. However, along with the expansion of the service sector, married women in great numbers flowed into non-manual jobs. The post-1940 increase of married women in the labor force in those countries can be understood to be a result of a labor shortage for non-manual jobs. Also in Taiwan, which shares many common cultural and economic backgrounds with Korea, the marriage bar has been in decline since the late 1970s, along with an increasing demand for female labor in the service sector. In sum, the changes in the demand structure and the supply of educated male labor force will contribute to the lift of the marrige bar in Korea.

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Yoo Young-kuk's Early Constructivism: Utopianism in (1937) (유영국(劉永國)의 초기 구성주의: <랩소디>(1937)에 나타난 유토피아니즘)

  • 유영아
    • The Journal of Art Theory & Practice
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    • no.9
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    • pp.93-121
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    • 2010
  • This study is about Yoo Young-kuk's early works which show constructivism, especially focus on his debut painting, for the 7th Dokuritsu Bijutsu Kyokai(獨立美術協會, the Independent Fine Arts Association) in Tokyo in 1937. The work was painted 2 years after he had started his study in Japan in 1935. It was the first painting that applied Constructivism. played an important role for Constructivism to be a leading art in his abstraction. After this picture, Yoo was soon devoted to the principles of Constructivism-- Faktura(material), Tektonika (tectonics), Tekhnika(technique), space, construction-- in his painterly reliefs. This article examined why Yoo concentrated on Constructivism for , what the characteristics were, and what influences were on other works from 1935 to 1949. In addition, I investigated in which period was painted and how Constructivism was spread in 1930s and early 1940s in chapter 2. I scrutinized Rhapsody in chapter 3. When Yoo created Japan was under the Fifteen Years War(1931-1945), and a major discourse was the Japanese Spirit at that time. It was connected with construction of an ideal nation which the Japanese ultra-national fascism pursued. This ideological pursuit was intended to unite the Japanese people for total war system and to restore a national dignity which had been fallen down due to Manchurian Incident(1931). Thus, on the hand, Kokusai Bunka Shinkokai(國際文化振興, The Society for International Cultural Relations) and the Nippon Kosaku Bunka Renmei(日本工作文化連盟, Japanese Werkbund) were supported financially by the Japanese government. On the other hand, the government enacted regulations to opposing parties which would distract Japanese people's unification. As for the Japanese art world, the merge of art groups was carried out through remodeling of Teikoku Bijutsuin(帝國美術院, The Imperial Fine Arts Academy) in 1935. This brought out continuous dispute and disorder. Young artists who felt difficulty of entering an entry of Imperial Fine Arts Exhibition repeatedly grouped and disbanded for small art groups to build their standing, which they pursued Surrealism and Abstract art. Among them Constructivism was considered as the latest trend and was popular in craft, design, architecture as well as fine arts. In the year before he painted , Avant-garde theatres including Constructivism theatre were introduced in a feature article of September, 1936 in Atelier, which was dealing with mainly avant-garde arts. Books related with Constructivism were translated into Japanese, and Gestaltung Education had become active since the publication of A Compendium of Gestaltung Education("構成敎育大系"(1934)), Salvador Dali(1904-1989) was also introduced, so Surrealism was drawn more attention by young artists. reflected popular trends. Yoo analyzed the Japanese avant-gardists' archaic taste in the Independent Art Association that he submitted his painting to. And then he entitled 'Rhapsody' which derives from Ancient Greek's epic poetry and deliberately set up images in a scene. In chapter 3, I examined a theme which was planned carefully by sorting favorite images from the Japanese Surrealism. was a result that Yoo Young-kuk observed objectively the phenomenon that young artists dreamt of Utopia or longed for Nostalgia passively and lethargically under wars. And then he otherized himself from that circumstance. First of all, for he used the typical icons of Japanese Surrealism such as the horizon, flowing clouds, and vast plain that were considered stereotypes of Arcadia. He, however distinguished himself form those Japanese Surrealists. He made his own vision about Utopia by referring Lyubov Popova(1889-1924)'s stage design. His objective point of view was expressed by positive and dynamic images of structure and human's actions. Constructivism which was attempted in had an effect on other early constructive works, and the principles of Constructivism were sought hard in reliefs, paintings, and photos.

