• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.9 no.1
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• pp.1-18
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• 1973

For regulating the depth of midwater trawl nets towed at the optimum constant speed, the changes in the shape of warps caused by adding a weight on an arbitrary point of the warp of catenary shape is studied. The shape of a warp may be approximated by a catenary. The resultant inferences under this assumption were experimented. Accordingly feasibilities for the application of the result of this study to the midwater trawl nets were also discussed. A series of experiments for basic midwater trawl gear models in water tank and a couple of experiments of a commercial scale gears at sea which involve the properly designed depth control devices having a variable attitude horizontal wing were carried out. The results are summarized as follows: 1. According to the dimension analysis the depth y of a midwater trawl net is introduced by $$y=kLf(\frac{W_r}{R_r},\;\frac{W_o}{R_o},\;\frac{W_n}{R_n})$$) where k is a constant, L the warp length, f the function, and $W_r,\;W_o$ and $W_n$ the apparent weights of warp, otter board and the net, respectively, 2. When a boat is towing a body of apparent weight $W_n$ and its drag $D_n$ by means of a warp whose length L and apparent weight $W_r$ per unit length, the depth y of the body is given by the following equation, provided that the shape of a warp is a catenary and drag of the warp is neglected in comparison with the drag of the body: $$y=\frac{1}{W_r}\{\sqrt{{D_n^2}+{(W_n+W_rL)^2}}-\sqrt{{D_n^2+W_n}^2\}$$ 3. The changes ${\Delta}y$ of the depth of the midwater trawl net caused by changing the warp length or adding a weight ${\Delta}W_n$_n to the net, are given by the following equations: $${\Delta}y{\approx}\frac{W_n+W_{r}L}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}{\Delta}L$$ $${\Delta}y{\approx}\frac{1}{W_r}\{\frac{W_n+W_rL}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}-{\frac{W_n}{\sqrt{D_n^2+W_n^2}}\}{\Delta}W_n$$ 4. A change ${\Delta}y$ of the depth of the midwater trawl net by adding a weight $W_s$ to an arbitrary point of the warp takes an equation of the form $${\Delta}y=\frac{1}{W_r}\{(T_{ur}'-T_{ur})-T_u'-T_u)\}$$ Where $$T_{ur}^l=\sqrt{T_u^2+(W_s+W_{r}L)^2+2T_u(W_s+W_{r}L)sin{\theta}_u$$ $$T_{ur}=\sqrt{T_u^2+(W_{r}L)^2+2T_uW_{r}L\;sin{\theta}_u$$ $$T_{u}^l=\sqrt{T_u^2+W_s^2+2T_uW_{s}\;sin{\theta}_u$$ and $T_u$ represents the tension at the point on the warp, ${\theta}_u$ the angle between the direction of $T_u$ and horizontal axis, $T_u^2$ the tension at that point when a weights $W_s$ adds to the point where $T_u$ is acted on. 5. If otter boards were constructed lighter and adequate weights were added at their bottom to stabilize them, even they were the same shapes as those of bottom trawls, they were definitely applicable to the midwater trawl gears as the result of the experiments. 6. As the results of water tank tests the relationship between net height of H cm velocity of v m/sec, and that between hydrodynamic resistance of R kg and the velocity of a model net as shown in figure 6 are respectively given by $$H=8+\frac{10}{0.4+v}$$ $$R=3+9v^2$$ 7. It was found that the cross-wing type depth control devices were more stable in operation than that of the H-wing type as the results of the experiments at sea. 8. The hydrodynamic resistance of the net gear in midwater trawling is so large, and regarded as nearly the drag, that sweeping depth of the gear was very stable in spite of types of the depth control devices. 9. An area of the horizontal wing of the H-wing type depth control device was $1.2{\times}2.4m^2$. A midwater trawl net of 2 ton hydrodynamic resistance was connected to the devices and towed with the velocity of 2.3 kts. Under these conditions the depth change of about 20m of the trawl net was obtained by controlling an angle or attack of $30^{\circ}$.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.1
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• pp.32-36
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• 2016

