Background: The abdominal drawing-in maneuver (ADIM), a method of lumbar stabilization training, is an effective neuromuscular intervention for lumbar instability associated with low back pain (LBP). Objects: The purpose of this study was to compare the effect of a 2-week period of the ADIM and tensor fasciae latae-iliotibial band (TFL-ITB) self-stretching on lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL-ITB length, and pain intensity during active prone hip lateral rotation. Methods: Twenty-two subjects with lumbar extension rotation syndrome accompanying shortened TFL-ITB (16 males and 6 females) were recruited for this study. The subjects were instructed how to perform ADIM training or ADIM training plus TFL-ITB self-stretching program at home for a 2-week period. A 3-dimensional ultrasonic motion analysis system was used to measure the lumbopelvic rotation angle and lumbopelvic rotation movement onset. An independent t-test was used to determine between-group differences for each outcome measure (lumbopelvic rotation angle, lumbopelvic rotation movement onset, TFL-ITB length, and pain intensity). Results: The results showed that ADIM training plus TFL-ITB self-stretching decreased the lumbopelvic rotation angle, delayed the lumbopelvic rotation movement onset, and elongated the TFL-ITB significantly more than did ADIM training alone. Pain intensity was lower in the ADIM training plus TFL-ITB self-stretching group than the ADIM training alone group; however, the difference was not significant. Conclusion: ADIM training plus TFL-ITB self-stretching performed for a 2-week period at home may be an effective treatment for modifying lumbopelvic motion and reducing LBP.

Background: The serratus anterior (SA) is a muscle that performs protraction of the scapulothoracic joint and plays a role in stabilizing the scapula. Imbalances or weaknesses in SA activation are associated with a variety of shoulder dysfunctions, making selective SA strengthening important for rehabilitation. Objects: We aimed to compare the muscle activation of the pectoralis major (PM), SA, external oblique (EO), and internal oblique (IO) during the push-up plus (PUP) exercise with isometric hip adduction (HA) and abdominal drawing-in maneuver (ADIM). Methods: Nineteen healthy male participants performed three PUP exercises: standard PUP, PUP with ADIM, and PUP with HA. Surface electromyography was used to measure and analyze the muscle activity for PM, SA, EO, and IO. Results: PUP with HA showed the lowest PM activity and highest SA activity, and no significant difference was observed between PUP and PUP with ADIM. PUP with ADIM showed significantly the highest EO and IO activity, followed by PUP with HA and PUP. Additionally, PUP with HA showed the lowest PM/SA ratio, and no significant difference was noted between PUP and PUP with ADIM. Conclusion: PUP with HA was able to show high SA muscle activity while reducing PM muscle activity. In addition, PUP with HA can lead to higher EO and IO muscle activity than standard PUP. This exercise could be used as a practical exercise method to selectively strengthen SA and improve scapular muscle stability during early shoulder rehabilitation.

현재뿐만 아니라 과거에도 병력의 기동은 전쟁 승리의 핵심이었다. 4 차 산업혁명시대 첨단 과학기술의 발달로 미래에도 기동전의 혁신적인 적용은 전쟁승리에 결정적 요인으로 작용할 것이다. 따라서 이번 연구 는 기동전의 4가지 특징을 중심으로 기동전을 자국의 여건에 맞게 진 화, 발전시켜 온 미국과 러시아의 전쟁 사례를 분석한 후 교훈을 도출하 여 미래 한반도에서 기동전 수행을 위한 발전방향을 제시하는 데 목적이 있다. 사례분석 결과 기동전의 4가지 특징에 맞게 기동전을 공지전투로 발전시켜 전투를 수행한 미국은 걸프전에서 승리하였다. 반면에 기동전 의 특징을 간과하고 변화된 환경에 적용하지 못한 러시아는 러-우전쟁 1단계 작전에서 실패하였음을 확인할 수 있었다. 또한 한반도에서 기동 전 수행을 위한 보완할 사항도 기동전의 특징을 중심으로 제시하였다. 본 연구는 기동전의 진화와 미·러의 전쟁수행 분석에 따른 교훈을 바탕 으로 미래 한국군의 기동전 수행방향을 제시했음에 의미가 있다. 본 연 구를 바탕으로 현장부대에서 구체적인 작전수행개념을 더욱 발전시켜 주기를 기대한다.