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Changes in the Ceremonial Dresses for Children's First Birthday Since 1945 (광복이후 첫돌 복식의 변천)

  • Ji, Yoon-Young;Hong, Na-Young
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.9
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    • pp.1681-1692
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    • 2001
  • 본 연구는 광복 이후 현재까지 첫돌 복식 변화를 시대적으로 고찰, 그 변화 양상과 영 향 요인을 규명하는 것을 목적으로 하고 있다. 연구 방법은 문헌 고찰과 사진 자료를 통한 내용 분석을 주로 하였다. 더불어 자료의 보충을 위해 첫돌 의례와 관련된 주변 인물들-가족, 기성 아동 한복 유통 상인, 상업적 사진사 등-의 면접 조사도 병행하였다. 이상의 연구를 통해 다음과 같은 결과를 얻었다. 1940년대 중반∼50년대 초에는 해방 이후 혼란과 전란으로 인한 물자의 부족으로 첫돌 의례의 명분은 남아있으나 복식 문화는 공백기를 맞는다. 1950년대 중반이후 60년대 전반기는 미국의 경제 원조와 섬유 공업 활성화로 의료의 공급이 원활하여 전기에 비해 의례적 의미를 지닌 첫돌 복식의 착용이 가능해 졌다. 전통 한복을 기본으로 한 위에 서양식 복식 품목들이 섞여서 나타나고 있다 60년대 후반에서 1970년대의 두드러진 양상은 기성복 산업 의 발달로 전문적 인 기성복 시장이 형성되었고 이는 기성복화 된 첫돌 복식의 일습 개념을 등장시키게 하였다. 또한 한복이 예복화 되는 경 향이 두드러지게 나타났던 시기로 70년대 후반의 칼라 필름의 보급은 금박과 자수와 같은 다양한 재료와 재단 방법을 사용한 장식화 된 첫돌 복식의 사용을 가속화 시 켰다. 특히 70년대 중반에 소수의 일반에게 입혀졌던 궁중복식의 하나인 당의가 소매없는 당의로 바뀌어 여아의 돌옷으로 입혀지기 시작하였다. 1980년대 전반기는 칼라 TV의 보급, 비디오 촬영의 보편화로 한복이던 양복이던 일습화 된 첫돌 복식이 대중적으로 정착하게 되었다. 후반기에는 국내의 국제적인 행사의 유치와 전통 복식 소개를 위한 전시들을 계기로 왕실 복식에 대한 관심이 고조되었다. 이로 인해 여아에게 소매없는 당의를 입히고 남아에게 용포를 입히는 유행이 가속화되었다. 또한 서양식 예복을 입히는 유행이 시작되었다. 90년대에 들어와 아기 전문사진점의 등장은 1 회적인 첫돌 의례에 한복과 서양식 예복, 일상복 등을 다양하게 착용시키는 계기를 가져오게 하였다. 이상과 같은 다양한 변화 양상에도 불구하고 첫돌을 기념하기 위해 특별한 옷을 마련하고자 했으며, 그 복식의 구성 이 전통적인 일습 개념을 꾸준히 지향해 온 경향을 보여주고 있다. 반면 최근 과열된 아동 산업은 보다 다양한 복식을 입혀서 촬영한 사진으로 특별하게 꾸민 상업적인 기념물들을 남겨주게 하고 있다. 비록 특별한 옷을 준비하여 아동에게 입히는 행위는 유사한 표현 양태이나 지나치게 많은 옷을 갈아 입히는 표현 방식은 지양되어야할 것이다

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Surgical Treatment of Bronchial Adenoma - Reports of 17 Cases - (기관지 선종의 외과적 치료[17례 보고])