Purpose In nuclear medicine examination, $^{131}I$ is widely used in nuclear medicine examination such as diagnosis, treatment, and others of thyroid cancer and other diseases. $^{131}I$ conducts examination and treatment through emission of ${\gamma}$ ray and ${\beta}^-$ ray. Since $^{131}I$ (364 keV) contains more energy compared to $^{99m}Tc$ (140 keV) although it displays high integrated rate and enables quick discharge through kidney, the objective of this study lies in comparing the difference in exposure dose of $^{131}I$ before and after wearing apron when handling $^{131}I$ with focus on 3 elements of external exposure protection that are distance, time, and shield in order to reduce the exposure to technicians in comparison with $^{99m}Tc$ during the handling and administration process. When wearing apron (in general, Pb 0.5 mm), $^{99m}Tc$ presents shield of over 90% but shielding effect of $^{131}I$ is relatively low as it is of high energy and there may be even more exposure due to influence of scattered ray (secondary) and bremsstrahlung in case of high dose. However, there is no special report or guideline for low dose (74 MBq) high energy thus quantitative analysis on exposure dose of technicians will be conducted based on apron wearing during the handling of $^{131}I$. Materials and Methods With patients who visited Department of Nuclear Medicine of our hospital for low dose $^{131}I$ administration for thyroid cancer and diagnosis for 7 months from Jun 2014 to Dec 2014 as its subject, total 6 pieces of TLD was attached to interior and exterior of apron placed on thyroid, chest, and testicle from preparation to administration. Then, radiation exposure dose from $^{131}I$ examination to administration was measured. Total procedure time was set as within 5 min per person including 3 min of explanation, 1 min of distribution, and 1 min of administration. In regards to TLD location selection, chest at which exposure dose is generally measured and thyroid and testicle with high sensitivity were selected. For preparation, 74 MBq of $^{131}I$ shall be distributed with the use of $2m{\ell}$ syringe and then it shall be distributed after making it into dose of $2m{\ell}$ though dilution with normal saline. When distributing $^{131}I$ and administering it to the patient, $100m{\ell}$ of water shall be put into a cup, distributed $^{131}I$ shall be diluted, and then oral administration to patients shall be conducted with the distance of 1m from the patient. The process of withdrawing $2m{\ell}$ syringe and cup used for oral administration was conducted while wearing apron and TLD. Apron and TLD were stored at storage room without influence of radiation exposure and the exposure dose was measured with request to Seoul Radiology Services. Results With the result of monthly accumulated exposure dose of TLD worn inside and outside of apron placed on thyroid, chest, and testicle during low dose $^{131}I$ examination during the research period divided by number of people, statistics processing was conducted with Wilcoxon Signed Rank Test using SPSS Version. 12.0K. As a result, it was revealed that there was no significant difference since all of thyroid (p = 0.345), chest (p = 0.686), and testicle (p = 0.715) were presented to be p > 0.05. Also, when converting the change in total exposure dose during research period into percentage, it was revealed to be -23.5%, -8.3%, and 19.0% for thyroid, chest, and testicle respectively. Conclusion As a result of conducting Wilcoxon Signed Rank Test, it was revealed that there is no statistically significant difference (p > 0.05). Also, in case of calculating shielding rate with accumulate exposure dose during 7 months, it was revealed that there is irregular change in exposure dose for inside and outside of apron. Although the degree of change seems to be high when it is expressed in percentage, it cannot be considered a big change since the unit of accumulated exposure dose is in decimal points. Therefore, regardless of wearing apron during high energy low dose $^{131}I$ administration, placing certain distance and terminating the administration as soon as possible would be of great assistance in reducing the exposure dose. Although this study restricted $^{131}I$ administration time to be within 5 min per person and distance for oral administration to be 1m, there was a shortcoming to acquire accurate result as there was insufficient number of N for statistics and it could be processed only through non-parametric method. Also, exposure dose per person during lose dose $^{131}I$ administration was measured with accumulated exposure dose using TLD rather than through direct-reading exposure dose thus more accurate result could be acquired when measurement is conducted using electronic dosimeter and pocket dosimeter.

• The korean journal of orthodontics
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• v.33 no.6 s.101
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• pp.437-451
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• 2003