Background: To restore the trunk function of stroke patients who tend to experience trunk weakness, a single exercise intervention is usually applied. However, problems with the trunk remain even after such an intervention. To overcome this challenge, combining other intervention methods with an exercise is suggested during training. Objectives: To investigate the effect of breathing based abdominal draw-in technique on the thickness of the transversus abdominis muscle and trunk control in stroke patients. Design: Randomized controlled study. Methods: After designating a group that will perform the abdominal draw-in technique as Experimental Group I and another group that will perform the breathing based abdominal draw-in technique as Experimental Group II, the thickness of the transversus abdominis muscle and the trunk impairment scale (TIS) of the subjects were measured as pre-tests before the interventions and as post-tests after the six week intervention period. Results: In the within group comparison, there was a significant change in the thickness of the transversus abdominis muscle for both groups while the subjects performed the abdominal draw-in technique; a significant change was also noted in their TIS (P<.05) (P<.01). However, in the inter-group comparison, a significant difference was found only in the TIS between the two groups (P<.05). Conclusion: After the application of the breathing based abdominal draw-in technique, an efficient contractile response was observed even in the muscles around the abdomen of the subjects, which indicates that this technique is an intervention method that can more effectively improve trunk control.

페르시아 전쟁(기원전 490-479년)을 시작으로 알렉산드로스 대왕의 죽음(기원전 323년) 에 이르기까지 크고 작은 전투와 전쟁이 끊임없이 벌어졌던 그리스의 전장에 세워진 트로파이온에는 고전기 그리스인들의 전쟁과 승리에 대한 관념이 담겨있다. 그리스의 초기 트로파이온은 전장에 전쟁의 승패가 결정된 직후에 세워진다는 특징을 갖는다. 그리고 그것을 세움으로써 승자는 신들에 대한 감사를 표현하고 미래의 전투에 대한 승리를 담보하고자 하였다. 동시에 이것은 전우들과 승리의 기억을 공유하고, 적군에게는 패배를 시각적으로 각인시킴으로써 그들의 잠재적인 도발의 의지를 상실하게 만드는 마지막 전략이기도 하였다. 본 연구에서 살펴본 기원전 5세기의 도기들과 아테나 니케 신전의 난간을 장식한 부조는 그러한 전술의 기록이다.

The purpose of this study was to assess knee joint loading in the target knee during a golf swing compared to loading rates of high impact activities such as cutting and drop landings. Nine healthy competitive golfers completed golf swings with the target foot both straight and externally rotated 30 degrees, as well as drop landings and cutting maneuvers. Motion capture data was collected at 240 Hz and ground reaction force data was collected at 2400 Hz. The frontal and transverse knee moments were examined using repeated measures ANOVA through SPSS. The abduction moments were higher in golf swings as compared to the other high impact activities (p=.010), while the external rotation moments were lower (p=.003). There were no significant differences between externally rotated and neutral golf swings. These results suggest moments applied to the knee during a golf swing are similar to those applied during a high impact activity.

목적 : 본 연구는 저항운동으로 6주간 적용된 혀-유지 메뉴버 프로그램이 Shaker 운동 프로그램과 비교하여 정상성인의 삼킴 근육 활성도에 미치는 영향을 알아보고자 하였다. 연구방법 : 2015년 10월부터 12월까지 10대에서 50대의 건강한 성인 26명을 대상으로 혀-유지 메뉴버 그룹과 Shaker 운동 그룹으로 무작위 할당하여 주 5일, 하루 1회, 30분씩 6주간 적용하였다. 표면근전도를 사용하여 설골상근 (suprahyoid muscle)과 설골하근(infrahyoid muscle)에 대한 근활성도를 수집하였다. 시각적 비율척도(Visual Analog Scale), 자각인지 척도(Borg-Rating of Perceived Exertion Scale) 척도를 사용하여 삼킴 시 노력과 피로를 측정하였다. 결과 : 혀-유지 메뉴버 그룹과 Shaker 그룹 모두 설골상근과 설골하근의 근활성도가 유의한 향상을 보였지만, 두 그룹 간의 유의한 차이는 없었다. 또한 두 그룹 모두 삼킴 시 노력 및 피로가 통계학적으로 유의한 차이를 보였으나, 두 그룹 간의 유의한 차이는 없었다. 결론 : 건강한 성인을 대상으로 6주간 혀-유지 메뉴버를 통해 삼킴 근육 근활성도에 대한 긍정적인 효과를 확인하였다. 향후에는 삼킴장애 환자를 대상으로 혀-유지 메뉴버에 대한 임상적 효용성을 검증하여 유용한 치료기법으로 사용되기를 기대한다.