  • 문석환
    • Journal of Chest Surgery
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    • v.25 no.3
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    • pp.247-257
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    • 1992
  • Bronchial adenoma, firstly described by Muller[1882] had been reported on the subject stressed their benign nature prior to 1940`s, but these tumors including carcinoid tumor, mucoepidermoid carcinoma, adenoid cystic carcinoma, pleomorphic adenoma are now known to possess the various degree of malignant natures from benign course, low grade malignant potential to distant lymphatic or hematogenous metastasis or combination. Although histologically diffeerent, four varieties except carcinoid tumor which is a spectrum of neu-roendocrine tumor originating Kulchitsky cell of the bronchial epithelium and form the part of the APUD tumor spectrum, are morphologically and in many respects clinically similar to the corresponding tumor of the salivary gland is a specific varient of adenocarcinoma that occurs most commonly in the major and minor salivary gland and less frequently tra-cheobronchial tree, esophagus etc. To better understand the clinical characteristics and assess more precisely the malignat nature of bronchial adenoma, we studied 17 cases of bronchial adenoma, which had been experienced at the Department of Thoracic and Cardiovascular surgery of Catholic University Medical College from April 1977 to september 1991. Seventeen cases of bronchial adenoma consist of 2 carcinoid tumors, 6 adenoid cystic carcinomas, 8 mucoepidermoid carcinomas and one pleomorphic adenoma. There is a slight predominace of male patients[10/17] and the age of pt studied varied with a higher incidence occurring between the ages of 40 years and 60 years[mean age, 46.5 years]; the youngest being 15 years and oldest 69 years. Their leading complaints were hemoptysis[4], exertional dyspnea[8], fever & chilness [4], and symptoms mimicking the bronchial asthma[4]. Diagnosis was aided by the radiologic studies such as chest X-ray, polytomography, CT scan, brochography and bronchoscopy. The preferred locations of fumor were in the trachea[4], main stem bronchus[3], bronchus intermedius[3], bronchus of RUL[2], LUL[1], RLL[1], LLL[3] with no peripheral location. Modalities of treatments were single or combination of surgical resection, radiation therapy, chemotherapy. Complete resections were permitted in 12 cases with late recurrences of 4 cases ranging from 6 months to 10 years: pneumonectomy[4], lobectomy[4], bil-obectomy[2], sleeve resection[2]. Gross findings of resected specimens in 14 cases showed that 4 cases were polyp-like pedunculated mass[entirely intraluminal mass] with intact mucosa, 8 cases were broad-bas-ed sessile mass[predominatly intraluminal] and the main portions were located below the mucosa similar to tip of iceburg[predominantly extraluminal] in 2 cases. Follow-up information was availble in all 17 cases ; eight were alive without evidence of disese ranging from 1 month to 13 years. But seven cases died of the causes related to tumor[6 cases within 12 months, one case 10 years after pneumonectomy]. We concluded that 8 cases[47%] of 17 cases were metastasizing bronchial adenoma and precise survival rate cannot be answered by the scanty materials available for study.

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Animal Home Range Estimators - A Review and a Case Study - (동물 행동권 분석 방법론 고찰 - 괭이갈매기 사례 분석과 시사점 -)

  • Lee, Sung-Joo;Lee, Who-Seung
    • Korean Journal of Environment and Ecology
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    • v.36 no.2
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    • pp.202-216
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    • 2022
  • Animals exhibit certain behaviors and movement patterns as they react to their internal needs, external stimuli, and surrounding environments. They have a bounded range in which they mostly spend their time, and it is referred to as a home range. Based on the fact that the home range is a critical area for the survival and preservation of species, there has been a growing body of research on developing more precise home range estimation methods to use the estimated ranges as a ground for establishing an effective conservation policy since the early 1940s. Recent rapid advancements in telemetry technology that resulted in the presence of autocorrelation between locations with short time intervals revealed the limitations of the existing estimators. Many novel estimators have been developed to compensate for it by incorporating autocorrelation in calculating home ranges. However, studies on the animal home range are still in their early stage in Korea, and newly developed methodologies have not yet been adopted. Therefore, this study aims to introduce the foreign home range estimation methods and foster domestic research activities on home ranges. Firstly, we compared and contemplated seven estimators by categorizing them into geometrical and statistical methodologies and then divided them into estimators that assume independent observations and those that consider autocorrelation in each category. After that, the home ranges of black-tailed gulls (Larus crassirostris) were calculated using GPS tracking data for the month of June and derived home range estimators by applying the methodology introduced in this study. We analyzed and compared the results to discuss the strengths and weaknesses of each method. Lastly, we proposed a guideline that can help researchers choose an appropriate estimator for home range calculation based on the animal location data characteristics and analysis purpose.