The purpose of this study was to measure maximum bite force and to investigate its relationship with anteroposterior, vertical, and transverse facial skeletal measurements. From among the dental students at the College of Dentistry, forty subjects (26 male and 14 female) were selected. With two sets of strain gauge, maximum bite force at the right and left first molars and anterior teeth was measured in the morning and afternoon. After taking lateral and posteroanterior cephalograms, fifty and nineteen variables were evaluated, respectively Paired t-tests and an independent t-test were done and correlation coefficients were obtained. 1. The maximum bite force at the first molars was $68.0\pm13.9kg$. in males and $55.6\pm10.5kg$ in females (p<0.05) while the force at the anterior teeth was $8.4\pm4.9kg\;and\;1.1\pm3.4kg$ respectively (p<0.05). 2. Some tendency for a greater value of maximum bite force at the preferred side was observed but not statistically significant (p>0.05). 3. Significant difference was observed between the strong bite force group and the weak bite force group in some cephalometric and other measurements (p<0.05). N-S-Ar, S-Ar-Go, FH-Hl, IMPA and MMO showed a significant difference in posterior maximum bite force (P). N-S-Ar and FH-H1 also showed a significant difference in anterior maximum bite force (A). 4. Several cephalometric variables showed some correlation with maximum bite force (p<0.05). N-S-Ar, S-Ar-Go, UGA, FH-H6, FH-H1, body weight and MMO were significantly correlated with posterior maximum bite force (P). Go-Me, P-1 and IMPA were significantly correlated with anterior maximum bite force (A).

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.699-716
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• 1998

This study was designed to evaluate the expression of non-collagenous protein in periodontal tissue during the experimental movement of rat incisors, by LSAB(labelled streptavidine biotin) immunohistochemical staining for osteonectin and osteocalcin. Twenty seven Sprague-Dawley rats were divided into a control group(3 rats) and 6 experimental groups(24 rats) where 75g of force was applied from helical springs across the maxillary incisors. Rats of experimental groups were sacrificed at 12 hours, 1, 4, 7, 14 and 28 days after force application, respectively. And the tissues of a control group and experimental groups were studied immunohistochemically and histologically. The results were as follows : 1. Until 28 days after force application, periodontal fibers had been strectched on tension side and compressed in pressure side of all the experimental groups, and the arrangement of periodontal fibers had not been recovered yet. 2. The expression of osteonectin in control group was rare in dentin, cementum and osteocyte, and was mild in odontoblasts and matrix of alveolar bone. 3. The expression of osteocalcin in control group was negative in gingiva, osteoblasts, osteocyte and cementum, and was rare in predentin, capillaries in pulp and periodontal ligament and the matrix of alveolar bone. 4. There was no difference in the expression of osteocalcin or osteonectin in dentin, cementum, pulp, odontoblasts, between of control and of experimental groups. 5. The expression of osteonectin in intermaxillary suture got the peak in 7-day and was declined after 14-day. The expression of osteocalcin remained in a same degree since it became mild in 14-day. 6. The expression of osteonectin in pressure side of periodontal ligament of experimental group was rare, which was similar to control group. But in tension side, it was increased until 14-day aftrer which it was declined. 7. The expression of osteocalcin in periodntal ligament was rare in 12-hour to 14-day, but became severe in 28-day, which was greater in tension side than in pressure side, and in the periodontal fiber next to alveolar bone than to tooth surface. 8. The expression of osteocalcin in alveolar bone was rare until 14-day in pressure side, but became moderate in 28-day. The expression of osteonectin was increased from 7-day by time dependency, which was greater in tension side than in pressure side.

• Journal of Korean Society of Forest Science
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• v.53 no.1
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• pp.44-55
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• 1981

Neutral sulfite precooked fir chips were refined in the Asplund Laboratory Defibrator at various temperature ($20^{\circ}C$, $120^{\circ}C$ and $180^{\circ}C$). The effects of refining temperatures on the physical property and morphological structure of the resulting pulps were discussed. Yields of precooked chips (84%, 92% and 100%) and refining temperature affected remarkably the yield of refined pulp, its beatability, sheet strength and morhphological characteristics. Pulp yield and beatability decreased with increasing refining temperature. Fiber surface of unbeaten pulp from precooked chips of 84% yield was to some extent covered by the secondary wall, while that of the pulp form precooked yield of 92% by the compound middle lamella. In the case of uncooked chips, fibers were damaged heavily, and the exposed fiber surface resulted from the equal amount of the secondary wall and the compound middle lamella. In the case of pulps prepared from precooked chips of higher yields (92% and 100%), sheet strength increased linearly as sheet density increased. But at the same sheet density, pulp from lower precooked yield (84%) had better sheet strength after open discharge refining as compared to pressurized refining, because pulp from the former had much amounts of fines fraction of higher water retention value than the latters. And there was observed a little difference in fiber length distribution but nearly similar in its morphology with increasing refining temperature.