Background: Improvement of lumbo-pelvic stability can reduce the compensatory action of the quadratus lumborum (QL) and selectively strengthen the gluteus medius (GM) during side-lying hip abduction (SHA). There are abdominal draw-in maneuver (ADIM) and abdominal bracing (AB) as active ways, and pelvic compression belt (PCB) as a passive way to increase of lumbo-pelvic stability. It is necessary to compare how these stabilization methods affect the selective strengthening of the GM. Objects: To investigate the effects of ADIM, AB, and PCB during SHA on the electromyography (EMG) activity of the GM, QL, external oblique (EO) and internal oblique (IO), and the GM/QL EMG activity ratio. Methods: A total of 20 healthy male adults participated in the study. The subjects performed three conditions in side-lying in random order: SHA with ADIM (SHA-ADIM), SHA with AB (SHA-AB), and SHA with PCB (SHA-PCB). To compare the differences among the three conditions, the EMG activities of the GM, QL, EO and IO, and GM/QL EMG activity ratio were analyzed using one-way repeated ANOVA. Results: The EMG activity of the QL was significantly higher in SHA-AB than in SHA-ADIM and SHA-PCB. The GM/QL activity ratio was significantly higher in SHA-PCB than in SHA-ADIM and SHA-AB. In addition, the figure for SHA-ADIM was significantly higher than that for SHA-AB. In the case of the EO, the figure for SHA-AB was significantly higher than corresponding values for the other two conditions. The figure for SHA-ADIM was significantly higher than that for SHA-PCB. The EMG activity of the IO was significantly higher in SHA-AH than in SHA-PCB. Conclusion: It can be suggested that wearing the PCB can more selectively strengthen the GM than to perform ADIM and AB during SHA. In addition, the ADIM can be recommended when there is a need to strengthen abdominal muscles during SHA.

적외선 유도 미사일은 미사일에서 자체적으로 방사하는 신호가 없어 항공기에서 접근을 인지하고 대응하기가 어렵다. 또 한 적외선 유도 미사일을 탐지하는 MAW(missile approach warning)는 고가의 장비로 현재는 항공기에의 사용이 제한되고 있으며 그 효용성이 공개된바가 없다. 따라서 본 연구에서는 MAW가 탑재되어 항공기가 접근하는 유도 미사일에 대해 회피 기동을 수행할 때 항공기의 생존성이 얼마나 증가하는지를 해석하여 MAW의 효용성을 평가하고자 하였다. 생존성의 평가 지표로 위험 거리를 사용하였으며 고도 5km를 마하 0.9로 비행하는 항공기에 대해 AIM-9 적외선 유도 미사일이 접근하는 상황에 대한 위험 거리를 방위각 별로 도출하였다. 항공기의 회피기동에 대한 변수로는 5～7km의 MAW 인지거리와 3～7G 의 항공기 기동성능을 고려하였다. 해석 결과 MAW를 통한 미사일 접근 인지와 회피기동 만으로도 위험 거리가 상당히 감소하는 것을 확인했다. 회피기동에 따른 위험 거리의 감소는 최대 29.4%로 나타났다. 또한 상대적으로 향상시키기 어려운 항공기 기동성능보다는 MAW 인지거리를 증가시키는 것이 위험 거리의 감소에 더 효과적인 것으로 나타났다.