A Study on a Quantitative Method in Estimating Forest Effects for Streamflow Regulation (II) - Mainly Dealing with Application of Coefficient for Slope Roughness - (삼림이수기능(森林理水機能)의 정량적(定量的) 평가방법(平價方法)에 관한 연구(硏究)(II) - 조도계수(粗度係數)의 응용(應用)을 중심(中心)으로 -)

  • Lee, Heon Ho
    • Journal of Korean Society of Forest Science
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    • v.81 no.4
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    • pp.337-345
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    • 1992
  • In this research, a kinematic wave model was applied for the runoff analysis, Regulation of streamflow was estimated by the calibration of roughness coefficient as a parameter. The data analyzed were obtained from Ananomiya and Shirasaka experimental basins at Tokyo University Forest in Aichi. Estimation methods and characteristics of roughness coefficient as a evaluation method of hydrological function of forest are summarized as follows ; 1. Roughness coefficient($N_s$) indicates the resistance of hillslope to the flowing water of surface runoff. There exists an hypothesis that resistance of hillslope to flowing water increase with the growth forest and development of the $A_o$ layer. 2. Roughness coefficient($N_s$) was estimated by the parameter when the stream direct runoff was calculated by using the kinematic wave. 3. Secular change of '$N_s$' in ananomiya has a curve which has an upper limit and increases exponentially near the limit. The curve quickly increased from 1935 to 1945 when results of afforestation for erosion control were thought to be effective. On the other hand, slight increase of '$N_s$' in Shirasaka indicates that there was not such a big change in the surface of soil layer. 4. The increase of '$N_s$' was related with decrease of direct runoff and increase of base flow. It was recognized that the rate of direct runoff decreased with the improvement of forest physiognomy and the rate of base flow was increased. But absolute value of water runoff per one storm decreased in chronological order.

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A Study on the History and Species of Street Trees in Seoul (서울시 가로수 역사와 수목 고찰)