• Journal of Nutrition and Health
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• v.42 no.3
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• pp.278-290
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• 2009

This study aims to evaluate the changes of flavonoid contents and antioxidants activity of Jeju native citrus fruits juice according to the harvest date. Flavonoids such as quercatagetin, narirutin, hesperidin and neohesperidin were contained most plentifully in the juice of Jigak (Citrus aur-antium) by 573.73 mg/100 mL, Sadoogam (C. pseudogulgul) by 393.99 mg /100 mL, Soyooja by 29.63 mg/100 mL and Jigak (C. aurantium) by 201.23 mg/100 mL in the late August, respectively. The highest contents of nob-iletin, sinensetin and tangeretin among polymethoxyflavones were found in the juice of Hongkyool (C. tachibana) by 7.39 mg/100 mL, 2.24 mg/100 mL, 0.63 mg/100 mL in the late August, respectively. 3,5,6,7,8,3',4'- Heptamet- hoxyflavone recorded the highest amount in Punkyool (C. tangerina) by 0.27 mg/100 mL in the late August, but the other polymethoxyflavones including 3',4',7,8-tetramethoxyflavone, 3',4'-dimethoxyflavone, 4'-methoxyflavone, 5,6,7,3',4',5'-hexamethoxyflavone, scutellarein tetramethylether were observed only trace amount in all the citrus fruits. Flavonoid contents in the citrus fruit juices were the highest during early maturation and decreased rapidly while ripening. Total polyphenol contents were the highest in the late August and decreased with ripening. However from the late December, the contents were increased again. Antioxidant activities of the fruits were evaluated as electron donating ability and were the lowest in the late September and increased with the fruit ripening. These results suggest that quercetagetin among all the flavonoids was most plentiful in Jigak and Dangyooja (C. grandis), so that the fruits could be used for industrial material of flavonoids and antioxidant agents.

• The Korean Journal of Air & Space Law and Policy
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• v.8
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• pp.231-248
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• 1996