Background: Scapular winging is a prominence of the entire scapular medial border, mainly caused by insufficient activity of the serratus anterior (SA) and imbalance of scapulothoracic muscles. Push-up plus (PUP) exercise has been commonly used to increase SA muscle activity. The facilitation of abdominal muscle may affect scapular muscle activity by myofascial connections. Thus, the sequential activation of the turnk muscles is suggested to facilitate the transition of proper force from upper limb and restore force couple of scapular muscles. The abdominal drawing-in maneuver (ADIM) has been effective in improving activation of the deep trunk muscles during movement. Objects: The aim of this study was to determine the effect of ADIM on the activity of the upper trapezius (UT), lower trapezius (LT), and SA during PUP exercises in subjects with scapular winging. Methods: Fourteen men with scapular winging (determined as a of distance between the scapular medial border and thoracic wall over 3 ㎝) volunteered for our study. The subjects performed the PUP exercise with and without ADIM. Surface electromyography was used to collect the electromyography data of the UT, LT, and SA. A scapulometer was used to measure the amount of scapular winging. Results: SA activity was significantly greater and scapular winging significantly lower during the PUP exercise with ADIM than during those without ADIM. Conclusion: PUP exercise with ADIM can be used as an beneficial method to improve SA activation and to reduce the amount of scapular winging in subjects with scapular winging.

목적:본 연구는 저항 운동으로 8주간 적용된 혀-유지 메뉴버 프로그램이 삼킴 근육의 활성도에 미치는 영향을 측정하고자 하였다. 연구방법:2012년 1월부터 3월까지 건강한 성인 27명을 대상으로 실험군과 대조군으로 나누어 혀-유지 메뉴버를 8주간 적용하였다. 실험군은 혀-유지 메뉴버를 하루 3회, 20분씩 수행하였으며 대조군은 혀-유지 메뉴버가 아닌 일반 삼킴을 하루 3회, 20분씩 적용하였다. 8주간의 실험 효과는 삼킴에 주로 관여하는 설골상근(suprahyoid muscle)과 설골하근(infrahyoid muscle)에 대한 표면근전도 및 시각적 비율 척도(Visual Analog Scale; VAS)를 통하여 측정되었다.결과:각 그룹별 훈련 전·후 비교 결과 실험군은 설골상근(suprahyoid muscle)과 설골하근(infrahyoid muscle) 모두에서 근 활성도가 통계학적으로 유의하게 나타났으나 대조군은 통계학적으로 유의하지 않은 변화를 보였다. VAS 값의 훈련 전·후 비교에서도 실험군은 유의한 차이를 보였으나 대조군은 통계학적으로 유의하지 않았다. 결론:건강한 성인을 대상으로 8주간의 저항 운동으로서 혀-유지 메뉴버를 적용하였을 때, 삼킴근육의 근활성도의 변화와 VAS 값의 변화를 일으킨다는 것을 알 수 있었다. 향후 연구에서는 삼킴장애를 가진 환자들을 대상으로 직접적인 관리 하에 8주간의 혀-유지 메뉴버 저항 운동 프로그램 적용의 효과를 검증한다면, 혀-유지 메뉴버를 교정적 접근법으로 적용할 수 있다는 명확한 이론적 근거가 될 것이다.

This study was conducted in order to examine whether abdominal draw-in maneuver (ADIM) with isometric shoulder flexion, extension, adduction, and abduction selectively contracted deep abdominal muscles. This study's subjects were 13 males 17 females. In order to evaluate the comparison of effects of ADIM and ADIM with isometric shoulder flexion, extension, adduction and abduction, measurements were made on transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) using a real-time ultrasonic diagnostic imaging system. Each position was repetitively measured three times with a real-time ultrasonic diagnostic imaging system and their mean values were used for analysis. The ADIM with isometric shoulder flexion, extension, adduction and abduction significantly increased the thickness of TrA relative to the ADIM only (p<.05). The ADIM with isometric shoulder abduction significantly increased the thickness of IO compared to the ADIM only (p<.05). The ADIM with isometric shoulder extension and abduction significantly decreased the thickness of EO compared to the ADIM only and the ADIM with isometric shoulder extension significantly decreased the thickness of EO relative to the ADIM with isometric shoulder adduction (p<.05). ADIM with isometric shoulder abduction is an effective method to selectively strengthen deep abdominal muscles and therefore may be employed as an intervention for trunk stabilization.