  • Song, Suk-Ho;Kim, Min-Kyung
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.38 no.4
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    • pp.58-67
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    • 2020
  • The present study was conducted as part of basic research for selecting species of street trees with historical value in Seoul. It also made up a list of traditional landscape trees for a variety of alternatives. The following results are shown below. As to the history of street trees in Korea, records on to-be-estimated street trees are found in historical documents written in King Yangwon during the second year of Goguryeo Dynasty (546) and King Myeongjong during 27 year of Goryeo (1197). However, it is assumed that lack of clarity is found in historical records. During the 23 year of King Sejong in the early Joseon Dynasty (1441), the record showed that the state planted street trees as guideposts on the postal road. The records revealed that Ulmus spp. and Salix spp. were planted as guidance trees. The street tree system was performed in the early Joseon Dynasty as recorded in the first year of King Danjong document. Pinus densiflora, Pinus koraiensis, Pyrus pyrifolia var. culta, Castanea crenata, Styphnolobium japonicum and Salix spp. were planted along the avenue at both left and right sides. Morus alba were planted on streets during the five year of King Sejo (1459). As illustrated in pieces Apgujeong by painter Jeongseon and Jinheonmajeongsaekdo in the reign of King Yeongjo, street trees were planted. This arrangement is associated with a number of elements such as king procession, major entrance roads in Seoul, place for horse markets, prevention of roads from flood and indication. In the reign of King Jeongjo, there are many cases related to planting Pinus densiflora, Abies holophylla and Salix spp. for king procession. Turning king roads and related areas into sanctuaries is considered as technique for planting street trees. During the 32 year of King Gojong after opening ports (1985), the state promoted planting trees along both sides of roads. At the time, many Populus davidiana called white poplars were planted as rapidly growing street trees. There are 17 taxa in the Era of Three Kingdoms records, 31 taxa in Goryeo Dynasty records and 55 taxa in Joseon Dynasty records, respectively, described in historical documents to be available for being planted as street trees in Seoul. 16 taxa are recorded in three periods, which are Era of Three Kingdoms, Goryeo Dynasty and Joseon Dynasty. These taxa can be seen as relatively excellent ones in terms of historical value. The introduction of alien plants and legal improvement in the Japanese colonial period resulted in modernization of street tree planting system. Under the six-year street tree planting plan (1934-1940) implemented as part of expanding metropolitan areas outside the capital launched in 1936, four major street trees of top 10 taxa were a Populus deltoides, Populus nigra var. italica, Populus davidiana, Populus alba. The remaining six trees were Salix babylonica, Robinia pseudoacacia, platanus orientalis, Platanus occidentalis, Ginkgo biloba, and Acer negundo. Beginning in the mid- and late 1930s, platanus orientalis, Platanus occidentalis were introduced into Korea as new taxa of street trees and planted in many regions. Beginning on 1942, Ailanthus altissima was recommended as street trees for the purpose of producing silks. In 1957 after liberation, major street tree taxa included Platanus occidentalis, Ginkgo biloba, Populus nigra var. italica, Ailanthus altissima, Populus deltoides and Salix babylonica. The rank of major street tree species planted in the Japanese colonial period had changed. Tree planting trend around that period primarily representing Platanus occidentalis and Ginkgo biloba still holds true until now.

A Jungian Perspective on 'Spiritual Exercises' of St. Ignatius (이냐시오 '영신수련'에 대한 분석심리학적 고찰)

  • Jung Taek Kim
    • Sim-seong Yeon-gu
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    • v.25 no.1
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    • pp.27-64
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    • 2010
  • The main focus of this article investigates Jung's analytic implications of the Spiritual Exercises by St. Ignatius of Loyola. The Exercises is referred to not only as the tool for transformation that transformed Ignatius from a soldier of the world into a soldier of God and led him to a completely changed life but also as a tool which galvanizes self-realization, i.e., individuation process, in which a faithful experiences the presence of God in his life and is in search for himself in a new way. The interest in the Exercises regarded as a Western version of Yoga of the East which is a tool for transformation led Jung to give a series of 20 lectures on the Exercises in a seminar held in Zurich from 1939 to 1940. Curiosity about Jung's understanding on the Exercises provokes my desire to step into this research. The Exercises is a book for spiritual exercises that prepare and dispose one's soul to rid itself of all disordered attachments and to order one's life. The Exercises is made up of four Weeks. The First begins with 'Principle and Foundation' which illustrates what human beings are created for. It leads retreatants to rid themselves of disordered attachments and to have a new perspective on life by the consideration and contemplation of sins as the subversion of the Principle and Foundation. The Second is the period in which retreatants accept Christ as the Master of their lives through the meditation and contemplation of the life of Christ. In the Third, retreatants take part in the salvation history of Christ not only by actively participating in the Passion of Christ but also by incorporating the Passion into their lives. The Fourth aids retreatants to undergo their transformation and experience it deeply in order to participate in the new life of Christ who by His resurrection overcame death. In conclusion, Jung viewed the Exercises as a Western tool which plays the similar role of Yoga of the East which engenders inner transformation. The four-week-long retreat helps retreatants to meditate on God who unifies everything and is Himself/Herself the perfect union or the unity so that imperfect retreatants are given opportunities to undergo complete metamorphosis into the immortal, indivisible, and impeccable God. Jung understood that this metamorphosis leads human beings to the totality, that is, the genuine self as the image of God. The author interprets that it is the transformation that the Exercises tries to attain, which resonates with individuation, the key element of analytic psychology.