이 논문(論文)은 한국(韓國)의 우주(宇宙) 산업(産業) 발달(發達)과 그 과정(過程)을 고찰(考察)하고 현재 진행 중인 통신위성(通信衛星)의 개발(開發)과 그 사업(事業)을 뒷받침해 주는 국가(國家)의 정책(政策)을 살펴보고 있다. KOREASAT라고 명명(命名)된 통신위성(通信衛星) 개발(開發)에 현재 여러 기관이 관계(關係)하고 있으나 그 중 KARI(한국항공우주연구소(韓國航空宇宙硏究所)), ETRI(전자통신연구소(電子通信硏究所)), SERI(시스템공학연구소(硏究所)), KAIST(한국과학기술연구소(韓國科學技術硏究所)) 등이 중추적인 연구(硏究)를 하고 있다. 특히 이 논문(論文)에서는 아래와 같은 문제(問題)를 다루고 있다 첫째, 최근(最近) 한국우주개발(韓國宇宙開發) 상황(狀況) 둘째, 장기(長期) 우주개발(宇宙開發) 계획(計劃) 셋째, 현재(現在) 우주개발(宇宙開發) 상황(狀況)과 미래(未來) 우주개발(宇宙開發)에 관련한 정책(政策)적 문제(問題) 넷째, 한국(韓國) 우주개발(宇宙開發)과 정책(政策) 방향(方向)에 대한 의견(意見) 최근의 한국우주개발(韓國宇宙開發) 상황(狀況)은 크게 한국(韓國)의 통신위성(通信衛星) 사업(事業)인 Koreasat program과 다목적 위성사업(衛星事業)인 KOMSAT로 나타나는데 한국(韓國)의 최초 상업용(商業用) 위성(衛星)인 Koreasat는 1호가 1995년도에 발사(發射)되었으나 정상궤도(正常軌道) 진입(進入)에 문제(問題)가 발생하여 발사업체(發射業體)로부터 보상문제(補償問題)가 제기(提起)되기도 하였으나 2호는 성공리에 발사(發射)되었다. 미국항공우주회사(美國航空宇宙會社)와 공동(共同)으로 개발(開發)중인 새로운 과학위성(科學衛星)인 KOMSAT는 한국우주과학기술(韓國宇宙科學技術)을 한단계 더 발전(發展)시킬 수 있을 것이고 1999년도에 발사(發射) 계획(計劃)이다. 한국항공우주연구소(韓國航空宇宙硏究所) 중심(中心)의 장기(長期) 우주개발(宇宙開發) 계획(計劃)에서 제시(提示)하는 4가지 우주개발(宇宙開發)의 기본목표(基本目標)는 첫째, 우주산업응용산업(宇宙産業應用産業)의 상호협조개발(相互協助開發)에 의한 우주산업(宇宙産業) 육성(育成) 둘째, 한국(韓國)의 현재 우주산업상황(宇宙産業狀況)에 알맞은 특정분야(特定分野)를 선정(選定)하고 이 분야(分野)에서 최단기에 세계(世界) 최고의 기술수준을 성취(成就)하도록 집중(集中) 셋째, 외국과 긴밀한 협조(協助)로 선진기술(先進技術)의 습득(習得) 넷째, 체계적이고 통합(統合)된 장기우주산업발전(長期宇宙産業發展) 계획(計劃) 성립(成立) 등이다. 이러한 계획(計劃)에 주요 사안(事案)으로는 2015년까지 19기의 인공위성(人工衛星) 보유(保有)를 위한 제작계획(製作計劃)과 2010년까지 발사체(發射體) 개발(開發)을 마련하는 것이다 현재 우주활동(宇宙活動)에 관련된 문제(問題)는 주로 Koreasat의 서비스와 사용계획(使用計劃)에 대한 것으로 위성개발사업(衛星開發事業)에 있어서 관련 정부부서간(政府部署間)에 의견(意見)을 달리하고 있는 형태이다. 한국통신(韓國通信)과 정보통신부(情報通信部)는 위성(衛星)의 DBS 트랜스폰더에 대해 디지털 방식(方式)을 적용(適用)할 것을 제안(提案)했지만 공보처(共報處)는 반대(反對)의 입장(立場)을 표명(表明)한 것과 방송국(放送局)의 관리(管理)와 통제(統制)는 공보처(共報處)에 있고 무선통신표준(無線通信標準)에 대한 면허(免許)는 정보통신부(情報通信部)에 있기 때문에 방송국(放送局)에 대한 면허(免許)는 각기 다른 두 단계(段階)로 구성(構成)되는 문제(問題)가 발생(發生)한다. 또한 DBS 서비스에서 사기업(私企業)의 참여(參與)와 관련하여 재벌(財閥)의 참여(參與)를 허용(許容)하느냐의 여부(與否)의 논쟁(論爭)이다. 다음으로 미래(未來) 우주산업개발(宇宙産業開發)에 관한 정책문제(政策問題)를 살펴보면 국가적(國家的) 차원(次元)에서 조직적(組織的)인 육성책(育成策)에 대한 문제(問題)로 현재 주관 부처가 과학기술처(科學技術處)와 통상산업부(通商産業部)로 나뉘어 추진(推進)되고 있다는 점이다. 그리고 차세대(次世代) 통신위성개발(通信衛星開發) 계획(計劃)에 대한 문제(問題)로 최소 2${\sim}$4개의 궤도확보(軌道確保)와 이미 정상궤도(正常軌道) 진입(進入) 실패(失敗)에 따른 Koreasat 1호의 생명단축(生命短縮)으로 새로운 통신위성(通信衛星)을 4년이내에 발사(發射)해야 한다는 문제(問題)이다. 결론적으로 장기(長期) 우주개발계획정책(宇宙開發計劃政策)에 있어서 첫째, 국제적 우주개발사업(宇宙開發事業)에 대한 적극적(積極的) 참여(參與), 둘째, 우주(宇宙)에서 독립적(獨立的)인 활동(活動)을 할 수 있는 국가안보체제(國家安保體制)의 개발(開發), 셋째, 국가(國家) 위상(位相)의 발전(發展)과 우주개발(宇宙開發)을 위한 인력활용(人力活用)의 개발(開發), 넷째, 무한한 우주(宇宙)에 도전(挑戰)할 수 있는 우수(優秀)한 인재(人才)의 교육(敎育), 다섯째, 21세기를 대비(對備)하여 한국(韓國)의 우주개발정책(宇宙開發政策)의 결정(決定) 등이 고려(考慮)되어야 할 5가지 요소(要所)들이다. 그리고 막대(莫大)한 비용(費用)이 드는 우주개발사업(宇宙開發事業)을 효율적으로 추진(推進)하기 위해서는 국가(國家) 최고(最高) 지도자(指導者)의 직접지휘(直接指揮)를 받는 정부기구(政府機構)가 수립(樹立)되어 정부차원(政府次元)에서 추진(推進)하되 산학연(産學硏)이 협조(協助)하여 우주개발계획(宇宙開發計劃)을 추진(推進)하여야 할 것으로 본다.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.87-93
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• 2008