The aim of this study is to compare the effect of abdominal drawing-in maneuver (ADIM) on lower trapezius (LT), serratus anterior (SA), and erector spinae (ES) muscle activity during arm lifts in prone and standing positions. Twenty healthy subjects were recruited, and NoraxonTeleMyo 2400T was used to collect electromyographic signals from the LT, SA, and ES muscles. A two-way repeated analysis of variance (ANOVA) used a significance level of .05. If a significant interaction was found, pairwise comparisons were performed with a Bonferroni adjustment (.05/4=.013). The results of the study were as follows: 1) In LT, no significant ADIM by position interaction was found (=.356, p=.558). There was a significant main effect for ADIM. LT muscle activity with ADIM was significantly greater compared with muscle activity without ADIM (=82.863, p<.001). There was also a significant main effect for position. LT muscle activity in the prone position was greater compared with muscle activity in the standing position (=116.401, p<.001). 2) In SA, significant ADIM by position interaction was found (=8.687, p=.008). There were significant differences in all pairwise comparisons. The greatest SA muscle activity was observed in the standing position with ADIM. 3) In ES, significant ADIM by position interaction was found (=122.473, p<.001). The lowest ES muscle activity was elicited in the standing position with ADIM. Based on these results, ADIM is advocated in the prone position to increase LT muscle activity. In addition, it is concluded that arm lifts in the standing position with ADIM offer the most favorable combination for reducing ES muscle activity and increasing SA muscle activity.

This present study investigated the effects of the abdominal drawing-in maneuver (ADIM) and chin tuck (CT) on middle thoracic erector spinae, lower thoracic erector spinae, and lumbar erector spinae muscle activity during three prone thoracic extension (PTE) exercises. Twelve healthy subjects performed preferred PTE, ADIM PTE, and ADIM-CT PTE. Surface electromyography was used to collect data on the muscle activity of dominant middle and lower thoracic erector spinae muscles and the lumbar erector spinae. Middle and lower thoracic erector spinae muscle activity significantly increased when ADIM and CT was performed (p<.05). However, lumbar erector spinae muscle activity significantly decreased in ADIM PTE compared to preferred PTE (p=.017) and significantly increased in ADIM-CT PTE compared to ADIM PTE (p=.004). In conclusion, ADIM-CT PTE effectively increased middle and lower thoracic erector spinae muscle activity, and ADIM PTE decreased lumbar erector spinae muscle activity. Hence, ADIM PTE could be a recommended exercise maneuver to strengthen thoracic erector spinae without over activation of lumbar erector spinae.

The aim of this study was to investigate the effects of respiratory muscle training (RMT) with abdominal drawing-in maneuver (ADIM) on pulmonary function. Twenty-two subjects with restrictive breathing participated in this study. All the subjects were randomly assigned to three groups (7 subjects in RMT group, 7 subjects in RMT with ADIM group, 8 subjects in control group). The first group performed the RMT by using incentive respiratory spirometer (IRS). The second group performed the RMT by using IRS and the ADIM by using a Stabilizer. The exercises were conducted over four days. The pulmonary function was evaluated using the spirometer to measure the force exploratory volume in 1 second () and forced vital capacity (FVC). Measurements were conducted on the first day and the last day. A paired-t test was used for pre-post changes and the change rates in FVC and among each group were investigated by a one-way ANOVA. The findings of the the study were as follows: 1) There were significant differences of FVC and between pre and post in the two training groups (p<.05) 2) There was no significant difference of the change ratio the FVC and between the RMT group and RMT with ADIM group. Therefore, it is concluded that respiratory muscle and ADIM training, combined with two methods of treatment would suggest positive evidence for improving pulmonary function.

The aim of this study was to investigate the effect of abdominal drawing-in maneuver (ADIM) on peak exploratory flow (PEF), forced exploratory volume in 1 second (FEV1), and low back pain during forced expiration. Twenty-two subjects (14 subjects in experimental group, 8 subjects in control group) participated in this study. The stabilizer was used for ADIM training for five consecutive days. Vitalograph PEF/FEV1 DIARY and visual analogue scale (VAS) were used to determine forced expiratory pulmonary function and low back pain, respectively. Independent t-test and analysis of covariance were used for statistical analysis with a significance level of .05. The findings of this study were as follows: 1) There were no significant differences of ADIM effect on PEF and FEV1 between experimental group and control group. 2) There was a significant pain reduction in experimental group with ADIM. 3) PEF and FEV1 increased significantly in the fifth day compared with the first day pre-exercise baseline. Therefore, it is concluded that ADIM was effective in improving PEF and FEV1, and reducing VAS during forced expiration in patients with chronic low back pain.