SPECIES OF CULTIVATED PORPHYRA IN KOREA (한국산 양식김의 종류)

  • KANG Jae Won
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.3 no.2
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    • pp.77-92
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    • 1970
  • Ueda, in the course of his systematic work on the lavers, Porphyra, in Japan and Korea in 1932, mentioned that most of the cultivated Porphyra belong to Porphyra tenera Kjellman. Then he, dividing the species into two forms, f. typica and f. kjellmani, put Korean cultivated Porphyra under the latter. From the 1930s to the early 1940s, Fujikawa, Kaneko and others worked on Physiological experiments or cultivational experiments of Porphyra in the culture-bed, but there was no mention about the cultivated Porphyra species. However, many fishermen generally recognize that the characteristics of cultivated Porphyra vary depending on their habitat or the picking season, and it is considered that these differences are due to the varieties of the species which are well adaptable to various environments. Recently, I have become aware of the predominant occurrence of P. yezoensis Ueda in most culture-beds of Korea as in the Tokyo Bay or other places in Japan. At present, since artificial seeding for the cultivation of Porphyra with Conchocelis has been carried out and peculiar species can be cultured, a study of the species of cultivated Porphyra has become an important subject. I collected the specimens from a number of culture-beds which are located in the legions shown in fig. 1 from January, 1968 to May, 1970 and found that there are five species, P. tenera Kjellman, P. yezoensis Ueda, P. kuniedai Kurogi, P. seriata Kjellman and P. suborbiculata Kjellman. Among them, P. kuniedai was treated as a round-type, a form of P. tenera, by Kunieda (1939) and Tanaka (1952) and the occurrence of this form is generally recognized by most fishermen. At present, as mentioned above, the most dominant species of cultivated Porphyra is P. yezoensis but the cultivation of P. tenera is restricted to certain culture-beds or the early half of the cultivation period. P. kunieda appears as a mixed species throughout most of the culture-beds, particulary in the later half of the period, while when it was picked in January it appeared dominantly in a place such as Gum-Dang where the 'Bal', splitted bamboo piece mat, was settled during the last of September. This is the first seeding process. The latter two species, P. suborbiculata and P. seriata appear frequently but in small amounts in the later half of the period particulary in the western region of the southern coast. However, it can not be ascertained when P. yezoensis becomes predominant, because specimens have not been available up until recent years but the process can be described as follows: We commonly recognize the ecological characteristics of P. tenera as follows; First, the conchospores of the species develop earlier and the period of its discharge is shorter than those of P. yezoensis; second, the microscopical buds discharge neutral spores which develop into new buds directly and buds develop repeatedly through a short period. Consequently, according to such above ecological characteristics, the species can grow thick on the 'Bal' exclusively. However, buds may disappear when they are harmed by disease such a 'infection by certain parasites or by other unusual environmental conditions. Thus P. yezoensis are enabled to grow on the 'Bal' instead of the former species since they not only develop later than the former but also macroscopical fronds discharge the neutral spore throughout the period from October to May. Likewise, if any disease appears in the culture-bed ill the later half of the period, the former is more severely damaged than the latter because the former have less resistance to the disease than the latter. Thus fewer frond survive and fewer carpospores which are the origin of the next generation can be discharged. However the latter by their nature can continue growing until early summer. In the case of the culture-bed where the above phenomenon occurs repeatedly P. yezoensis gradually may become the dominant species among cultivated Porphyra. In support of the validity of this process we find that according to the description and the plate of Wada (1941), P. tenera, P. yezoensis and P. kuniedai grow together in the culture-bed at the mouth of the Nakdong River where P. yezoensis occurs predominantly and mixed with P. kuniedai.

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