Bacillus thuringiensis with selected high toxicities against tobacco cutworm, Spodoptera litura were isolated from domestic soils. When being observed under a phase-contrast microscope, the insecticidal crystal proteins were showed a bipyramidal crystal types. New CAB 109 isolate was identified to B. thuringiensis subsp. aizawai in the H serotype. As a results of insecticidal activities between CAB 109 isolate and 3 existing ready-made products against 3rd larva of S. litura, CAB 109 isolate showed 100% mortality with spore concentration $(1.3{\times}10^7cfu/ml)$. It was a very high insecticidal activity compared with a existing ready-made B. t. products. $LD_{50}$ values of CAB 109 isolate was $9.78{\times}10^5,\;6.87{\times}10^6\;and\;1.83{\times}10^7cfu/ml$ spore concentration against 2nd, 3rd and 4th larva of S. litura, respectively. Unlike Plutella xylostella, S. litura was slowly died after application up to 7 days. The weight of S. litura larva applied with CAB 109 isolate were 6-7 times less than controlled group. Even though it didn't die, it did not grow into next larva. The result observed with scanning electron microscope was that CAB 109 isolate of B. t. aizawai formed a typical bipyramidal crystal protein type. Otherwise, when CAB 109 isolate was examined with SDS-PAGE and with trypsin, there was no difference between CAB 109 strain and ready-made products of B. thuringiensis.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.215-224
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• 2013

We clarified the background for establishment of vegetation by comparing the spatial distribution maps of vegetation and substrate on a gravel bar in the Bangtae stream located on Inje-gun of Gangwon-do, the central eastern Korea. The total vegetation coverage was higher in the interior and lower in the marginal parts of the gravel bar. Spatial distribution of vegetation on the longitudinal section of the gravel bar tended to be arranged in the order of shrub, subtree, and tree dominated vegetation types from the front (upstream) toward the rear (downstream) parts. Coverage of the herbaceous plants was higher in the central and rear parts and lower in the front and right parts of the gravel bar. Vegetation height was higher in the rear part and became lowered as move toward the front part. Substrate was distributed in the order of boulder, gravel, sand, and boulder from the front toward the rear parts. Ordination of stands based on vegetation data was arranged in the order of annual plant, perennial herb, shrub, and tree dominated vegetation as move from the right to the left parts on the axis I. Species richness was higher in the order of Pinus densiflora community, Phragmites japonica community, Salix gracilistyla community, Fraxinus rhynchophylla community, annual plant dominated vegetation, and Prunus padus for. padus community based on the species rank-abundance curve. The order based on the Shannon's index was some different; diversity of Phragmites japonica community and Salix gracilistyla community, which showed higher dominance degree, were low differently from species richness. In conclusion, it was evaluated that the gravel bar newly established toward the upstream and vegetation dynamics of the gravel bar seemed to follow ecosystem mechanisms of succession. As were shown in the above results, the Bangtae stream corresponded to the upstream and thereby particle size of substrate was big. Therefore, they move by rolling and are accumulated for the upstream. Vegetation types were arranged in the order of woodland, shrub-land and grassland from the rear toward the front parts of the gravel bar and thereby reflected the formation process of the bar. However, the gravel bar is disturbed frequently by not only the running water but also the suspended sand as the dynamic space. Such disturbances cause habitat diversity and consequently led to high biodiversity.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.157-168
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• 2001

Herbicides have been used to control weeds for decades. If detoxification upon exposure to herbicides requires considerable amounts of energy, it could affect the pattern of resource allocation to growth and reproduction of crops. We examined the effects of three levels of a herbicide (Control, Low, and High) on germination, growth and reproductive characters of Glycine max treated twice, i.e., before and after seed germination. Since flowering time of G. max was separated into two groups, flowering time was also considered as a variable in this study. The rate of seed germination tended to be higher at the low level of herbicide compared to other levels. Chlorosis and shape variation of leaves were apparent after the second herbicide treatment, but completely disappeared after six weeks of treatment. The herbicide effects on growth characters were somewhat different between early and late flowering plants, but plants treated with both low and high levels of herbicide reduced their growth compared to those in the control group regardless of flowering time. Plants at the high level of herbicide exhibited the highest growth rate later in the season, suggesting that plants compensated to some extent for reduced growth. However, growth reduction among plants at the high level of herbicide was persistent until the end of growing season. Among plants flowered late in the season, plants in the control level bore a higher number of nodules per plant than those in other levels; such a pattern did not exist among plants flowered early in the season. Plants treated with low and high levels of herbicide produced a lower number of flowers than those in the control. Thus, the herbicide examined affected not only the growth and reproductive characters of non-target crops but also the development and growth of root nodules.