An abdominal drawing-in maneuver (ADIM) with a pressure biofeedback unit can be used to prevent excessive lumbar lordosis during bridging exercise. Therefore, in this research, the effects of an ADIM on lumbar lordosis and lower extremity muscle activity during bridging exercise were investigated in thirty healthy adults. Surface electromyography (EMG) and VICON system were used to collect kinematic data and muscle activity, respectively. A paired t-test was used to determine a statistical significance. The results showed as follows: (1) When performing bridging exercise with an ADIM, the height of the anterior superior iliac spine and greater trochanter decreased significantly (p<.05). (2) When performing bridging exercise with an ADIM, the trunk extension angle and pelvic angle increased significantly (p<.05). (3) When performing bridging exercise with an ADIM, the EMG signal amplitude increased significantly in the rectus abdominis, internal oblique abdominis, external oblique abdominis, medial hamstring, and lateral hamstring (p<.05). (4) When performing bridging exercise with an ADIM, the EMG signal amplitude decreased significantly in the erector spinae (p<.05). From the result of this research, an ADIM trained with pressure biofeedback unit during bridging exercise is effective to prevent excessive contraction of erector spinae, to limit excessive motion of pelvis from sagittal plane and to increase muscle activity of abdominal muscles and hamstring muscle.

This study examined the effects of the abdominal drawing-in (ADI) maneuver using a pressure biofeedback on muscle recruitment pattern of erector spinae and hip extensors and anterior pelvic tilt during hip extension in the prone position. Fourteen able-bodied volunteers, who had no medical history of lower extremity or lumbar spine disease, were recruited for this study. The muscle onset time of erector spinae, gluteus maximus, and medial hamstring and angle of anterior pelvic tilt during hip extension in prone position were measured in two conditions: ADI maneuver condition and non-ADI maneuver condition. Muscle onset time was measured using a surface electromyography (EMG). Kinematic data for angle of anterior pelvic tilt were measured using a motion analysis system. The muscle onset time and angle of anterior pelvic tilt were compared using a paired t-test. The study showed that in ADI maneuver during hip extension in prone position, the muscle onset time for the erector spinae was delayed significantly by a mean of 43.20 ms (SD 43.12), and the onset time for the gluteus maximus preceded significantly by a mean of -4.83 ms (SD 14.10) compared to non-ADI maneuver condition (p<.05). The angle of anterior pelvic tilt was significantly lower in the ADI maneuver condition by a mean of 7.03 degrees (SD 2.59) compared to non-ADI maneuver condition (15.01 degrees) (p<.05). The findings of this study indicated that prone hip extension with the ADI maneuver was an effective method to recruit the gluteus maximus earlier than erector spinae and to decrease anterior pelvic tilting.

The Steering and Sailing Rules of International Regulation for Preventing Collisions at Sea now in use direct actions to avoid collision when two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision. But these rules do not refer to the minimum relative distances and safety relative distances between two vessels when they should take such actions.In this paper the ship's collision avoiding actions being analyzed from a viewpoint of ship motions, the mathematical formulas to calculate such relative distances necessary for taking actions to avoid collision were worked out. The values of maneuvering indices being figured out through experiments of 20 actual ships of small, medium, large and mammoth size and applied to calculating formulas, the minimum relative distances and safety relative distances were calculated. The main results were as follows. 1. It was confirmed that the criterion elements for collision avoiding actions in head-on situation of two vessels shall be the minimum relative distances and safety relative distances between them. 2. On the assumption that two vessels same in size and condition were approaching each other in head-on situation, the minimum relative distance of small vessel(GT : 160~650tons) was found to be about 4.7 times her own length, and those of medium (GT:2,300~4,500tons),large(GT:15,000~62,000tons) and mommoth (GT:91,000~194,000tons) vessels were found to be about 5.2 times, about 5.2 times and about 6.1 times their own lengths respectively. 3. On the assumption that two vessels same in size and condition were approaching each other in head-on situation, the safe relative distance of small vessel (GT : 160~650tons) was found to be about 6.8 times her own length, and those of medium (GT : 2,300~4,500tons), large (GT: 15,000~62,000tons) and mammoth (GT : 91,000~194,000tons) vessels were found to be about 9.0 times, about 6.3 times, and about 8.0 times their own lengths respectively. 4. It is considered to be helpful for the safety of ship handling that the sufficient safe relative distances for every vessels shall be more than about 12~14 times which are 2 times minimum relative distance, their own length on above assumption.